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TWiP 89 letters

Robin writes:

Cerebral cysticercosis


Left shift:
This is from the days when dinosaurs roamed the earth:
Manual counters for the differential count had the buttons left to right for neutrophils, bands, eosinophils, basophils, lymphocytes, and monocytes. More of the one hundred button presses on the left buttons constituted a left shift.

differential counterFive key differential counter



When this one is needed, the patient has a problem.

Christine writes:

The case described sound like neurocysticercosis caused by brain infiltration of larvae of the pork tapeworm Taenia solium and the immune systems response to it. Although she claims to not currently eat meat other than chicken (for economic reasons) this does not exclude consumption at celebrations or on rare occasions in the more distant past.

This diagnosis is supported by the lack of eosinophilia and the neutrophilia without left shift is most likely due to demargination.

As a side note Dickson's explanation of left shift is right on the money as I was taught.

The weather here in Brisbane is changeable after a devastating east coast low that brought flooding, intense rains on Friday, to a delightful, sunny autumn day with 26 C temps for Saturday, we have clouded over with light showers again today (Sunday) but still a delightful 26 degrees and a light breeze.

Christine from Brisbane.

Jan writes:


Is it Cystiscerosis ? That would fit the complaints, it's common in that part of the world and the fact that you can acquire this parasite from fecal contamination of foodstuffs by infected animals without eating meat makes me lean that way.




the weather is 15 c, occasional drizzle and the cherries are blooming.

Wink writes:

With the information provided, you must expect neurocysticercosis. If it's a zebra, my wild and crazy guess would be an errant Echinococcus vogeli.

Bjorn writes:

I’m making a wild guess on this one. Wild in the sense that it’s atypical, but not entirely
impossible: I’m guessing tht this was a case of latent malaria breaking out, possibly
in the form of cerebral malaria. The reasoning is this:

o The patient is from central america, where she lived for many years.
She might very well have picked up Malaria there. The shaking chills she presents
is a typical symptom that may well be caused by malaria.

o The seizure she had is consistent with cerebral malaria, so this is consistent.

o If the form of Malaria she picked up was Plasmodium Vivax or p. Ovale or p. Malariae,
since these particular species have an abiity to hibernate in the liver for many
years or even decades in the form of clinically “invisible” hypnozoites.

o She might not even have had any malaria apparent infection previously, so this could
be the first time she experiences malaria symptoms. It is also possible that she
has had malaria previously, but has ignored it. The family only took her to the
ER after she had multiple seizures, so a little bit of shaking chills might not have been
enough to make medical attention seem necessary.

To confirm or reject this diagnosis use a quick diagnostic test for all the known malaria forms,
and if any of them are positive start medication immediately. Blood smearr (thick + thin) would
also be nice to confirm/reject malaria and also identify the species.

The internet tells me that he weather is nice outside, but since I’m in a train, in a tunnel on my way to work
I really couldn’t tell.

Elise writes:

Dear TWIP Trifecta,

I hope this finds you all well and frolicking in this gorgeous moment of New York springtime. It’ll only be here for a few moments before summer swamps in, so frolic while you can.

I think I have a diagnosis for the patient featured in TWIP 88. I suspect strongly that the patient has Neurocysticercosis, caused by tapeworm larvae (taenia solium). (There are two types of neurocysticercosis — the parenchymal and extraparenchymal — and I don’t know if both can cause the seizures the patient has so I can’t be more specific, diagnostically.) I know the patient was emphatic about how she doesn’t eat any meat, but it is much more likely to become infected with tapeworm larvae through fecal-oral contamination than from eating undercooked meat (which would lead to intestinal tapeworms, anyway). Fecal-oral contamination also makes it possible for the larvae to make their way to the brain, eventually creating cysts that can lead to seizures of the sort that brought the patient to the emergency room.

There are a lot of possibilities as to how the patient got infected. She came to the United States from El Salvador ten years ago. Cysticercosis and neurocysticercosis are both quite common infections in developing countries, and the incubation period can be extremely long. In addition, she could have contracted the parasite from someone who visited who was infected. In general, most cases of cysticercosis and neurocysticercosis in the United States do occur in immigrants from Latin American countries, but they can also show up in people who travel to countries where tapeworm infections are common or patients who have contact with carriers. Cases in the United States are on the rise. The CDC was very clear about how widespread this sort of infection is and has put it on its list of “Neglected Parasitic Infections” (which is a great name) that need public health attention.

I was interested to read that neurocysticercosis is a leading cause of adult onset epilepsy in developing countries. I didn’t realize that the diagnosis of “epilepsy” could refer to this sort of seizure disorder.

What would be the best thing to do for this patient? Her seizures are not the sort that would necessarily regulate with epilepsy medications. Most of the sources I found noted that antiparasitic medications would cause more brain swelling and pressure. (And also, unless I misunderstand, it seems as if the seizure activity occurs as the larvae are dying, so does it stop once the larvae are dead? Will this eventually resolve?)

As always, thank you so much for your work and for your wonderful podcasts. I truly look forward to them.


AJ writes:

Hello parasailing parasitologists!

Another interesting case! I’m shooting from the hip here, but sounds like neurocysticercosis. Not eating pork keeps her from acquiring the adults, in her intestines, like the worm wants. But if one of her meat eating friends had adult worms, got eggs on their fingers, and then made everyone a salad… well then she could very well have dead or dying larvae in her brain. Then no one wins! Taenia solium is still very common in many South American countries, and while it seems unusual that she could be experiencing symptoms from a ten year old exposure, the adults could easily live that long in a friend or family member’s intestines. Or, maybe a friend visited San Salvador and picked up some worms more recently.

Looking forward to hearing the answer!

PS. The weather in San Diego: still dry.

Grace writes:

Dear Twippees,

This is another joint effort by me, Grace, and my science girlfriend, Caylee. We think the culprit in the case of the seizure-ing woman from El Salvador is Taenia solium, the pork tapeworm.

This lovely parasite may have taken up residence in the patient years ago through contaminated pork before she ever moved to the U.S. and found purchasing meat too costly.

We write to you from mile-marker-18, Idaho, the closest place to our field residence that gets cell service. The small mammals of Idaho send their greetings.

Best wishes,
Grace and Caylee

Carol writes:

Greeting, TWIPpers,

I missed writing in last episode, but I was pleased to hear that what I had guessed was correct. This time I'm managing to write before the next episode is up.

My guess for the case study this episode is neurocysticercosis; just because she reports not eating meat due to the expense now doesn't mean she didn't eat it during the 23 years before she immigrated. I don't eat meat now, partly for ethical and partly for economic reasons (finding meat that has been raised in a manner I can accept is possible, but it's out of my price range), but my entire extended family does and I did while growing up.

The weather here in Victoria is, again, sunny and mild, with a nice ocean breeze. Vincent will be happy to hear that there are no longer any cherry blossoms messying up the trees, though he might be disappointed that the lilacs are in full bloom.

Looking forward to the next TWIx podcasts eagerly, as they provide a nice break from studying for summer courses without making me feel guilty for not learning things,


Dona writes:

Heard your recent podcasts and am writing re the case study this week. First though, feel obliged to update you on the weather in Oxford, UK today - warmish (up to 18 degrees) and cloudy but no rain.

Is the case study cysticercosis caused by Taenia solium? If it is, would you treat the family, especially the infant?

Found this paper from 10 years ago, suggesting cases were going up in US - is this true today?


Varun writes:

Greetings Professors,

In response to TWiP# 88 case..

There is a series of parasite to be considered when it comes to parasites related to seizures. Ref:
From the given list of symptoms is probably pointing towards Neurocysticercosis. Though classically it is a meat derived condition, there are sufficient conditions described by transmission through unwashed vegetables, with fecal contamination. Am also considering that it also can sometimes have a unusually long incubation periods.

I would like to know if there was any significant findings from brain imaging, what was the differential count, an IgG ELISA for cysticercosis and Toxoplasma.

My guess- NCC (Neurocysticercosis), casued by cystic larvae of Taenia solium

Anne writes:

Dear TWIP team,

My thoughts for the woman from El Salvador are that the case description best fits that of cerebral cysticercosis (neurocysticercosis.) It is acquired through ingestion of tape worm eggs in the feces of an infected human carrying the intestinal tapeworm Taenia solium. This represents an aberrant form of the life cycle. Typically, the lifecycle would be completed by a pig ingesting material contaminated with human feces containing the eggs and humans would then in turn acquire the tapeworms through ingestion of undercooked pork containing the larval stage. It is an important cause of acquired epilepsy in areas where Taenia solium infection is common and sanitation is poor.

Turns out it occurs in my home state too :
O'Neal S, Noh J, Wilkins P, Keene W, Lambert W, Anderson J, Compton Luman J,Townes J. Taenia solium Tapeworm Infection, Oregon, 2006-2009. Emerg Infect Dis. 2011 Jun;17(6):1030-6. PubMed PMID: 21749764;PubMed Central PMCID: PMC3320238.

I am mildly disappointed with Dickson’s dismissive comments this week about current veterinary education. Certainly the scope of knowledge required to become a board certified veterinary pathologist is extensive. I will point out that we don’t have the luxury of studying only one species.

I adore the show and look forward to the podcasts as they come out. Thanks as always.

Beaverton, OR

Adam writes:

Hello my good sirs,

In response to TWIP 88's case, unless the little 10-year bit is a total red herring, I believe this may be Chagas disease, or Trypanosoma cruzi!

A quick story about why this comes to mind: A few years ago, I was in rural Nicaragua working on a water sanitation project. We had a Peace Corps volunteer accompany us who woke everyone up in the middle of the night because she found one of the "kissing bugs" that we learned were vectors of T cruzi. She explained that if we were to see one in the stable where we were staying (yes, we were sleeping in a converted stable), to trap it and find her so she could capture it and give it to the government health organization, presumably for epidemiological purposes. This raised lots of questions and she had to explain that these bugs can give people a parasite that can cause sudden death 10 or 20 years after being bitten. Needless to say, this freaked a whole bunch of people out and kept them up all night. I, for one, thought it was fascinating and it made me seek out more information about parasites when I got back home!

On this same trip, I went swimming barefoot in a lake with some locals (spectacular idea, I know...). I thought this was really great and all until I came out of the water and noticed that grass leading into the lake was littered with cow pies! Within 24 hours, I had some nasty diarrhea that passed within a day. Luckily I had some Lomotil to keep me "stopped up" for the bus ride home. Wish I could figure out the pathogen that made me sick!

Anyway, sorry for the lengthy reply and story. Thanks for all you do to promote scientific literacy! I am a middle school science teacher in Chicago who is applying to medical school this year. The podcast trifecta give me lots of great lesson ideas for my kids, and keep me intellectually stimulated after long, monotonous days. Keep up the incredible work.


PS - Is it weird that I hope I picked up some parasite in Central America? I went to school in Eugene, Oregon, which happens to be just about the grass pollen capital of the world around this time of year, and developed some severe allergies while there. It would be cool to see if they persist after my trip - my own little "hygiene hypothesis" experiment!

I emailed a heme/onc doc I have been shadowing who guesses that "she has neurocysticercosis - a form of T. solium, the pig tapeworm. The fact that she doesn't eat meat doesn't mean anything, It can be transmitted fecal-oral, so if no hand washing she can get it."

After researching this a little bit more and learning that T. solium is the leading cause of adult onset epilepsy worldwide, it seems like neurocysticercosis is a much better guess than Chagas disease!


Someone wrote:
This is a review but is gamma interferon the intrinsic factor described by Dixon versus leishmania?

AJ writes:

Hello fellow parisamaniacs,

This week's case study seems to me to be a case of Leishmaniasis. The ulcer sounds much like leishmaniasis, especially as it is painless, and the subject knows he's been bitten by some sort of dipteran or another. Italy isn't an unreasonable place to pick the disease up, although it isn't terribly common.

I'm not sure if the hep C would tie into that. Also, Dick kept asking about fish and beaches, which made me consider vibrio and mycobacteria briefly, but those are outside the scope of twip. I'm not sure if phlebotamous would bread near beaches specifically, and they only feed at night, so I'm not sure it's relevant.

Keep up the great work! I love the clinical cases, although this is the first time I've had any clue as to what the diagnosis might be.
Thanks always,

Grace writes:

Dear TWIP Team,

This attempt at cracking the case study is a joint effort. It comes to you from a duo of small mammal biologists searching for enzootic plague out in west central Idaho. With no good radio stations, downloading episodes of TWIP and TWIV for our long commute to the field each day helps keep us sane.

Apologies if the format of this letter is wrong, and if our answer is totally off the mark. We researched what we thought were the pertinent clues in a sunny cafe in Boise, and our most educated guess is Cutaneous Leishmaniasis caused by Leishmania infantum. The patient could have been bitten by a sandfly during one of his trips to southern Italy. Sandflies are at their lowest levels during the time of his trip (winter), but the incubation for L. infantum can be long, lasting up to years.

Thanks for the great podcast! It's lots of fun for those of us in the uncertain purgatory that is the time between undergrad and grad school to have a reason to use our brains again.

Best wishes,

Buboes from Idaho

George writes:

Hi Vinny. Nice discussion brought to my attention by Monica. Of course, I had to explain the story to everyone in the lab

TWiP 88 letters


Robin writes:

Cutaneous leishmaniasis.
CL has been endemic in Italy at a relatively constant level since the 1970s, in the same areas that are endemic for VL. CL is largely underreported to the MoH. Only cases that are diagnosed and treated in hospitals are reported, but those diagnosed in private clinics are not. It was estimated that 450–500 cases occurred both in 2004 and 2005.

Christine writes:

Dear Doctors Vincent,Dickson and Daniel,

Having listened to your latest podcast I am less disappointed that I was stumped over twip 86. I had excluded most things I could think of due to a lack of fever or diarrhea.

This week however sounds like a case of cutaneous Leishmaniasis. This would have been transmitted by the bite of a sandfly. Would be worth sampling the edge of the lesion to id.

The weather here in brisbane has been beautiful blue skies, fresh westerly winds and a high of 25C.


Wink writes:

If this is leishmaniasis, my question for Dixon is where do sand flies live -- beach, desert, grass?

Bjorn writes:


My guess would be is cutaneous leishmaniasis. It’s not that common in Italy, but it’s certainly not unheard of.

He could have been bitten by a sandfly vector while on the beach. A definitive diagnosis can be made by demonstration of the organism in the tissue surrounding the lesion. If the organism spreads beyond the skin, it can establish a visceral leishmaniasis. Here are some signs one can look for to confirm a diagnosis for that condition:

* There may be hypergammaglobulinemia and hypoalbuminemia
• Liver enzymes commonly elevated
• Pancytopenia very common
• Diagnosis by demonstration of the organism
• Commonly done through splenic puncture, liver or bone marrow biopsy, lymph node aspiration, or staining of peripheral blood buffy coat.

Assuming that this is cutaneous leishmaniasis, the treatment may be just to let the thing heal itself. However, do observe for signs of visceral leishmaniasis since that will require treatment. Most commonly utilized medication is pentavalent antimonial compound
stibogluconate. Alternative options can include liposomal amphotericin B, pentamidine, azoles and miltefosine.

All of this is fresh off my notes from the wonderful Coursera course in “Tropical Parasitology: Protozoa, Worms, Vectors and Human Diseases". As a software engineer I don’t know much about parasites, but what little I do know comes from "this week in parasitism" and that single coursera course. Parasites are fascinating :-)

Keep it up doctors, you are an inspiration.

Elise writes:

Dear TWIP Gang,

How are you? Many thanks again for your case studies. I love working on these and was not event remotely mortified by not getting the answer to TWIP 86 correct. I never would have guessed pinworms would be the culprit. (And that is a sentence I am glad I have never had an opportunity to compose prior to today.)

For TWIP 87, I have done some research and it looks very much like cutaneous leishmaniasis. All of the symptoms the patient exhibits pretty much line up. The lesion he presents is consistent with cutaneous leishmaniasis: large, painless, unhealing sore (beginning as a small painless bump), with a fibrous scabby covering, with the infection limited to the lesion, and not spreading beyond.

The patient was in Southern Italy and spent time on the beach, where he very well may have offered up an appealing meal for the sand flies that spread the infection through bites. The CDC and other sites report that cutaneous leishmaniasis is widespread (present in large parts of: Asia, the Middle East, Africa, southern Europe, Mexico, Central America, and South America), and the incubation period is about right. I suspect the patient’s elevated blood pressure is unrelated to the lesion.

(I should also add that the glee with which all of you introduced the description of the symptoms and the patient profile made me think that this would probably be a less subtle problem than the one in TWIP 86, which is why I am offering a not-uncommon diagnosis.)

Finally, I read in a number of places that these lesions cause permanent scarring. Would it be possible to minimize the scarring if the diagnosis is made sooner or is the damage inevitable?

Thank you so much again. It is 68 degrees F (20 degrees C) in lower Manhattan and the skies are blue, and it is hard to believe that it is going to pour in a couple of hours.

Cheers and best to all of you

Scott writes:


As a longtime listener, I have enjoyed your case presentations, and though I have no competence as a diagnostician, have enjoyed speculating about possible diagnoses.

The case presented in the current TWIP struck a chord with me. Living here in Costa Rica, where myiasis caused by Dermatobia hominis is fairly common (there are some really gruesome photos to be found on the web), the presentation sounded actually quite familiar. I can't speculate as to the species involved, as I am not that familiar with the species of parasitic flies that are found where the patient had been traveling, but myiasis would be my guess at a diagnosis.

Somewhere I heard a story about a biologist who was infested here, and decided to let nature take its course once he got back home, so he could document the development of the larvae to its emergent stage. As I recall, it got just too painful to tolerate and he had to remove it prior to the emergence, but even so, doing such a thing strikes me as being truly heroic dedication to science. I was infested with one once, and removed it as soon as I discovered it - I can testify that it was painful even when still quite small.

Cartago, Costa Rica


TWiP 87 letters


Jan writes:

Hello doctors,

This was indeed not easy to Google; one of my attempts even had a dr oz page as one of search results. Clearly a dead end. However with some persistence I came up with Entamoeba Histolytica.
As for clean water; I use the boiling method when hiking and camping, and if you take a thermos flask along you can boil extra water while making your morning coffee and have tea or other hot beverages during the day. If you want cold water, just boil it in the evening when preparing dinner and let it cool overnight.

Greetings and thanks,


Robin writes:

Seems like Katayama's syndrome if a diagnosis is clinched in the parasitology lab.

Stool exam for cysts in amebic liver abscess is unhelpful, and trophozoites would not be expected in the absence of dysentery.

Murphy's sign as classically understood, is an inspiratory catch at the right costal margin at the midclavicular line, and not, as is now commonly described, as just right upper quadrant tenderness. The classic Murphy's sign is also well localised, and is a reliable indicator of a problem gall bladder.

Wink writes:

No, I’m the chump!!

You got me this time. I considered trypanosomiasis: the incubation would be OK but the presentation is wrong. Anisakiasis is not common there. He shouldn't have been walking around barefoot or wading in fresh water. I think the incubation for ascariasis is longer and a tourist would most likely be asymptomatic, but -- common things being common -- I'm making a wild bet on A. lumbricoides.
Wink Weinberg (Atlanta)

Richard writes:

I think that this gentleman has some sort of intestinal helminth infection, my vote is ascaris because it is soil-transmitted and the patient lacks high risk food exposures.

Further wikapedia-ing indicates that one still has to ingest ascaris eggs, but they are hard to kill so I think even the "westernized" food chain at a big hotel may be the culprit.

Else writes:

Dear TWIP Collective,

How are you? It seems that spring has finally settled in here in New York, so in spite of the high winds here in lower Manhattan (where it was in the lowest of 60’sF — 15-ish C) it has felt great.

I am again, trying my hand at a diagnosis. I know you were going for a trickier case study this time, and without a medical or science background I may be out of my depth, but here is my attempt.

I think that the young man who has recently returned from a trip to Kenya may be experiencing amebiasis brought on by entamoeba histolytica.

It was a bit tricky to think about what was going on with the patient because his symptoms were not particularly dramatic (which is great for him, but hard for this highly amateur detective), and the primary symptoms: stomach pain and decreased appetite, occur in many instances (or even without the help of a parasite, when exposed to too much family, at holiday time).

Amebiasis is apparently a common parasitic infection in many parts of the world but for the purposes of this case study, parts of Africa including Kenya and it expresses itself in many ways. 90% of people who are infected are asymptomatic. In people who are symptomatic, the symptoms can show up in 2-4 weeks, so given the duration of the patient’s visit and the fact that he has been home for a week, the time frame makes sense.

For people who are symptomatic, the range of symptoms includes abdominal pain as a primary symptom. (The patient does not have fever or other GI symptoms, but infected people don’t always exhibit these.)

As for how he could have contracted this parasite in spite of such care he took, staying at a hotel that caters to Western visitors and avoiding the water, I think it is possible that he slipped a little. It was mentioned that he ate salad at the hotel, which is raw and if it had been washed in local water, some parasites could have found their way to the patient. Also, he did drink soda, but if he had any ice cubes, again, this could have been a point of contact with the parasite. They are common, hard to avoid and it sounds like people can be colonized and have no idea.

As for the diagnosis, it is recommended that multiple stool samples get tested because the parasite can be hard to find.

I fear I have missed something critical, but this is the best I could come up with.

What was the vaccine that the patient should have gotten before he left that he did not get?

Many many best wishes. I am very grateful for your fascinating and brain-stretching (for me) podcast and challenges.



TWiP 86 letters

Jan writes:

Dear Doctors

This one is a bit more tricky; both Giardia and Cryptosporidium are possible. The symptoms are more those of Cryptosporidium, so that would be my semi-educated guess. Most of that education comes through you, with some help of some CDC webpages in this case.

Thanks for the podcast.


weather report Rotterdam:

The sky is 50 shades of grey, need I say more ?

Michael writes:

I'm guessing Giardia lamblia (beaver fever---GO OSU) even though Daniel made it sound like it wouldn't be the obvious answer. Really like this part of the show that engages the listener.

Mike in Oregon

Robin writes:

If the three stools had tests for Cryptosporidium requested and performed, then a string test might be considered.

Empiric treatment with metronidazole is not quite kosher, but might be cheaper.



Heterodont dentition has to accommodate to a changing jaw size. Hence two sets of teeth in diphyodonts.

Homodont polyphyodonts have no such problem, such as in sharks and crocs. Heterodont polyphyodonts tend to have lifespans sufficiently long to wear out the first set of "permanent" teeth, and go through life with more sets of teeth, as in the case of the elephant.

The natural life expectancy of hunter-gatherer humans is somewhere into the mid twenties and early thirties, enough for one set of "permanent" teeth. Agriculture has been around for 10,000 years, too brief in the relevant evolutionary time scales to have significant selection pressure towards polyphyodonty. And with modern dentistry and prosthodontics, selection pressures for polyphyodonty have been effectively evaded.

Elise writes:

Dear TWIP Collective,

Thank you so much, as always for your wonderful podcast. Again, I was very pleased to have had a successful diagnosis with TWIP 84. I’m not sure if I can continue my streak but here is what I suspect.

I think this young mother probably has Giardiasis, but I will hedge my bet, slightly and also say she could have Cryptosporidiosis.

Both diseases have extremely similar symptoms and are both caused by protozoa. Both commonly infect people in Colorado in the summer and early fall. Both have similar incubation periods. Both are found in all kinds of streams and lakes in Colorado.

In an effort to try to distinguish between the infections, I tried to see if either Giardia or Cryptosporidium are more easily detected in a stool O&P, but as it turns out they can both be hard to spot, even on multiple tests. (There has been much complaining online about how there is a huge and growing shortage of good lab technicians who can spot these things.) I did find a couple of sources that indicated that Giardia, due to “intermittent or low levels of shedding” might be somewhat harder to find on the O&P, which could account for why 3 tests came up negative on the patient.

Another reason I am inclined to suspect Giardia is that it seems to be somewhat more common in Colorado, that is, there are more reported cases of it. Also, it has the nickname “beaver fever” and Dr. Griffin did mention that the family saw quite a number of beaver while camping, so it seemed to be a good clue… unless of course it was a red herring, which is why I am not committing 100% to Giardia and also mentioning Cryptosporidiosis.

I was interested to see that both of these infections can resolve on their own in people who are not immunocompromised. I was also surprised to see that even though there are many many many official web sites cautioning people to bring their own water while camping or at least to filter water and treat it, there are still wilderness types who seem to think such precautions are silly and which recommend trying to drink water from fast running streams and creeks. This seems to be Asking For It.

But of course I am now dying to know what sort of infection this woman had, so I’ll be checking in regularly to see what’s what.

As always thank you so much.

Lots of rain today in lower Manhattan but they say the weather will be swell for the half-marathon (which I am not running) that is happening tomorrow.

All best

Christine writes:

Dear Dickson, Vincent and Daniel,

Another fascinating twip, from the description of the case I think the patient is suffering from cryptosporidiosis. Although the beaver reference suggested giardiasis, the symptomology didn't match as well as crypto. The onp didn't show parasites are they are often tricky to pick up and a zn stain may help locate them in stool rather than a straight wet mount, the incubation period is a little longer than I'd like if it was picked up on the camping trip but everyone is different. No treatment other than good hand hygiene ( to avoid contaminating others) and sufficient hydration is required and it should resolve within a couple of weeks. Treatment is generally for immune suppressed individuals.

Chris from brisbane where the weather is 32 degrees C, blue skies and a light breeze. (heaven).

Rebekah writes:

Hello TWiP doctors,

I have finally caught up to the most recent episodes and was planning on responding to episode 84 today, when I saw a new one was posted. For me, the crawfish was not the telling sign this was a case of paragonimiasis. It was Daniel's description of the symptoms, particularly the rust colored blood tinged sputum. I teach Clinical Microbiology for Medical Laboratory Technicians at a community college, so I am familiar with the classic presentation for some of these parasites and Paragonimus is a favorite Board of Certification question. I shall, again, be recommending this podcast to my students especially the new format should help cement the knowledge into their heads by getting them to think about real patients.

As for the case in the current episode I believe this is Cyclosporiasis. The main reason I pick this organism over Cryptosporidium or Giardia is because the x3 ova and parasite exams came up with negative results and because the other members of the house hold were not sick. Person to person transmission is unlikely with Cyclospora since the oocysts take days to sporulate and become infective. The O&P exams were likely negative because there are not many if any recognizable oocysts in the feces. Laboratories do not typically screen for Cyclospora unless there is a specific request ( since testing requires the use of acid-fast staining or PCR-based methods), therefore a routine O&P would not yield positive results. If this woman had consumed raspberries instead of drinking contaminated water it would have been another classic Boards question. :-)

This disease is typically self-limiting as long as the patient is in good health. If not she could use Trimethoprim/sulfamethoxazole, unless of course she has a sulfa allergy in which case I don't know.

Love the Podcast and thank you for all your hard work.

Rebekah MLS (ASCP)

Ruben writes:

Dear Majestic Trio,

My training was in physics and math and I will be succinct:

Google diarrhea and beaver to get the answer: Giardia (aka beaver fever).

Additional tests: order a Giardia, Cryptosporidium, or Entamoeba histolytica antigen test since the actual parasite or ova was not detected in the stool.

Treatment : albendazole or the like (see the reference below saying that it is less toxic and more effective than metronidazole).

** A suggestion for future case presentations in case my answer is right: I think the case should not not be 'googlable' from keywords or, at the very least, not lead to a single possible answer. Furthermore, the case may be sprinkled with irrelevant information and red herrings as it happens with real cases. Non-Google-singlet rule should be strictly enforced.

Daniel mentioned 'beavers' two times and, even with an apparent attempt to water it down with elks and cow feces, it was a google-give-away.

Must haves: the weather in San Diego is always the same, not much to talk about.

With deep respect and appreciation,


PLoS Negl Trop Dis. 2010 May 11;4(5)
A meta-analysis of the effectiveness of albendazole compared with metronidazole as treatments for infections with Giardia duodenalis.

Mark writes:

Dear TWiP 2.0 Team,

I've been an intermittent TWiP listener since episode #1. Intermittent only because of the variable recording and release schedule. The show is great!
This year's reboot and addition of "Doctor Doctor" (MD, PhD) Daniel Griffin to the podcast has catalyzed an exciting TWiP renaissance.

I listened to TWiP #85 today while driving home to San Jose, CA from a weekend getaway to California's Central Coast to celebrate my birthday. Over the weekend cities there, Paso Robles and San Luis Obispo, hit record high temperatures in the mid-80's. California's drought is very real.

The case in this episode is subtle and delightfully thought provoking. There are competing candidates for the parasite causing the infection AND exposure to both of them is possible. The candidates are Giardia and Cryptosporidium.

Giardia is consistent with symptoms of diarrhea. Other causal clues were the woman was camping with her family in areas where beavers, an intermediate host, were present. Tantilizingly, it was reported that the patient and family drank from streams and used iodine to treat the water. D.D. later commented that iodine had effectiveness against bacteria - so its possible Giardia cysts would be unaffected. D.D. asked about the presence of fat in the stool to which D.G. replied no fat test was done. D.D. then prompted with the word "steatorrhea" which elicited no response. Given that steatorrhea is characterized by
especially foul odors and that the patient commented about mucus in her diarrhea without commenting on smells or odors, and the negative response to D.D.'s probing it seems unlikely that the patient was suffering from Giardiasis. Finally, the patient had a temperature which is not a symptom associated with Giardiasis -- see:

So, what about Cryptosporidium?

Many forms of Cryptosporidium exist, targeting different mamalian hosts. Cryptosporidium symptoms include diarrhea and fever. Crypto is very prevalent
and can be spread via cows. Here is a webpage at the Colorado State University School of Veterinary and Biomedical Sciences about crypto:

The patient's case history indicate she and her family were camping and hiking in an area where there were a lot of cows, so many cows that she commented about how it diminished their enjoyment. Exposure to Crypto oocysts while walking is one source of infection. Another source is the incident described wherein the patient had contact with her child after who fell in cow feces.

Based on the patient's symptoms more completely matching those for Crypto, and the direct contact with cow feces I conclude the patient is suffering
cryptosporidiosis. As per the CDC - - treatment focuses on
managing the symptoms of diarrhea, ensuring replacment of fluids. In some cases Nitazoxanide may be prescribed.

All the best.

Keith writes:

Dear All,

Love the TWIP Reboot, Dr. Griffin blends wonderfully with the milieu. We have not heard a story from Dr. Despommier in a while, he is a fantastic story teller. Also from Dr. Racaniello, I miss his explanations. For example, when he briefly describe the micro inhibition test and hemagglutinin test. The cases are just fantastic, it really heightens my attention when I'm listening and makes me read and think after listening to the episodes.

Having lived and hiked in backcountry of the Rocky Mountains of Colorado the first two things that instantly jumped my mind were Giardia and Cryptosporidium. In the 90s when I lived in Colorado I was convinced that my dog had Giardia. She would have explosive extremely foul smelling diarrhea with mucus intermittently. As long as she had access to the outside all was okay but one year we did have an awful Christmas trees Incident. Let's just say I had to remove many of the branches from one side of the tree.

After reviewing the various disinfection methods in their effectiveness my guess would be cryptosporidium. Cryptosporidium is easily filtered a very resistant to chemical disinfection. Since their sole method of disinfection was iodine the most likely culprit would be cryptosporidia. Giardia is moderatly susceptible to chemical disinfection and therefore a less likely candidate.

Please keep up these case Studies.

Anne writes:

Dear TWIP team-

So enjoying the new format.
RE: TWIP 85 Patient from Colorado

Excluding bacterial and viral causes of diarrhea that would need to be considered in this patient (if we weren’t being presented the case on TWIP), Cryptosporidiosis and Giardiasis seemed the most likely based on the consumption of unfiltered water potentially contaminated with animal feces.
Cryptosporidiosis appears to be more often associated with low grade fever and watery diarrhea than Giardiasis. Also Cryptosporidium is quite a small parasite and could potentially be missed on the O and P. Diagnosis is enhanced by the use of acid fast stains and molecular diagnostics. However, the typical incubation period is 2 to 10 days after ingestion, which is much shorter than the patient reported. Does this case represent an unusually long incubation period, another source or a different pathogen altogether?

Giardiasis is less often associated with fever and the stool is described as floating and greasy. I briefly considered amebic dysentery due to Entamoeba histolytica and Strongyloides stercoralis infection, but they seemed less likely water contaminants for Colorado.

Cryptosporidiosis is a common opportunistic infection in SIV-infected macaques and often sets up infection outside the intestinal tract: gallbladder, common bile duct, pancreatic ducts, trachea, and bronchi. We’ve even seen it in the salivary gland ducts. I include photomicrographs.

Unrelated, I was delighted to see the February 2015 case of the month on the CDC website featuring a hunter with abdominal pain and difficulty breathing after consuming bear meat.

I would like to make a plug for inclusion of fungal and microsporidian diseases. They are way too interesting to exclude from the clinical case presentations.

Is Dickson phylist (adjective 1. having or showing the belief that a particular phylum is superior to another)?

Best wishes

Markedly enlarged salivary gland duct with thickened mucosa and inflammatory infiltrate.


Salivary gland mucosa is proliferative and has undergone squamous metaplasia. Variably sized Cryptosporidia are evident on the surface.


Anne Lewis, DVM, PhD
Beaverton, OR

Nancy writes:


"Beaver Fever"/Giardiasis. My grandmother picked this up when my parents lived in Fort Collins. She never remembered drinking anything not treated whilst visiting Estes Park, but was diagnosed after returning home to Reno. A lifetime western resident, she was savvy to the symptoms and felt vindicated when her doctor's lab tests confirmed her self-diagnosis. She believed she must have picked it up via washing her hands in the creek down the block from the home in Fort Collins. All this must have been 20 or more years ago.

"Sure", Dan, Fort Collins is a city. Of sorts, but quite livable, being a college town with a high percentage of college graduates.

Well, if I'm wrong it's because I'm a happy unit clerk at our local hospital's outpatient surgery unit, as my retirement job. My sole diagnostic qualifications are curiosity and long life experience.

I do enjoy all the Twixes, Twip the most, due to fewer dictionary and pubmed lookups necessary. Podcast on! and thank you for your generously donated work and time!

Richard writes:

I guess cryptosporidium Bovis. Arguing against giardia are: watery stools (not steatorrhea) and the negative studies. But giardia was definitely my first guess up till the end.

As a question for the panel: which Water-borne organisms/viruses are not killed with iodine treatment? Do filters miss anything? Boiling? Thanks guys keep em coming.

Jeff writes:

Dear TWIP hosts,

Love the new format! After weeks of speculating in my daily commute on the various cases, I am going to take a stab at the case of the week as Giardia lamblia. The focus on the beavers gave a hint as it is sometimes referred to as “Beaver fever” even though there is not typically a fever with Giardiasis (could never figure out that disconnect). The negative O&P threw me off for a bit until I did some digging and found that this is only diagnostic in ~70% of cases (J Clin Microbiol. 1989 Sep; 27(9): 1997–2002.) and the cysts are not shed in the stool on a consistent basis. Also considered Cryptosporidium as that is pretty common in that area of Colorado.

You should try not to drink the water from any streams around Durango as past mining activity left the streams with a pretty high mineral and metal content and other runoff from those activities.


Jeff Fairman, Ph.D.
Vice President, Research
SutroVax, Inc.

Carol writes:

Greetings TWiP Team,

I'm writing with a guess for the case study, and to ask how I could get a copy of Dickson's book. I currently work as a veterinary technician, but have recently returned to university in order to pursue a degree in microbiology and pathogenesis. I love your podcasts, which I discovered 3 weeks ago, and am working my way determinedly through the back episodes. Luckily between school and work I spend a lot of time commuting.

Coming from an animal health background, I immediately thought the case study was giardiasis, particularly with the repeated mentions of beavers, but that doesn't usually cause a fever. I then amended my guess (I hesitate to use the word diagnosis, since it is entirely a guess) to cryptosporidiosis. Am I close?

Enjoying the sunshine and spring flowers in Victoria, BC, Canada while listening to old podcasts,


Varun CN writes:

Greetings Professors,

TWiP 85 presented a very interesting case. I would like to do a string test (Entero-test). The stress on presence of beaver and iodine treated water makes me think of Giardiasis (Beaver fever). Am not sure how do I explain, negativity for Stool O&P examination. Am really stabbing in dark.

My guess: Giardia lamblia.

I have happened to cross this article regarding cerebral malaria. The paper suggests that the change in brain volume leading to raised intracranial pressure may play a role in fatality of cerebral malaria. I wonder if this topic is TWiPable .

Looking forward to the next case challenge..

Thumbs up to the team.

TWiX fan,

Varun C N
NIMHANS, Bangalore


Tim writes:

Dear TWIP trio,

First of all I'd like to say that adding a third member to TWIP was a great idea. I love the case studies although I can't say I have enough expertise to make much more a wild guess based off my listening to early episodes of TWIP and google searches.

I found this paper this morning and can't remember this parasite ever being discussed on the show so I though I'd forward it on. I don't have access beyond the abstract so I apologize if it's not an interesting paper.

Have a great week. I'm off to the farm to haul manure on the fields while they're still solid in the early morning cold before they turn back into their spring muddy state by mid morning.

Clinical Microbiology Reviews 2015 Apr; 28 (2) : 295-311.
Human Infections with Sarcocystis Species.
Ronald Fayer, Douglas H Esposito, Jitender P Dubey
PMID: 25715644

Anne writes:

Dear TWIP team

Wonderful case this week of the patient from Missouri. I love the shift to sharing less info about the cases (although Dickson can’t bear not to ask the question that nails the diagnosis. Go Dickson!) Wouldn’t have gotten it without the crayfish question. Paragonomiasis is the diagnosis. If it is the same species that occurs in cats and other fish eating carnivores then the infection is Paragonimus kellicotti. I have seen this in a cat many years ago. Not sure of the cat’s ‘travel history’.

Many thanks for enriching my commutes.


Anne Lewis, DVM, PhD
Diplomate, American College of Veterinary Pathologists
Beaverton, OR

Kenneth writes:

Paragonimus kellicotti?
Treat with Praziquante?

Best guess of a long-time listener, full-time layman; and someone who watched the first season of Monsters Inside Me. (Which I heard about through this podcast -- Don't actually own a television, so I downloaded the show to my computer. Thought it a tad sensationalist though.)

Hopefully I didn't miss something obvious, but I tend to listen to the podcast at work. All the TWIXs have been great company through many an overnight shift of dementia/hospice care-giving. (All my coworkers think me a weirdo.)

Loving the new format and increased frequency.
Danke, danke,
Kenneth S

Jennifer writes:

Hi TWIPers,

I'm a grad student and one of your undocumented listeners (I use the stitcher app) and I really like the show, especially the new cases! My guess for the current case is Paragonimus (due to the under-cooked crayfish).

A few weeks ago - I think it was on #83, a listener mention Bob Lane's work that shows the western fence lizards have a bactericidal agent in their blood that cleanses lyme-infected ticks. This is cool, but I was surprised that the malaria parasite, Plasmodium mexicanum, which commonly infects these lizards was not mentioned, especially with all the musings about malaria infected dinosaurs.

Actually, In the vein of looking at parasitic infections of wild animals, the malaria infection of the western fence lizard may be one of the longest running studies out there. Dr. Joseph Schall, who was my parasitology professor while I was in undergrad at the University of Vermont, has 30+ years of blood smears from infected lizards from a Hopland, CA field station and has done many studies on the impact, ecology, and clonal diversity of infection in these lizards. Perhaps you'd like to read one of his current articles or have him call into the show for comment? I wonder if lizard telomeres are shortened by malaria infection too??

Also, right now in grad school I work with the organism in which telomerase was discovered (Tetrahymena thermophila), and enjoyed the shout-outs to the Nobel winners for this. Tetrahymena is really way more interesting than many give it credit for, so I thought this episode was just all-around fantastic!

Jennifer Fricke Pinello

Allan writes:

My guess would be Paragonimiasis (P. kellicotti). Confirm with an ELISA if readily available, but that’s what it is.

Give him some of that wonder stuff that my parasitology professor back at Tulane, Barney Cline, helped bring over from the Vet’s for human treatment, Praziquantel, which sure beat what was used before it.

We have our own cousins of this on the Big Island of Hawaii, sort of our own local LongIsland/Nantucket Babesiosis. I won’t give it away so if you want, some time I’ll send you a case workup as a weekly mystery.

Keep up the good work. Best podcast on the web.


Kailua-Kona, HI

Bjorn writes:


Don't know if this is too late, but here goes (I havent listened to any later twip or read any notes, so I don't know if it's to late but I also haven't cheated :-):

The lesions and the description of the skin surrounding the lesion sounded a lot like a description of cutaneous leichmaniasis, and since the patient had been in Guyana, using the 'what does the sound of a hoof imply' rule that Dixon refered to, tells us that he may have an infection of Leichmania Guyanensis, so that's my guess. I understood why Vincent asked about the genital area, since this lesion may in fact have a been a shanker caused by syphilis, and finding one on the genital area would clearly strengthen that hypothesis. To make a diagnosis of leichmaniasis one would have to find signs of the organism by finding the organism in and around the lesion, but I don't know exactly how to do that. Treatment would probably be by stibogluconate, but this thing may in fact also heal itself given a year or so.

If this happens to be right, then I'm happy :-) I started listening to twi{m,p,v} about a year and a half ago when I was following Vincents virology course on itunes. I later took the part 2 course (how viruses cause disease) on Coursera. Now I'm taking a Coursera course on "Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases" and just finished the module on leichmaniasis :-) So if what I wrote above is correct then I've learned something from the course, and if not then I guess I haven't learned enough yet.

Anyway. I love twip, and although I certainly don't love parasites, I do find them fascinating.

Best wishes


AJ writes:

Hello DDV,

I have been a long time fan of TWiX, with TWiP being my favorite. I want to start by thanking you for all the time that you put into the TWiX series, it strikes an amazing balance between scientifically relevant, yet fun and accessible.

I’ve been interested in starting a career in parasitology and pathology for about two years, but have been rather baffled in where to start. Let me explain my background without delving into self pity. I am a 26 year old who graduated with an Bachelor degree in Ecology, Behavior, and Evolution. Before going to college at UCSD I wanted to be a marine biologist so I could swim with sharks all day and get rich (because scientists probably make tons of money, right???), but once in school I eventually drifted into focusing on entomology. I graduated with a GPA of 2.5, due primarily to a lack of attendance. I now find myself in a high paying position with a local government doing inspections (started in Agriculture inspections, due to my entomology experience, but now I do scale and meter inspections).

While my job is decent in every way, I really feel I am in the wrong place for me. I like the idea of being a doctor because I am (now) hard working, scientific minded, and like the idea of making peoples’ lives better in such a direct way. Parasitology especially calls to me in all the ways that entomology did (really, I just like learning about lifecycles that are so vastly different from ours). I am also still interested in research, as I have been for my whole life.

Here’s the actual questions…

What sort of degree program is right for me? I’ve looked a lot about getting a MD, or MSTP, or Clinical laboratory Scientist Certificate… I’m living in San Diego, so I’ve been looking at UCSD Extension programs, but I’m willing to relocate pretty much anywhere.

How do I get into such programs? With a low GPA, I know I need to retake classes, get some lab experience, and probably pass the MCAT (I have a near perfect GRE score), but without having any connections to the academic world, particularly the medical world, it’s been difficult even to find an unpaid internship. And impossible to know what effect different classes at different schools will help with getting into different schools.

What should my focus be? I know I’m interested in a huge variety of subjects, and I’m sure I will be able to blend them together, but what are the new hot topics? What are the essentials? For example, I’ve gathered that immunology has a growing importance whether you’re interested in viruses or parasites or even cancer, are there other subjects like that?

I understand these are personal questions that you can’t actually answer for me, but if you want to shoot me a short email, or even do an episode about how to get into the field I would be extremely grateful! I know you’ve done a lot of talking about how things are for those who are just starting to make a career in TWiX topics, but what about us who don’t know where to start?!

Sorry for the long windedness of this email,
Thank you for your time!


In San Diego, where it is 80 degrees, arid, with a gentle breeze.



TWiP 85 letters


Jan writes:

Dear Sirs

This is fun, and although I'm sure someone will gripe about Dicksons enthusiastic response to the crayfish, it made my life easier. I think it's Paragonimus kellicoti. As for eating raw crayfish; how drunk would you have to be ?




I'm not an expert in Dutch elm disease, I'm a treeworker. Inspecting trees for potential dangers is part of the job. So I have a working knowledge of the most common problems. Dutch Elm disease is caused by a fungus Ophiostoma and spread by beetles


The weather forecast for today in Rotterdam; heavy showers, 7 centigrade and winds up to 6 bft

Robin writes:

Thanks to Larry Page, Sergei Brin et al. and to Steve Jobs, Steve Wozniak et al.:

Like shooting fish in a barrel.

Chris writes:

Just as I was about to send you my answer of lymphatic filariasis the new twip arrived in my inbox and I was thwarted by your rapid turnaround.

I am loving twip 2.0 and I have been trying to infect others with it. I have been listening since twip started and it encouraged me to go back to uni and become a medical laboratory scientist as a mature age student. Since graduation I have ended up in cytogenetics but still look forward to each episode of the twi triumvirate.
The weather today in Brisbane, Australia is 30 degrees C with about 60 percent humidity and little wind, so a lovely autumn day.

Today's case did intrigue me somewhat, particularly with the intermittent fevers and lack of travel. The key however is the consumption of raw crustaceans.

Paragonimus sp. (most likely kellicotti in the US) metacercariae encysted within the crustacean excyst in the duodenum, penetrate the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults. The worms can reach other organs and tissues including the brain and striated muscle.

The patient has presented during the chronic phase during which pulmonary manifestations include cough, expectoration of discolored sputum, hemoptysis, and chest radiographic abnormalities. Extrapulmonary locations of the adult worms result in more severe manifestations, especially when the brain is involved (these are indicated with the visual disturbances).

Diagnosis at this stage can be by the presence of eggs in the stool or sputum. Concentration may be required, immunoassays are matched to Paragonimus westermani and may not pick up Paragonimus kellicotti (more likely in the us.) The three month delay in seeking treatment gives sufficient time for the eggs to become present for diagnosis.

Treatment with praziquantel is indicated with corticosteroids to reduce the inflammatory response caused by the dying worms (particularly important in cerebral cases).

Elise writes:

Dear TWIP Collective,

I was so excited to have heard my letter read on TWIP and to have gotten the diagnosis right that I had to plunge in again (and I suppose that is an apt enough metaphor, given the case study of the week) with another diagnosis. I am delighted to be able to play along.

I believe the 32 year-old gentleman from Missouri is suffering from Paragonimiasis— an infestation of lung flukes.

Since Dr. Griffin mentioned that this guy ate a huge raw crayfish plucked from the river (no doubt lured to its death with a bit of bologna or hot dog, which the “Floater” web sites suggest are good bait for crawfish, and which it bears mentioning, could be eaten instead of the crayfish and the consumer could avoid considerable unpleasantness), a quick Google search revealed that there was an uptick of Paragonimiasis cases in the United States starting in mid-2010. One side-effect of this small but significant rise in cases is that there were a lot of articles about Paragonimiasis in a lot of places beyond medical journals and the CDC web site. Even the “Float Missouri” web site has a page warning “floaters” (people who float recreationally, not corpses found in water) not to eat live, raw or even dead, raw crawfish.

The symptoms of Paragonimiasis are consistent with those of the patient: fever, exhaustion, cough (somewhat productive, often containing a bit of blood, which might account for the brownish sputum he has— the sputum of people with this parasite can be used in diagnosis since it contains microscopic Paragonimus eggs). His chest x-ray also had fluid around his lungs, which is consistent. Many patients have central nervous system symptoms as well, which would account for the gentleman’s headaches and reported visual symptoms (blind spots, floaty things).

According to a couple of sources, the recommended medication to get rid of the flukes is Praziquantel, taken for three days. This seems like a pretty efficient drug for something that has been making someone so sick for three months.

I do have a question about this patient’s fevers which had come and gone for 3 months, which is what causes the pattern in the fever? Is it linked to the fluke eggs being released into the lungs, their hatching, or some other part of their life cycle?

Another question I have is about why these cases started coming up more in 2010. Most of the sources I found (not just the “Float Missouri” folks) point out that lung flukes are quite common in Asia, but have been relatively infrequent here. How did this parasite arrive in large enough quantities to be noticeable? I fear the question is about the arrival of the flukes, since there is zero chance that eating raw crawfish while drunk on the river is a brand new diversion.

I hope I am right. These exercises are an absolute pleasure. Many thanks for all of your work.

Lower Manhattan is getting showered with little ice pellets now after a day of snow. I am hoping that the promise of a 40 degree F (4.4 degree C) day tomorrow is not just the weather service stringing us all along with false hope.

Many best wishes,

Dr. wink writes:

As an ID physician, I am used to being nonplussed and non-judgmental by my patients' histories. However, as a vegetarian, I was repulsed by your most recent TWIP case presentation! My guess is paragonamiasis.

The TWIP duo was always great; The TWIP trio is fantastic! Thanks.

Human Paragonimiasis After Eating Raw or Undercooked Crayfish --- Missouri, July 2006−September 2010
Weekly. December 10, 2010 / 59(48);1573-1576

Dan writes:


The case under discussion dealing w/ the 32 year old male with peripheral eosinophilia, fever and symptoms of lung infection is likely the result of the ingestion of raw crayfish as mentioned in the workup. In the US this disease would be from a parasitic infection caused by the lung fluke, Paragonimus kellicoti. So, that is my diagnosis...paragonimiasis.

My diagnosis is based entirely on a peek at the literature and specifically from a paper published in Clinical Micro Reviews (see attached pdf).

Id like to mention another point that I’ve been meaning to address since it was incorrectly stated in the podcast by Dixon.

Hibernating bears do not have circulating AFP's (antifreeze proteins). We find these in teleost fish sera in arctic waters of the No. Atlantic and elsewhere; and other organisms but not in hibernating mammals.

I studied these proteins in the 1990's. I ended up synthesizing a type I AFP from a deduced amino acid sequence published in the fish literature. This was made into a transcriptional/translational fusion to a phytohaemogluttinin coding region to subcellularly locate the fusion AFP to the extracellular space in potato plants to confer a form of frost tolerance as monitored by electrolyte leakage. You can find all of this old news in Plant Mol Biol. 1997 Oct;35(3):323-30.
Expression of a synthetic antifreeze protein in potato reduces electrolyte release at freezing temperatures.
Wallis JG1, Wang H, Guerra DJ.
Author information
A synthetic antifreeze protein gene was expressed in plants and reduced electrolyte leakage from the leaves at freezing temperatures. The synthetic AFP was expressed as a fusion to a signal peptide, directing it to the extracytoplasmic space where ice crystallization first occurs. The gene was introduced to Solanum tuberosum L. cv. Russet Burbank by Agrobacterium-mediated transformation. Transformants were identified by PCR screening and expression of the introduced protein was verified by immunoblot. Electrolyte-release analysis of transgenic plant leaves established a correlation between the level of transgenic protein expression and degree of tolerance to freezing. This is the first identification of a phenotype associated with antifreeze protein expression in plant tissue.

Sorry I dont have a pdf and the paper reprints are long gone.

I used to be a plant lipid biochemist but shifted to human lipid metabolism in the 2000's.
Anyway, AFP I's function to alter the hydrogen bonding patterns of water such that the isodiametric nucleation of the ice crystal is thwarted by the alpha helical secondary structure of the AFP that is both ALA rich and sequentially patterned with repeating THR residues which do the hydrogen bonding.
Other AFP's are glycoproteins and their is a solid literature on them even in the surigical field where they have been used to allow the lowering of the incision temperature during the procedure.Something about decreasing ROS production I think but again, this is from memory and is decades old.

Bears do not need to thermoregulate like fish in 4 degree waters. Rather they live in dens that are well above freezing and indeed their body temp never drops more than a few degrees below normal physiological if at all.

I could explain the lipid metabolic pathways by which hibernating bears convert depot fat to NADH, FADH2 and acetyl CoA but that is just beta -oxidation. Ultimately they burn the acetate in the TCA cycle in their muscles and this helps prevent muscle wasting proteolysis.

They do not carry out the glyoxylate cycle wherein this TCA bypass allows the conversion of fatty acyl carbon to mammals do this. Plants do because they express two key enzymes...isocitrate lyase and malate synthase...look this up if you are interested...microbes do this too.

OK so the final question you might have would be the following...why dont bears in hibernation suffer from ketoacidosis...I can explain this but it takes too much space on the email. If you want to know, let me know or try to tease it out of the literature.

So, NO ...bears dont have AFP's in their muscle. That is rubbish.

Also they are not enriched in other forms of paradigmatic frost tolerance mechanisms such as super high elevations of circulating carbohydrates or sugar do see this in 13 line squirrels and maybe frogs but I havent looked at this literature in close to 20 years. There was a husband-wife team..the Storeys... who did a lot of work in terrestrial animal frost avoidance but you can look that up.

I should make another comment that is always in my mind when I listen to podcasts and increasingly when I read biomed literature. [My current job involves teaching physiological biochemistry to grad and undergrad students and writing exam questions in biochemistry for 1st year medical students].The other point is...biochemistry is being increasingly avoided or diluted in the medical sciences. There are fewer and fewer investigators who know their biochemistry and classical molecular genetics. Because of this, I repeatedly encounter mistakes in reasoning and accuracy when biochemistry is brought to the front. This is radically obvious when people stumble over lipid metabolism. Too bad since we have an obesity epidemic. Oh well.

Finally, the rounding out of the host lineup with Daniel is a welcome event. Keep him on board if you can.


Varun CN writes:

Greetings Professors,

In response to the case made in TWiP 84, I would like to have a BAL (bronchoalveolar lavage) done for parasitic eggs. High eosniophil count rules out bacterial and viral etiologies.

My guess- Paragonimus westermani. I'm not sure if I also need to consider P kellicotti
Treat with 75 mg praziquantel per kilogram of body weight in 3 divided doses for 2--3 days.

The TWiP reboot keeps getting better and better. Thank you for the time spent in educating.

Varun CN
Bangalore, India.

Trudy writes:

Thank you so much for the "reboot". Love the case of the week and the mental stimulation it provides!

The unfortunate crawfish cruncher had Paragonimus or lung fluke.

I am a former public health nurse epidemiologist. I suspected a fluke almost right away. In public health epidemiologists "case classify" and don't diagnose unless a qualifying medical license is held. I used an ASM Journal via the SearchMedica app as well as a search via the Medscape app which resulted in a link to this article:

Paragonimus kellicotti Flukes in Missouri, USA
Michael A. Lane, MD, MSc; Luis A. Marcos, MD; Nur F. Onen, MBChB, MRCP; Lee M. Demertzis, MD; Erika V. Hayes, MD; Samuel Z. Davila, MD; Diana R. Nurutdinova, MD; Thomas C. Bailey, MD; Gary J. Weil, MD

I copied the recommended Tx from the CDC website:

Praziquantel is the drug of choice: adult or pediatric dosage, 25 mg/kg given orally three times per day for 2 consecutive days.
Alternative: Triclabendazole, adult or pediatric dosage, 10 mg/kg orally once or twice. For cerebral disease, a short course of corticosteroids may be given with the praziquantel to help reduce the inflammatory response around dying flukes.

Triclabendazole is not commercially available in the United States, it is not approved by the Food and Drug Administration. However, it is available through CDC, under an investigational protocol."

The biggest hint to me was the ingestion of raw shellfish!
Thanks again for your super podcast!

All the best,

Naples, FL

John writes:

TWIP Tri-(per)-fecta,
I love the new TWIP format -- both the case studies and the more frequent episodes. Keep them coming!

I particularly enjoyed the Big Foot episode (#84). Your discussion of the tsetse fly paper had me laughing out loud. Fortunately, it's Spring break here at Creighton University and no one was around to hear me.

I also enjoyed your discussion of the case study, which included several engaging factoids and anecdotes. I'm currently teaching Zoology and we recently covered Wuchereria. Next time I teach it, I'll be sure to include some of these stories. Students remember the material better when it's accompanied by interesting narratives. The great thing about parasitology is that it's more than biology. It touches on so many different subjects and disciplines. To paraphrase your Car Talk counterparts, parasitology is historical, folklorical, economical, pharmacological, socio-political and pathological.

Finally, I'd like to take a stab at the case study. I believe this man is infected with Paragonimus kellicotti, which is a common lung fluke in the midwest. The symptoms (fever, low energy, aches and brownish sputum) are consistent with paragonimiasis. Diagnosis can be confirmed by ID'ing eggs in the stool or sputum. The man can be treated with praziquantel. He also needs a good dope slap for eating raw crayfish!


Ken writes:

Hi Vincent, Dickson and Daniel,

Episode 85 (Bigfoot) was yet another good episode. I am looking forward to the case studies each week. It is a great way to learn about parasitic diseases. My guess for this week is Paragonimus trematodes. Dickson's leading questioning of Daniel and focusing on crayfish pointed me to it. I found this highly relevant article from a 2010 issue of Food Safety News.
Testing of stool and sputum samples should be able to reveal eggs. A more expensive approach would be a CT scan of the lungs to look for the flukes. If flukes or eggs are found and Paragonimus is confirmed then Praziquantel would be the prescribed treatment.

Here's hoping that I might be able to win a TWiP mug :-)

Best wishes from Ken

Keith writes:

Paragonimiasis kellicotti, commonly known as lung flukes. Would explain the fevers and lung involvement and eosinophilia. Could look for eggs in sputum or bronchoalveolar lavage fluid, pulmonary biopsy, serum for antibodies by ELISA. Parasites could travel throughout the body, to the brain causing nerve symptoms, under the skin causing moving nodules, to the heart, pericardial effusion. Treat with 75 mg praziquantel per kilogram of body weight in 3 divided doses for 2--3 days.

Sorry very short. I love the cases I love TWIP. The addition of cases every week is fantastic. Please keep TWIP and the case of the week coming. Although this email a short at least you know people are listening learning and enjoying.


Andrew writes:

Hello TWiP, my name is Andrew. I'm a 23 year old programer who works for a tiny company named Menards. Actually, we're third largest home improvement company in the US..but that's not important. I was writing today to mention that I listen to TWiP and TWiV as often as I can. I greatly appreciate that you three take your time to supply everyone with so much in depth information. I'm also a huge fan of the the new reboot to the TWiP show. Daniel is a great part of the team and really meshes with you two. The case of the week is by far my favorite thing at the moment. I know nothing about the medical aspects, but I thought I knew this weeks answer. Dracunculiasis (guinea worm disease) was/is my guess. This was until Daniel started to explain that the gentleman wasn't feeling any pain. I look forward to hearing more information about this case, and many more in the future. Oh yeah, it's currently -11 degrees celsius and when I went into work today it was -22 degrees celsius.

Mike writes:

Dear Drs. Racaniello, Despommier, and Griffin,

First let me express my great appreciation for the effort you put into these excellent podcasts. I discovered TWIP, TWIM, and TWIV a month ago and they quickly become my daily routine while driving to lab. With so many episodes I am like a kid with a giant ice cream sunday too large for me to eat. Fortunately you seem less likely to melt. As I am immunology graduate student focusing on the immune response to H. capsulatum, I feel the only thing lacking is a TWIF podcast (this week in fungi)!

I would like to make a guess for the recent TWIP case study: filariasis, caused by Wuchereria bancrofti worms clogging up the patient's lymphatics. The dramatic, chronic, non-pitting, painless swelling of the lower leg is very typical. The open lesion is not so typical, but could be caused by a secondary infection. Blood smear should be diagnostic and cheap.

Connecting this guess to the earlier TWIP podcast describing M.bovis in cape buffalo, I would recommend the recent paper "Filarial Infection Modulates the Immune Response to Mycobacterium tuberculosis through Expansion of CD4+ IL-4 Memory T Cells" by Chatterjee et al in JI. Patients with filariasis had an increased percentage of CD4 T-cells producing the cytokine IL-4 in response Mtb antigen. Il-4 is a TH2 cytokine and maladaptive in tuberculosis.

Finally, I'd like to recommend that your podcast delve a bit more into the shifting labyrinth of CD4 T-cell polarization. The generalization that TH1 cells induce cell-mediated immunity while TH2 cell are immune regulatory and/or induce antibody-mediated immunity is somewhat outdated. TH1 cytokines are important for controlling intracellular pathogens and promoting IgG2a; TH2 cytokines are important for clearing helminths and promoting IgE. However, the role of Tregs for immune regulation and TFH for antibody production are needed for the full picture. [Perhaps you could convince an expert labyrinth navigator to join you for an episode. John O'Shea would be great if you can get him.]

All the best,

University of Cincinnati MSTP
UC/CCHMC Immunology Training Program

Varun CN writes:

Greetings Professors,

In following up with the case presented in TWiP 83, the case description looks similar to elephantiasis. The lab tests that I would ask for is his Blood counts and especially Absolute Eosinophil count and Giemsa or Leishman stained blood smear for sheathed microfilaria. I would also look for wet blood smear, to look for any slashing motile microfilaria. Wish I could see the patients leg photo.

My guess of pathogen- Wuchereria bancrofti

Thanks for all the shows and I simply love "TWiP reboot". You guys are simply awesome.

Thank you

Varun CN

Adam writes:

TWiP team,

Is elephantiasis too simple of a diagnosis for the case presented in TWiP 83? The fact that the scrotum did not swell makes me skeptical, but maybe the worms didn't impede lymphatic flow enough proximal to that area to cause swelling? (Which raises an interesting question: Is gravity - in opposition to lymphatic flow - ultimately the reason why elephantiasis usually occurs in the lower limbs?)

My mom was a clinical microbiologist at UC Irvine and I will never forget flipping through one of her books when I was no more than 10 years old. I came across an image of a man with a gigantic leg and was transfixed. Later, she had to explain that this was what was called elephantiasis. With my youthful imagination, I promptly decided that this condition was caused by a disease spread by elephants! I suppose knowing the actual science behind it - parasitic life cycle, pathophysiology, etc. - is equally fascinating.

Short aside: I teach middle school science in Chicago and your podcast trifecta keeps me intellectually stimulated, makes my commutes go by quickly, and gives me lots of cool things to share with the kids every single week. It's snowing here now, but you probably could have guessed that!


Suzanne writes:

I'm sure someone else has written in, but I believe the character Klinger was supposed to be Lebanese. I do remember he was from Toledo and a fan of the Mud Hens. He was one of my favorites as a kid. Actually I might have counted the whole cast as favorites. I loved that show and learned a lot from it from what kimchi is to being more tolerant of others. Along with a good respect for the science of medicine and surgery. It was a great show to grow up with.

Tim writes:

First - Thank you for the TWIx podcasts. I enjoy them all.

Second - it is great to see the TWIP crew expanded with the addition of Daniel. I also very much like the new case-of-the-week segment. Alas, this week’s mystery parasite has me stymied, but I find it intriguing as much for learning more about the diagnostic art as for the specific parasite.

Third – Yes, in a past TWIP Dickson did explain at length why the “P” in TWIP should be “parasitism” instead of “parasitology”. It seemed to make good sense at the time, although I cannot recall the specific episode.

Fourth – In this last TWIP (#83), as has happened at one time or another on all the TWIx podcasts, there were once again some questions raised which took the form of “why” questions, and in response there was the admonition that (to paraphrase) “we don’t ask why questions”. I find this apparent proscription of “why” questions across the TWIx realm (and presumably therefore in biology in general) troubling.

To ask “why?” is to elicit a response “because…”. In science it seems to me that “why X?” is the fundamental question to ask, for its intent is to elicit the causal entailment structures underlying X. Without the causal structures, we have merely lists of data and phenomena, but no organizing principles or explanatory power. It is only with hypothesizing and elucidating the causal structures that we have organizing principles and explanatory power – that we have science.

Imagine asking a physicist “why does the cannonball arc as it travels through the air rather than travel in a straight line?” and the physicist responding “we don’t ask why questions in physics”. Or asking a geologist “why is the top of that hill rounded in that manner?” and the geologist responding “we don’t ask why questions in geology”.

Of course those would be absurd conversations, because those are perfectly valid questions and there are perfectly valid answers that involve the causal structures involved on those scenarios.

There can of course be unscientific answers to “why” questions. For example, “the hill wanted to be less angular so it became more rounded”. But such mistakes surely do not, and cannot, lead us to eviscerate “why” from the scientific enterprise.

It seems that perhaps in the struggle to shed itself of an inherited legacy of vitalistic, anthropomorphic, teleological and religious of answers to “why” questions, biology has chosen a linguistic strategy to avoid such categories of answers by simply prohibiting questions of the form which may lead to such answers.

It is perfectly valid to ask “why did organ X evolve in species Z?” To deny this is to deny the role of causal entailments in biological nature; in effect, denial of these kinds of questions as being scientific leaves a void to be filled with NOTHING BUT vitalistic, anthropomorphic, teleological and religious answers. Whether or not we currently have in science sufficient data or robust answers to such questions is quite beside the point that the question is valid.

If need be for palatability, such questions can be temporarily reformulated as “what” questions. “Why does the cannonball arc as it travels through the air rather than travel in a straight line?” can be rewritten as “what are the causal entailments structures that underly the phenomenon of the cannonball arcing as it travels through the air rather than traveling in a straight line?”

Similarly, “why did organ X evolve in species Z?” can be rewritten as “what are the causal entailment structures underlying the phenomenon of the evolution of organ X in species Z?” Surely no TWIxster can deny the scientific validity of this question. (Again, the tractability of this particular question is beside the point.)

Such “what” reformulations leave us with an answer in the form of an enumerated list of causal entailment structures. This is by itself not enough. In this sense, “what” is more passive than “why”: ultimately, we want to return to answering the “why” by taking those enumerated causal entailment structures and employing them in logico-mathematical models and leveraging the explanatory powers they can provide. Thus it is that science is ultimately concerned with “why” questions and the answers they generate. Evading unscientific answers to questions about physical phenomena, such as organisms, by evading “why” questions would be, I think, quite destructive to science.

Once again, thank you for the great podcasts that are so helpful, entertaining and informative!


Robin writes:

Can ‘extinct’ be used as a verb?

Mary writes:

Dear TWIP,

1) Part way through episode #84-Bigfoot, I cannot help but wonder this. If the substance secreted by the filariae that "inhibits division endothelial cells of the lymphatics," mentioned by Dick, were isolated, identified, and its mechanisms determined, would we be looking at a possible applications for cancer treatment?

2) My career goal is to become a Registered Diagnostic Medical Sonographer. I will be on the look out for parasitic worms from heretofore.

3) This is my first TwiP episode, and I usually listen to TwiV during weekends at work. As a receptionist, I'm chained to a phone in a mini plexiglass fortress. Your podcasts are a delight while attending to bureaucratic paperwork.

4) Can you suggest a social platform (twitter, etc) to broadcast questions like item #1? I have no problem exposing my scientific naïveté in a public forum. It seems like a waste to have my curiosities disappear completely. Given a financial situation* that prevents the education needed for a career with serious bench work, I want to throw my ideas to the wind and have the professionals sort it out.

*Though during retirement, I fully intend to take advantage of free community college classes offered to seniors.


Keep up the great podcasts. You wonderful folks connect science to the public and that is a noble service indeed.


TWiP 84 letters


Jesse writes:

Doctors TWiP,

I liked the discussion of the interaction of bacteria and Leishmania in sandfly guts; it was very interesting! Here is another suggestion if you need a topic to discuss:

Delivery of a functional anti-trypanosome Nanobody in different tsetse fly tissues via a bacterial symbiont, Sodalis glossinidius



TWiP 82 case:

Allan writes:

My guess is: Malaria (most likely P vivax or P oval).

On another note, I listen to TWIP while driving home on the Sticher phone app, which much like a radio, lets me listen to a list of my favorite, frequently updated podcasts (news & health-related in my case), and alerts me when there is an updated episode. The audio podcasts are small enough that I stay under my allotted cell minutes and don’t have to download or delete episodes. I actually discovered TWIP via the Sticher app about three years ago, and while I have no financial connection to the app, had never heard you mention it as a conduit for TWIP.

Keep up the good work.
Kailua-Kona, Hawaii

Richard writes:

My guess is P. vivax malaria. The patient has fever every other day (tertian fever) with shaking chills, general malaise and headache, and the labs are all consistent with malaria. This could be either a recurrence (with the symptoms of the primary infection masked by mefloquine treatment) or a long incubation period (maybe due to the thalassemia minor). Either way a 6 month asymptomatic interval is, I think, not unusual with vivax. Add primaquine!
Columbus, OH

Richie writes:

Hey guys, I am loving TWIP 2.0! I am a medical student considering a career in infectious disease and tropical medicine in particular; TWIP was always great but the added clinical component has improved it. I also love the commitment to more frequent episodes.

Regarding the case presentations: I like the structure in #82 with Daniel supplying the basics and Dickson and Vincent asking follow-up questions, but is there any way you guys could limit the "guessing" at that point? I personally think it would be more fun to just present the history and selected other findings, and then save the differential diagnosis for the following episode. For example, the discussion of the first and second cases included the correct diagnoses. I don't yet know the answer to the third case but I was pretty sure it was vivax even before Dickson began talking about why that was probably it. I think it would be more satisfying to form a diagnosis from the presentation alone. If I'm wrong and it is not vivax, well, that undermines my point entirely and please disregard this email.

Columbus, OH
9F, -13C

TWiP 83 case:

Jan writes:

Dear doctors,

Thanks to google, I think it's lymphatic filariasis, transmitted by the culex mosquito. Love the (twix) show(s) where I learn a lot outside my normal field which is trees. We still are in the dark ages there. Our treatment options after diagnosis are rather limited; improve the soil, let's wait and see, amputation or euthanasia. Sadly it's mostly the latter due to economic reasons.

ps The weather here in Rotterdam, the Netherlands is 7 degrees centigrade and showery, wind is not too bad for a change.

Elise writes:

Dear TWIP Trifecta,

I am a longtime fan of yours and think you’re terrific both as a duo and a trio. Thank you so much for your work. I am not a scientist at all, but I love listening to you and do my best to follow both TWIP and TWIV out of pure interest.

Of course I have been following along with your recent case studies and have taken notes and done my own, non-scientific, non-academic, searches to try to diagnose these patients. I was privately pleased that I figured out the Babesiosis diagnosis in the gentleman on Long Island by myself but did not write in due to embarrassment.

With this new case, I am feeling reckless, having gotten one right. I think the gentleman from Guyana may have Lymphatic Filariasis. Here’s why:

The nematode worms that cause the disease are common in Guyana and this gentleman didn’t drink filtered water or take other precautions.

An infection can take years to manifest while the worms multiply and many infected people are asymptomatic, so he wouldn’t have had cause to complain about much, which he hasn’t done (and in what is behavior somewhat typical of many men I know, he still didn’t feel he wanted to do much about it even with significant swelling and an open wound).

Dr. Griffin did say that the man’s genitals were normal, and while it is apparently common for the genitals to also become swollen, perhaps this man is fortunate (since not all people who are infected have this symptom), or the disease had not progressed.

The edema described in patients with later stage Lymphatic Filariasis matches the sort that Dr. Griffin described, non-pitting and “brawny,” with skin color and texture changes.

In reading about Lymphatic Filariasis, I was a bit confused because there is not always a mention of a chronic abscess or wound, but apparently a single abscess can be caused by collections of dead worms on the lymphatic tract, so that symptom fits.

I was interested to see that, for diagnosis, blood collection should be done at night because that is the time when the microfilariae are circulating. Does this mean that diagnoses are often missed because blood is most often drawn during the day or is there so much suspicion about what is causing this constellation of symptoms that medical practitioners know to draw blood for this diagnosis in the evening hours?

Thank you very much for your webcast. If I get this wrong, I hope very much that my having written is not something embarrassing (to me), and if I get it right, or close to right, or wrong in an interesting way, perhaps it is due to the way you explain everything so well and are such good teachers that even someone with no training could play at-home detective.

It is very cold here in Lower Manhattan where I am right now, -5C, 23F.

Best wishes,


Ken writes:

Hi Vincent, Dickson and Daniel,

I have been listening to the TWiX series for a long time, and even got to experience the TWiV bump by appearing in an episode of TWiV when Vincent visited MedImmune last year.

Having done postdoc work in a trypanosome lab at the Univ of Buffalo, I particularly enjoy TWiP and am really enjoying the recently revamped format. During episode 83, you were talking about primaquine and a MASH episode in which it was discussed. The character was Klinger, who was a Lebanese American. According to what I found on Wikipedia (not always a reliable source, but I think in this case it is) hemolysis is an adverse effect of primaquine in Africans or Caucasians of Mediterranean descent.

Also, I wanted to take a stab at the case study in episode 83. My diagnosis is lymphatic filariasis due to Wuchereria bancrofti. I would recommend doing blood collection at night since the filaria circulate at night in the blood and then doing a smear for identification.

Looking forward to more excellent episodes of TWiP!

Best wishes

Wikipedia entry for primaquine

Curt writes:

Hello all,

Didn't write in last week because the time course threw me off of malaria, which was my only suspect. The epidemiology, time course, and some of the syndrome is right for elephantiasis secondary lymphatic filariasis. However, while lymphatic filariasis may produce numerous bacterial infections, I would anticipate these to either be short-lived or ultimately proceed to sepsis. As such, I anticipate that the persistent, unhealing, painless wound would demonstrate leishmania amastigotes under tissue sample light microscopy.

At this stage in the disease, it's clear that at least some of the worms have died, which complicates testing, but he may show some microfilarea in a thick blood smear if the sample is taken at night and some worms persist. Check for splenomegaly and preform an Ig assay to rule out visceral leishmania, refer the patient to a lymphatic specialist for possible elephantiasis therapies, active filariasis has been known to respond to doxicycline (since we're on the cheap), and treat the leishmania with miltefosine.

Wink writes:

At 1:11 I'm saying Wucheratia bancfofti.
Wink from Atlanta
(P.S.: The vivax was at 9 months)

Bill writes:

TWIP Trifecta,

I love the new format with the case studies.

I came across the TWIX trio a few years back, and they give my mind a welcome diversion during my commute to and from work where I spend my days managing a team of talented engineers in the auto industry.

I was disappointed to see just one response to last weeks case, so I thought I would give it a shot.

This weeks case sounds like lymphatic filariasis - a.k.a. elephantiasis. It is recognizable by Lymphedema - commonly called big foot. The decreased lymph system function causes the build up of fluid, and makes infection more likely. The open sore seems to be a secondary bacterial infection.

Regarding tests to schedule, I would like to see a thick blood smear with a H&E stain collected as late as possible - this should help to confirm the presence of microscopic nematodes.

There are currently three known vectors – Aedes aegypti, Culex and Anopheles – in Guyana that can transmit the disease. Vincent's question on the swollen genitals would suggest ruling out Wuchereria bancrofti, but in my literature search, it was not clear if Brugia malayi and Brugia timori are prevalent in Guyana, so perhaps it could still be W. bancrofti.

On to treatment, Diethylcarbamazine (DEC) looks to be the drug of choice. An alternative could be ivermectin to kill the microfilariae with doxycycline to take care of the adult worms.

For the open wound - antibiotic to clear the infection.

Many Thanks,
Buffalo, New York.

Weather - Very cold, lots of snow but no risk of mosquito bites.

Jesse writes:

I really enjoy TWIP, both the entertaining banter and the science. I particularly enjoy Dick's expositions on the myriad parasitic ecologies. Daniel's clinical expertise is a welcome compliment to Vincent and Dick's tributes to Abbott and Costello. Thanks Vincent, for supplying Dick with a new microphone and coaching his microphone technique. As a turnabout, a video of Dick teaching Vincent how to cast with a fly rod, while unrelated to parasitism, would make for bemused viewing.

Here's my take at episode 83's listener quiz. From perusing my wife's medical references I'll venture that the Guyanan gentlemen with the discrete travel plans is suffering from lymphatic filariasis. He has probably been infected for many years as the swollen leg's skin has "brawny" characteristics.. According to my reference text the lack of genital involvement, swelling limited to the lower leg, and an ulcer along his inner shin point to an infection by Brugia malayi. I don't recall Daniel's physical exam mentioning enlarged popliteal lymph nodes but I imagine they were present.

I look forward to listening to your next episode to learn if my guess is on the mark. Thanks again for a great podcast.

Robin writes:

My four episodes of malaria were in childhood before my teens, in East Pakistan (now Bangladesh) and West Pakistan (now Pakistan). That's the closest we come to cohabiting with a photosynthetic organism: the malarial parasite is descended from a lineage of photosynthetic Dinoflagellates and still carries in its genome a few vestiges from its ancestral photosythetic machinery.

A far cry from corals and free-living non-photosynthetic microbes which associate with photosynthesisers that act as symbionts, endosymbionts and even become acquired organelles.

Some New Guinea tribes had a 95% prevalence of asymptomatic malarial parasitemia in adults. The prevalence among adults in Gambia was 70+%. If in deep time past the parasite could have found a way to ride along through the vertebrate germ cell line, they might have found a way to earn their keep, and become an endosymbiont.

Old wives' tales: these are best spread by GYN specialists.

Swollen leg: The patient usually does not worry if the condition is painless.

Night time thick and thin blood smears from a finger stick, Giemsa stained, could be examined.

First thing to treat elephantiasis is a course of penicillin or other related drugs if the patient is not allergic to them. Prompt attention with treatment for episodes of local cellulitis and special attention to local hygiene and cleanliness to prevent cellulitic episodes can be very helpful.

Albendazole with ivermectin should deal with the microfilariae. Doxycycline against Wolbachia should permanently eliminate microfilariae and halt progression of elephantiasis.

If the ulcer looks like leishmaniasis and shows no improvement with PCN, a PCR is in order, but since it is not reportable, neither the CDC nor the state health department would be persuaded to pick up the tab. The physician may bill TWIP (Take What Insurance Pays) but the laboratory service is another matter.

Meanwhile fluconazole may be an option until laboratory results. Miltefosine may be a consideration then.

Oscar writes:

That was a sneaky way to get someone to listen to the back episodes! Well played Dr. Griffin, well played.

Also, keep up the experimentation! You all have good instincts, follow them. The world needs a new cartalk (weekly, enlightening mysteries). You could do it. At least three different mysteries presented and solved per episode. There are some back episodes where Dixon and Vincent trade off questioning each other through the whole presentation and it really works. Instead of the car talk guys questioning the listener you question each other and it steps the listener through the paper.

Here are some free ideas--instead of 'case' or 'paper' or 'presentation' I'm going to use the term 'mystery'.

1. All three of you should laugh at least three times per episode.
2. Instead of listeners call in, have a 'smarter person than us' call out (perhaps to enlighten a mystery or present a mystery or share news or report on location), that parasitalogist from Mayo--Bobbi Pritt, that you had on a couple months back would make great regular--not too often and not too long--like when some professor from MIT would call in to yell at Tom and Ray.
3. Figure out what kind of mysteries the bit you're doing is--figure out some sort of taxonomic classification. Get a few solid kinds so you and the listeners can start to catch a rhythm.
4. Know how much of the mysteries you want to give away going in.
5. Have at least one mystery that goes on for more than a week, maybe an easy and a hard one. Perhaps the 'smarter person than us' could give all three of you a mystery that is outside your expertise and even outside the scope of parasitology. The Car Talk hosts weren't afraid to blindly grasp for an automotive engineers solution to a relationship problem that had nothing to do with cars--you shouldn't either--it keeps you extra human.
6. Here's a mystery presentation idea: 'One Question'. Give a really short background and have people email (or perhaps fill out a form) where they get to ask a question and take a guess. If they get it the first week on the first question they get lauded. If they ask a question and guess wrong it goes to the next week with a new person where the short presentation (one or two sentences) and then a summary of all questions and the new person gets to ask a question and guess. The longer it goes the better the prize? If all three of you took turns coming up with the mystery you could compete with each other as well as to who could stump the listeners the longest.... oooh... I like 'stump'. Maybe you could call it 'Chump-The-Stumps!' for a shameless-but-not-copyright-infringing homage to Cartalk.
7. Have fun!

Eagerly listening,



TWiP 83 letters

Robin writes:

Malaria: shaking chills & fever (followed by sweats, not specifically mentioned in this case), is a characteristic of malaria that is unforgettable once one has had it (I had malaria four times).

Thick blood smears is de rigueur.
Some helminths will also produce a similar syndrome. Forgot which ones.

Some of the things every physician should have been taught to familiarity (not necessarily competency or proficiency): (These include the use of a microscope)

Wright's stain blood thick & thin.
Ziehl-Nielsen stain sputum.
Gram's stain all & sundry.
Scotch tape for ova.
Hanging drop for trypanosomes.
KOH prep for hyphae.
Wintrobe haemocytometer manual CBC.
Spun hematocrit.
Silver stallion sigmoidoscopy.
Endotracheal intubation.
Indirect laryngoscopy.
Reduction of easier dislocations.
Slit lamp examination of the eye.

Robin writes:

Horizontal gene transfer between eukaryotes?

Steve writes:

One for Dickson: Dolphins can carry a parasite in the part of their blubber most likely to be bitten by sharks, because part of the life cycle is in the shark.

Keep them coming. (y)

And thanks for your kind reading of my letter on TWiM, that was a nice surprise.



Marcia writes:

I’m sure others have pointed this out to you already, but this was an interesting article:

On another more trivial subject, why is the title of the show “This Week in Parasitism”, and not “This Week in Parasitology”? When I was growing up, my mother worked in a hospital lab, and that department was called “Parasitology”. One of your other podcasts is called “This Week in Virology”. Just wondering why the different nomenclature.

Thanks for all the enjoyable episodes. It’s fun to learn new stuff.

Dani writes:

Hello Twip Musketeers!

I love the new case of the week, thank you for this most interesting addition to your educational empire.

I am e-mailing today about lizards and lyme disease, I've recently learned that some lizards that are a host for tick nymphs actually clear the nymph of the lyme spirochete. Nature amazes me! I've done a literature search looking for information on the biochemical basis for this phenomenon with no luck. What do you guys know about this? Is this phenomenon useful for trying to manage Lyme?

The weather is 16 C in sunny Cupertino, but I prefer the rain. Thank you for the fantastic podcast!


TWiP 82 letters

Allan writes:

Dear Vincent, Dickson and Daniel,

I like your idea of a TWIP coffee mug prize (or maybe a mug discount).

In this second case study you presented, the present symptoms are pretty vague, but his history is interesting. Also since with this podcast you’ve given us license to hunt for zebra’s…particularly parasitic ones...

I would want to rule out Rocky Mountain Spotted Fever common in Long Island, but with the presence of regular blood transfusions and a spenomegaly in his history makes me think you were highlighting something more. I would want to also test for transfusion-associated Malaria, dengue and babesiosis.

Although normally vanishingly rare as a transmission route in the US, the fact he’s getting monthly transfusions, moves this route to just very unlikely. I think there were several dozen transfusion-associated Babesia cases back in 2002 and I actually thought the US was testing for it now. Otherwise its just opportunistic if around cattle and deer ticks. Between malaria and dengue, I doubt the patient would describe dengue as just fatigue, malaise and stomach upset. I’ve had both and dengue hurts worse than that.

So if I had to guess, it might just be Malaria (non P. falciparum).

I look forward to learning more from you three in such an entertaining forum.

Best regards,


Allan Robbins, DIH, MPH
University of the Nations
Kailua-Kona, HI

Curt writes:

Hey TWiP gang, loving the new format. This case sounds like a dead ringer for transfusion acquired malaria. Test by PCR or slides, treat with antimalarials.


Robin writes:

A case of transfusion-carried malaria.

Anne writes:

Dear Daniel, Vincent and Dickson,-

I have only recently discovered TWIP and the other TWIX and have been avidly listening to both the current episodes and catching up on the earlier ones (if only I had a longer commute.) As a veterinary pathologist, it has been a delight to hear about diseases and pathogens near and dear to my heart and training.

Regarding the second clinical case presented by Daniel on January 24, 2015:
I considered Babesia microti and Anaplasma phagocytophilum high on my list of differentials which included all of the diseases discussed on the show: Babesiosis, RMSF, and malaria plus anaplasmosis, ehrlichiosis, typhoid fever, and even bartonellosis. Given the patient’s history of regular blood transfusions, the issue of whether the infection was acquired through tick bites was less important than whether a classically tick borne infection could be acquired through the blood supply. Similarly, although several of these are not caused by ‘eukaryotic parasites’, I figured they were still fair game since RMSF had been thrown in the mix.

A diagnosis of infection with Babesia microti is supported by the generalized and vague signs of illness, fever, history of asplenism, dark urine, mild elevation of liver enzymes, and geographic location of patient. Similarly, these findings would also support a diagnosis of human granulocytic anaplasmosis (HGA) for which transmission through the blood supply has also been documented. Favoring consideration of HGA is the presence of thrombocytopenia as well as anemia. Were morulae observed on the blood smear?

Although the presence and nature of a rash would not have been diagnostic in and of itself, it is a sign to be considered in several of these diseases.

Looking forward to hearing the answer.

Anne Lewis, DVM, PhD
Diplomate, American College of Veterinary Pathologists
Head of Pathology Services
Beaverton, OR

Robin writes:

Dear Doctors of TWIP,

Long time listener to all of the shows, first time writing to you.

My guess for the case presentation is babesiosis, aquired via blood transfusion. That is what will be seen on the smear I suspect.

I very much enjoy the clinical application aspect of the show. I am a registered nurse (32 years) and amatuer biologist. Dickson's anecdote regarding the effectiveness of freezing bear meat will make for great nerd cocktail conversation. Thank you Dickson!

As part of my job I am resposible for monitoring and following approximately 50 patients per month for possible blood stream infections secondary to vascular access devices for example PICC lines.

I also recently "diagnosed (thanks to TWIV)" a collegue with dengue from travel history and symptoms. I use word diagnose in the loosest possible sense.

Your shows have been a great source of learning for me. Thank you for sharing your time and talent with all of us.

Kind regards,


Varun writes:

Greetings Profz,

There is often a reference made to the connection between Toxoplasma and Schizophrenia, which has come up again in TWiP 79. There is a great deal of debate in literature. I have also blogged about it sometime ago. I have referenced Vincent's page in the post. As someone currently doing some experiments in psychoneuroimmunolgy of schizophrenia, I'm currently looking at it. Keeping my fingers crossed.

Second point that came up in response to letters was regarding methanogens. As you know there is a huge interest in "microbiome", and methanogens is also one of them researched upon. There was a correlation made between M smithii and Obesity. I have blogged about that also a time ago. I'm not aware of recent developments though.

Last but not the least, I enjoy Dickson's every episode. He is an excellent science narrator. I (With thousands of others around the globe) just wish, he keeps giving more shows and gets TWiP100 within the end of 2015. As always, you profz are excellent educators.

Thank you for your podcasts,

Varun C N

Junior Research Fellow
National Institute of Mental health and Neurosciences
Banaglore, India

Peter writes:

Dear TWiP hosts,

Congratulations to your new addition. I am looking forward to future TWiPs with more clinical perspectives.

Speaking of which, are you considering to get Alfred Sacchetti on TWiP?
He has been on TWiV and TWiM; two of my most favorite episodes. It has been a while: TWiV 132: Virology 911 on 08 May 2011 and TWiM #22: Microbiology 911 on 14 Dec 2011.

If there are not enough parasites in the ER to fill a show, maybe he could also return to TWiV and/or TWiM.

I really would like to listen to a show Parasitism 911, if there is enough to talk about.

And lastly, from 09 Feb 15 Duke University's course Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases starts on Coursera (see I enrolled and hope to find the time to keep up with the course during the eight weeks of study.

Thanks for all your work.

Kind Regards from Incheon (Korea),


Cindy writes:

I am sitting here listening to the newest twip that happens to be "living in a wormy world" and watching tapeworm segments crawl out of my sleeping dog's bottom. Fascinating. Definitely time to get to the vet, the dogs have been catching and eating rabbits lately. I'm thinking Taenia pisiformis. Sometimes I wish life wouldn't so closely imitate art.

Anyway, thanks for the informative podcast. I think it is responsible for desensitizing me enough so I didn't lose my lunch.

TWiX is reaching people like me, a non-scientist stay at home mom who enjoys following science as a hobby. Along with "Skeptics Guide to the Universe" they are my most eagerly anticipated podcasts.

Steve writes:

Hi Vincent,

First let me say that I'm totally addicted to your podcasts, and often find myself listening to them almost round the clock. I'm pretty much housebound with a long term illness, and you and Dickson, and the team, make a great contribution to keeping me the right side of sanity. You must be providing one of the best scientific educational resources on the Web: long may you continue.

For want of science literate doctors in the NHS, I've been dumped in a pigeonhole labelled either 'ME', or 'hypochondria', depending on the preferences of the GP one sees. I think that both are just handy labels that get the profession off from proper consideration of all the signs and symptoms, and that the majority of people like me would be properly diagnosed if only they could deal with scientists instead of GPs.

In this respect, I find myself quite envious of those who come to your research hospital and get the kind of careful consideration shown in your new case studies. If only there was somewhere like that here in England, but I'm afraid there is very much an anti-scientific, anti-testing culture in the medical profession here: the more clues, in terms of signs and symptoms you provide, the more likely you are to be called a hypochondriac without considering them at all.

Anyway, it's good to know *somewhere* there is a scientific approach!

Because of this curious anti-science attitude here, a number of patients have actually started to conduct their own investigations, and I thought that Dickson in particular, might like to look at the link, below, to some of the microscope work that one of the more gifted patients--Peter Kemp--has been doing. I have suggested to him before that‎ he might find some people to help him at the AMA. I don't know if he did get in touch, but, from the presentation below, I think you might agree that he is doing quite well on his own!

Hope you find this interesting.

Best wishes,

Steve Hawkins

VIRAS Microscopy Presentation -

Russell writes:

Hi Dr.s R and D and G,

I have caught up to all the TWIPs! Finally! Sorry this may be a long email as I have had 80+ episodes to think.

I have been listening to your show while living in Japan. I have been teaching English here since I graduated from undergrad with a degree in biochemistry.

As an undergrad, I stumbled upon the opportunity to study parasites when I attended a professor's research presentation. The information was so fascinating and novel I worked up the courage to ask, as a freshman, if there were any opportunities to work in her lab. Amazingly I was accepted and will forever be grateful for the mentorship I received as a novice. I worked on characterizing Trypanosome DNA binding proteins as therapeutic targets for the next 3 years. There I was "infected" with an interest in parasites/infectious disease.

I decided to pursue a higher degree in the communicable disease microbiology. I applied and was accepted to the University of Tokyo Graduate School of Medicine international health sciences Masters program. I'll be working on Trypanosome mitochondria complex ll as a chemotherapeutic target in the Department of Biomedical Chemistry.

The program starts April 2015 and so I have been following all the TWIX in order to keep my brain on point. I'm also reading a lot of related literature. I am now finishing Dr. Hotez's book, Forgotten People, Forgotten Diseases, which is an absolutely fantastic overview of NTDs and the public health issues from a drug development standpoint. I really hope you guys can have him on the show again! His journal PLOS NTDs is fantastic as well and he regularly writes interesting public health review pieces on various topics.

You guys have mentioned the Meguro Parasitological Museum in Tokyo, the only parasite museum in the world. I have been twice and its a great place. It's free and they have great visual exhibits like phylogenetic trees and many many preserved samples (while most text is in Japanese).

I was amazed to learn more about the huge impact Japanese researchers have had and continue to have in the field of parasitism and related fields.

Finally I must admit, I too was starting to lose interest in TWIP recently but the addition of Dr. Griffin has really reenergized the broadcast. Dr. Griffin's expertise really brings out new expert participation from Dr. Despommier as well. (Whereas anecdotes/ life cycles were starting to be repeated a lot.) Maybe I felt I understood the life cycles and characterization of the main parasites well enough therefore I was ready for more clinical experience to combine with them.

Also a question, I missed some of the first TWIM and TWIV shows. Is there an easier way to get these earlier shows than going through the TWIV website and downloading from each episode page?

Please continue to get knowledgeable guests and hosts on!
Thanks so much for your efforts,


ps I wanted to add I'm an mid-twenties American and thus I appreciate the punny banter on this and all of the other TWIX podcasts. Even when Dickson tries to stump Vincent with pop culture trivia that seems to go well over my head....

Robin writes:

TWiP 81 letters

Allan writes:

Dear Vincent & Dickson… and Daniel,

I always enjoy listening to TWIP here in Kona, Hawaii.

Our weather today is 79ºF and clear but we have just experienced a record 25-year overnight low of 54ºF,
(FREEZING, as few of us have either a heater or air conditioner in our home or office, one wears their hoody and socks to bed and work this time a year.)
I know… we’re pitifully wimpy.

I AM intrigued by your proposed inclusion of a medical case study….as long as it does not diminish your famous narrative diversions and rabbit trails.

My clinical training and work was in and exclusively for, practice in areas of the world most challenged by access to health care, setting up and strengthening local Primary Health Care. So my diagnostic thought process went as follows.

As diagnostic tests are always at a premium if available at all in these settings, the medical history and exam became especially important as was the clinical gestalt of elder medical practitioners. The left flank pain initially made one think UTI, but when ruled out, the intermediate abdominal pain and finding of a liver “cyst”, next made one think of an amebic liver abscess and a round of tinidazole (which also does NOT go well with alcohol).

As your stated tests results indicated a more fluid filled cyst than an amebic abscess, I would have last started considering Echinococcus or hydatid disease. She had the opportunity of infection, but it should have been confirmed by the ELISA. However some 10-20% of cases are false negative. I didn’t recall what the findings were for the kidney or spleen, which are more left flank. Still a few months of albendazole and or mebendazole every two weeks might both bring symptomatic relief and narrow the diagnosis. But I may still be missing something.

I appreciate you highlighting symbiotic infections that need multiple species to cause pathology, when the presence of just one may often be benign. I think this understanding illuminates a number of conditions.

Keep up the great work.


Allan Robbins, DIH, MPH
University of the Nations
Global Health Training
Kailua-Kona, HI

Daniel writes:

Cystic echinococcosis.

Dr. DJGuerra

Peter writes:

Hi TWiP team.

Here are my thoughts on the case study posed by Daniel Griffin in TWiP #80

The description of the large fluid filled cyst in the liver matches cystic echinococcosis. The patient history indicates high risk for cystic echinococcosis and I was unable to find any other plausible causes for the cyst.

IGG elisa for Echinococcus is negative but that is not conclusive.

Echinococcosis is progressive and in untreated cases it has a high mortality rate. Given that her history indicates high risk for cystic echinococcosis in terms of risk/benefit, it would I think be advisable to treat the patient for that.

A search for Hydatid Cyst Treatment came up with:

Role of Albendazole in the Management of Hydatid Cyst Liver

Hydatid Cysts of the Liver - Diagnosis, Complications and Treatment

Surgical treatment of liver hydatid cysts

Echinococcosis Hydatid Cyst Treatment & Management

A suitable treatment would be to give albendazole for several weeks, followed by puncture of the cyst under ultrasonographic guidance and aspiration of some cyst fluid for examination by light microscope. The microscope examination is to observe for the presence of viable protoscolices. If they are present, echinococcosis is confirmed and the cyst is aspirated completely.

"At this point, exclude possible connections of the cyst with the biliary tree by means of injection of contrast medium in the cavity. If no connections are evident, a scolecoidal agent, usually hyper-tonic sodium chloride solution or ethanol, is injected and left for a variable period (usually 5-30 min) and then re-aspirated. The destruction of protoscolices can be observed in fluid sample aspirated after the injection of a scolecoidal agent. This sequence is termed PAIR (puncture, aspiration, injection, re-aspiration). As happens with drug therapy, positive responses include both a decrease in cyst size and a progressive change in echo pattern (generally solidification) "

Once the risks of anaphylactic shock and secondary cyst formation been reduced (eliminated?) by the use of albendazole and scolecoidal agents, the large size and location of the cyst would probably warrant surgical removal.

As a precaution albendazole is recommended be continued for 2 months postoperatively.

I have read that some inoperable cysts are left in place. What are the advantages of surgery to remove the dead cyst? Would there be more risk of complications from surgical removal or leaving the dead cyst was left in situ (I presume that in time the dead cyst would become calcified)?

Rebekah writes:

Dear TWIP Doctors,

I have been wanting to write again for sometime, but the recent new design of the podcast really gave me the motivation. I was already happy to see the new episode, since TWIP is my favorite of the TWIX series, but the explanation of the new design really got me excited. I know I will not know all the answers, since I see very few parasites working in a small hospital in Michigan, the question really got me searching and thus learning more than I would on my own.

Before I reveal my answer to the case study I would like to share a story of my own. This was a specimen submitted on Halloween night 2014 (more like Saturday morning). A woman was concerned that she had passed a large worm in her stool, so she came into our ER with a jar of stool. The ER staff brought me the jar. My thought was that I would sort through it and try to pick out the worm or any possible proglottids that might be present. I would then clean it off to give to the pathologist for review on Monday. As I was sorting through the specimen I noticed that there was a large ribbon-like object in the specimen, so I transferredsome of it to a Petri dish and started to clean it off with some saline to reveal...PAPER TOWEL! Upon further investigation I came to realize this specimen was not stool. As a person who has seen and worked with MANY stool samples, my expert opinion is that this was strained beef stew (or equivalent, as I saw a cubed potato and a piece of parsley) with strips of paper towel mixed into it. After that, I had a very interesting conversation with the ER Physician and the ER staff sent me another specimen which was a Tapeworm they made out of paper for me, so we all had a good laugh. I am sure Dr. Despommier and Dr.Griffin have similar stories of this kind of behavior. I thought you would get a kick out of it.

Now for my answer to the case study, after much searching I still believe this is an infection with Echinococcus. I was a bit thrown because of the serological test being negative but after looking in to it further I saw that the sensitivity of the test was around 80%, so it is very possible that a false negative could have been the reason for this. I also read that the liver is the most common organ involved and that most symptomatic cysts are larger than 5cm, so it makes sense that her cyst, being smaller, would not be causing symptoms. I also read that imaging studies may not be conclusive if daughter cysts and hydatid sand are not present. I don't remember mention of these things, so I thought they likely were not present. For all of these reasons I believe the diagnosis of Echinococcus is correct. Even if I am wrong I had a lot of fun trying to work this case out! Thank you so much for this wonderful podcast.

Rebekah MLS (ASCP)
Pennock Health Services
Hastings MI

Damon writes:


You guys are great! I have listened since the beginning and enjoy all the information you provide. It has only been a mere 32 years or so since my last biology class (high school) and I'm surprised at how much basic information I have retained. Anyway, I listened to TWiP 80 today (14 Jan) and I think I know the parasite that the woman from Bangladesh carried around with her. I really perked up when I heard that she helped her father with his sheep for about three months while visiting Bangladesh. Then I reviewed TWiP 7: Tapeworms are fantastic!, and decided that she had gotten dog tapeworm(s) from her father's sheep dogs. I can only assume that this parasite can lay dormant for years (a little over three years in this case) before becoming active. I am assuming that in the dormant stage there would be no indication of the parasite's presence using the various detection methods. Were the lab results the same in May as they had been in January? Do physicians prescribe "anti-worm" drugs without a definitive diagnosis? If so, then I suppose one could prescribe the most effective drug with the least probability of bad side effects. Would it be unethical to treat for a disease in which the patient has no symptoms? Oh, and the lower abdomen pain… unrelated to the parasite?

Thank you so much for the podcast!


Justin writes:

Since I used to work in a clinical animal laboratory doing hematology and urinalysis (VCA Antech) I'd say this still sounds like it could be a(n) helminth (although maybe I should stop presuming all developing" areas have "worm" issues....) so maybe treat with a broad spectrum vermicide such as Benzimidazoles... I guess if you do the biopsy you might also release eggs/larvae of whatever it is so that sounds bad.

I have no idea which kind of helminth but I remember many of them escaped parasitology and serology a lot so many were found by GW staining or wet mounts; even found tapeworm eggs once in a urinalysis because the infestation was that bad for the dog and/or just contaminated (I found no bacteria so I doubted the contamination).

Robin writes:

In CE, surgery remains the primary treatment and the only hope for complete cure.
Better forms of chemotherapy and newer methods, such as the puncture, aspiration, injection, and reaspiration (PAIR) technique are now available but need to be tested.
• Chemotherapy in CE
◦ Indications: Chemotherapy is indicated in patients with primary liver or lung cysts that are inoperable (because of location or medical condition), patients with cysts in 2 or more organs, and peritoneal cysts.
◦ Contraindications: Early pregnancy, bone marrow suppression, chronic hepatic disease, large cysts with the risk of rupture, and inactive or calcified cysts are contraindications. A relative contraindication is bone cysts because of the significantly decreased response.
◦ Chemotherapeutic agents: Two benzimidazoles are used, albendazole and mebendazole. Albendazole is administered in several 1-month oral doses (10-15 mg/kg/d) separated by 14-day intervals. New data for continuous treatment are emerging from China. The optimal period of treatment ranges from 3-6 months, with no further increase in the incidence of adverse effects if this period is prolonged. Mebendazole is also administered for 3-6 months orally in dosages of 40-50 mg/kg/d. Limited data are available on the weekly use of praziquantel, an isoquinoline derivative, at a dose of 40 mg/kg/wk, especially in cases in which intraoperative spillage has occurred. Albendazole has been found ineffective in the treatment of primary liver cysts in patients who are surgical candidates.[5]
◦ Monitoring: Monitor patients for adverse effects of agents every 2 weeks with a CBC count and liver enzyme evaluation for the first 3 months and then every 4 weeks. Monitoring albendazole and mebendazole serum levels is desirable, but few laboratories are capable of performing this measurement. Imaging studies are required for follow-up on the morphologic status of the cyst.
◦ Outcome from medical treatment of CE: Response rates in 1000 treated patients showed that 30% had cyst disappearance (cure), 30-50% had a decrease in the size of the cyst (improvement), and 20-40% had no changes. Also, younger adults responded better than older adults.
◦ Contraindications: Because chemotherapy is the only treatment in certain cases, contraindications are limited to early pregnancy and severe leukopenia. Chemotherapeutic agents and patient monitoring are the same as with CE, but the length of treatment is different.
◦ Outcome: A significant increase in 10-year survival rates exists in patients receiving chemotherapy compared to patients who are not (85-90% vs 10%, respectively).
• PAIR in CE: The Puncture Aspiration Injection Reaspiration (PAIR) technique is performed using either ultrasound or CT guidance, involves aspiration of the cyst contents via a special cannula, followed by injection of a scolicidal agent for at least 15 minutes, and then reaspiration of the cystic contents. This is repeated until the return is clear. The cyst is then filled with isotonic sodium chloride solution. Perioperative treatment with a benzimidazole is mandatory (4 d prior to the procedure and 1-3 mo after).
◦ The PAIR technique can be performed on liver, bone, and kidney cysts but should not be performed on lung and brain cysts. The cysts should be larger than 5 cm in diameter and type I or II according to the Gharbi ultrasound classification of liver cysts (ie, type I is purely cystic; type II is purely cystic plus hydatid sand; type III has the membrane undulating in the cystic cavity; and type IV is the peripheral or diffuse distribution of coarse echoes in a complex and heterogeneous mass). PAIR can be performed on type III cysts as long as it is not a honeycomb cyst.
◦ Indications: Inoperable patients; patients refusing surgery; patients with multiple cysts in segment I, II, and III of the liver; and relapse after surgery or chemotherapy are indications for the PAIR technique.
◦ Contraindications: Early pregnancy, lung cysts, inaccessible cysts, superficially located cysts (risk of spillage), type II honeycomb cysts, type IV cysts, and cysts communicating with the biliary tree (risk of sclerosing cholangitis from the scolecoidal agent) are contraindications for the PAIR technique.
◦ Outcome: The reduced cost and shorter hospital stay associated with PAIR compared to surgery make it desirable. The risk of spillage and anaphylaxis is considerable, especially in superficially located cysts, and transhepatic puncture is recommended. Sclerosing cholangitis (chemical) and biliary fistulas are other risks. Experience is still limited, but early reports are supportive of this technique if the indications are followed.

The indications and type of surgery are different for CE and AE.

▪ Cystic echinococcosis
▪ Indications: Large liver cysts with multiple daughter cysts; superficially located single liver cysts that may rupture (traumatically or spontaneously); liver cysts with biliary tree communication or pressure effects on vital organs or structures; infected cysts; and cysts in lungs, brain, kidneys, eyes, bones, and all other organs are indications for surgery.
▪ Contraindications: General contraindications to surgical procedures (eg, extremes of age, pregnancy, severe preexisting medical conditions); multiple cysts in multiple organs; cysts that are difficult to access; dead cysts; calcified cysts; and very small cysts are contraindications.
▪ Choice of surgical technique: Radical surgery (total pericystectomy or partial affected organ resection, if possible), conservative surgery (open cystectomy), or simple tube drainage of infected and communicating cysts are choices for surgical technique. The more radical the procedure, the lower the risk of relapses but the higher the risk of complications. Patient care must be individualized accordingly.
▪ Description of surgical procedure
▪ The basic steps of the procedure are eradication of the parasite by mechanical removal, sterilization of the cyst cavity by injection of a scolicidal agent, and protection of the surrounding tissues and cavities.
▪ Scolicidal agents include formalin, hydrogen peroxide, hypertonic saline, chlorhexidine, absolute alcohol, and cetrimide. A variety of complications have been described with all scolicidal agents, but in the authors' experience, 0.5% cetrimide solution provides the best protection with the least complications. Other scolicidal agents are 70-95% ethanol and 15-20% hypertonic saline solutions. A report by Ochieng'-Mitula and Burt in 1996 on the injection of ivermectin in the hydatid cysts of infected gerbils revealed severely damaged cysts with no viable protoscoleces.[6] Further evaluation of this scolicidal agent is needed.
▪ At surgery, the exact location of the cyst is identified and correlated with the radiologic findings. The surrounding tissues are protected by covering them with cetrimide-soaked pads. The cyst is then evacuated using a strong suction device, and cetrimide is injected into the cavity. This procedure is repeated until the return is completely clear. Cetrimide is instilled and allowed to sit for 10 minutes, after which it is evacuated, and the cavity is irrigated with isotonic sodium chloride solution. This ensures both mechanical and chemical evacuation and destruction of all cyst contents. During this process, care is taken to ensure no spillage occurs to prevent seeding and secondary infestation.
▪ The cavity is then filled with isotonic sodium chloride solution and closed. Rarely, omentum is needed to fill the cavity. The cyst fluid is inspected for bile staining at the end of the evacuation and irrigation process. The inside of the cyst is inspected, and any bile duct communication is sutured. In case of infected cysts with biliary communication, closed suction drainage is required. Regardless of whether an open or laparoscopic approach is chosen, these basic principles must be followed in order to ensure the safety of the procedure.
▪ Medical requirements: The medical staff at the treating center should have experience with treating CE. Concomitant treatment with benzimidazoles (albendazole or mebendazole) has been reported to reduce the risk of secondary echinococcosis. Treatment is started 4 days preoperatively and lasts for 1 month.

Christian writes:

Dear Professors Racaniello and Despommier,

I want to draw both your attentions to an exciting new resource for researchers studying parasitic worms! WormBase-Parasite is a new public database with genome data for more than 80 helminth species. Below are links to the press release from the Wellcome Trust Sanger Institute and to WormBase-Parasite itself.

Kind regards,

PhD Student

Parasite Genomics
Wellcome Trust Sanger Institute
Wellcome Trust Genome Campus
Hinxton, UK

Wink writes:

Stacy M. Holzbauer, William A. Agger, Rebecca L. Hall, Gary M. Johnson, David Schmitt, Ann Garvey, Henry S. Bishop, Hilda Rivera, Marcos E. de Almeida, Dolores Hill, Bert E. Stromberg, Ruth Lynfield, and Kirk E. Smith. Outbreak of Trichinella spiralis Infections Associated With a Wild Boar Hunted at a Game Farm in Iowa. Clin Infect Dis. (2014) 59 (12): 1750-1756 first published online September 11, 2014 doi:10.1093/cid/ciu713

We investigated a trichinellosis outbreak associated with wild boar consumption. The index patient sought healthcare multiple times before being diagnosed. Targeted education of hunters and consumers handling wild game or free-range pork, owners of game farms, and clinicians is warranted.


Robert writes:

Sorry for replying to an old episode, but I thought you might want the following information if you haven't heard it from anyone else yet.

Fiona who wrote in referring to "rope worms" said she was using MMS enemas to treat them.

Here is some added information that MMS (miracle mineral supplement) refers to a handfull of different chlorine dioxide evolving solutions, and the usual dosing being increasing doses until the side effects require backing down (oraly until you can no longer avoid emesis, or as enemas until diarrhea). The "rope worms" seem to be sloughed off intestinal mucosa.

MMS has been linked to deaths both due to side effects and delay or refusal of proven treatments for various diseases. While the eponymous miracle mineral solution has been banned in various markets people continue to buy the chemicals that can be used to generate chlorine dioxide and dose themselves in the hope of dealing with their various medical problems. I hope Fiona is doing better, and no longer using chlorine bleach internally.

Robert S.
ps: thank you for your ongoing efforts to produce the "this week in" podcasts.

Erik writes:

Hello Dickson and Vincent!
I just came across this video on youtube:

It shows the extraction of a bizarrely long worm from a praying mantis. It's hard to believe that the mantis was still alive with that thing in it. At first this was just a cringe-worthy video that I wanted to share with TWiP as maybe a listener pick of the week, but then I read a bit about the parasite, which turns out to be a nematode called a horsehair worm. It's a very interesting parasite, and one of those that alters host behavior (which has been discussed several times on TWiP). It's a parasite of arthropods and infects beetles, cockroaches, grasshoppers, and even some crustaceans.

I haven't delved very deeply into the life-cycle, but I read that the adults are free-living in freshwater but somehow their eggs find their way to their arthropod hosts and, eventually, infection with have an effect on the host's brain which drives it to seek water and drown, thus releasing the adult form of the worm.

These fascinating "mind-altering" parasites have been discussed on TWiP in the past, but I think it would be fun to have an episode dedicated to a vast array of these bizarre and, in some cases grizzly, examples of how parasites affect their host's behavior. Another example, which I think has been mentioned in passing on a previous episode, is Cordyceps (

Anyways, I'd like to say that I greatly enjoy TWiP and all of the other TWiX podcasts (particularly TWiV, since viruses are my main area of interest) and I am always eager for the next episodes to arrive. I admit, I'm one of many who would love a more frequent TWiP schedule, but I understand that you're both very busy, so I suppose monthly-ish will be enough to give me my parasite fix.

Kindest regards,

Jeffrey writes:

Hey Twippers,

I am really excited about the new format and the addition of Daniel to the team. It seems like he will add a really interesting perspective to the talk - and maybe some great tangential stories (which I love, by the way).

Keep on TWIPping!

Seattle, WA
Mostly Cloudy
46°F, 8°C
60% chance of precipitation
Humidity: 90%
Wind: 0km/h

TWiP 80 letters

Jessica writes:

Hello Dr Racaniello and Despommier,

I recently saw an article about the paper linked below on Science Daily and thought it might be worth a discussion on TWIP. It is about the possibility of bed bugs being a vector for T. cruzi. I would love to hear your opinion on what implications these results could have on the transmission of Chagas disease.

Thank you for TWIP, TWIV, and TWIM and all the hours you put educating the public.

Keep up the amazing podcasts,


Peter writes:

Dear TWiP team

I remember sparganosis from TWiP#8: Frog legs and parasite tales so was interested to read of a case in the UK:

The patient was from China so presumably contracted the parasite there.
The remains of the worm were genetically sequenced and identified as Spirometra erinaceieuropaei:

The species name erinaceieuropaei suggests that it was first identified from the European hedgehog which seems strange for a parasite said to originate from the far east.


Kevin writes:

Thought you folks might like to hear about this!

"A nematode worm's brain has been mapped, simulated in software & put into a lego robot which now *acts like a worm*"

Andrea writes:

Howdy Dickson and Vincent!

I am glad for the new TWIP podcast.

I am sure you saw this story:

When I read it I thought of the two you. I suffered from migraines for years, I'm so glad that it wasn't a tapeworm!

It is rainy and 50F here in Seattle just the way I love it!

I too am sad about the Car Talk brother's, Tommy, passing. He was such a joy!

Take care!

Wink writes:

Loved the last TWIP, and all the rest. I had read long ago that vivax relapses occur with a periodicity of 3 months; not necessarily every 3 months, but multiples of 3 months. Is this true?

Atlanta, GA

Øystein writes:

Dear Vincent Racaniello and Dick Despommier,

I just read an intriguing article on the parasite Cryptosporidium, that concludes:
"The observation of extracellular developmental stages in this study further supports suggestions that classification of Cryptosporidium as an obligate intracellular apicomplexan may require revision"

Article attached (open access).

The story of this parasite is unfolding before our eyes. Maybe you would like to revisit this parasite again on your show. Cryptosporidium research is generating more interest than before because of the new evidence from the Global Enteric Multicenter Study (GEMS) that Cryptosporidium ranks as the second most important cause of severe childhood dirrhoea after rotavirus.

If the parasite can replicate in biofilms growing on the inside of our water pipes we might have a bigger problem than we realized.

I still follow all your TWIX family shows with great pleasure, and have been following you since the very beginning. Thank you again for your inspiring podcasts.

All the best,


Consultant Clinical Microbiologist
Vestfold Hospital Trust, Tønsberg, Norway
Currently in : Black Lion Hospital, Addis Ababa, Ethiopia

Sharmbey writes:

Hey, my name is Sharmbey (SB) in College Park, MD. I started listening to TWIP in August 2014 in order. As I type I'm on #52. It's been extremely entertaining hearing you guys talk so much mess to each other, yet so humble every time. Perfect. I'm not a student or working in any type of science field but I love all science. Dr.D, I've been thinking of "tall buildings to grow crops" for years before I knew other people actually started it. Finding you was mind-blowing with your fancy "vertical farm". :-) If you guys read this it will be awesome to hear my name by the time I catch up to the episode. I can clearly see you guys have plenty of content so I wont ask "dont stop". In episode #52, a listener tells of a great grandparent sick with malaria in the past. That reminded me of the book As I Lay Dying where a dying mother or grandmother rode in a wagon on a long trip. Maybe they had malaria in the book. Just a random thought. Anyway, keep up the great work. Oh yeah. You don't need me to tell you, but I want to say "forget" that guy or anybody who comments on your style. Tell as many stories, related or unrelated, as you like. Who's names are on the title?? Like I said, you guys are the perfect blend of a wealth of knowledge and some comedy. Vince bashes Dickson, while Dickson is humble about it. Then Dickson is like more rough and gruff and more crude, in a good way, while Vince tries to defend the subject at hand. Great stuff. I probably won't write again so I'm getting it all out now. I'm a delivery driver with La Prima Catering and I go to Walter Reed, NIH, NASA, NOAA, UMD very often and its so cool hearing what's going on in these places. I think I'm done. SB out.


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