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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

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.
http://www.ncbi.nlm.nih.gov/pubmed/19915815

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
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3178923/

Hydatid Cysts of the Liver - Diagnosis, Complications and Treatment
http://www.intechopen.com/books/abdominal-surgery/hydatid-cysts-of-the-liver-diagnosis-complications-and-treatment

Surgical treatment of liver hydatid cysts
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2131364/

Echinococcosis Hydatid Cyst Treatment & Management
http://emedicine.medscape.com/article/216432-treatment#a1129

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)
Microbiology
Pennock Health Services
Hastings MI

Damon writes:

Doctors,

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!

Damon

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.

https://www.sanger.ac.uk/about/press/2014/141128.html
http://parasite.wormbase.org/index.html

Kind regards,
Christian

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.

Wink
Atlanta

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:

https://www.youtube.com/watch?v=TO8A5aGw_jw

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 (https://www.youtube.com/watch?v=XuKjBIBBAL8).

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,
Erik

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!

Jeff
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.

http://www.ajtmh.org/content/early/2014/11/13/ajtmh.14-0483.full.pdf+html?sid=a538658b-bd6d-4df8-b0f3-6eb61f7a09f0

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

Keep up the amazing podcasts,

Jess
Chemist

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:

http://www.newscientist.com/article/dn26597-watch-a-tapeworm-squirm-through-a-living-mans-brain.html

The patient was from China so presumably contracted the parasite there.
The remains of the worm were genetically sequenced and identified as Spirometra erinaceieuropaei:
http://genomebiology.com/2014/15/11/510/abstract

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.

Regards

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*" http://t.co/8louz6qp2w
(via https://twitter.com/s8mb/status/534480594970083328?s=03)

Andrea writes:

Howdy Dickson and Vincent!

I am glad for the new TWIP podcast.

I am sure you saw this story:

http://www.latimes.com/science/sciencenow/la-sci-sn-headache-brain-tapeworm-20141121-story.html

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?

Wink
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,

Øystein

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.

 

TWiP 79 letters

Jesse writes:

Doctors TWiP,

I came across this paper and thought it sounded interesting for a discussion on TWiP:

Colonisation resistance in the sand fly gut: Leishmania protects Lutzomyia longipalpis from bacterial infection
http://www.parasitesandvectors.com/content/7/1/329

Press release for it: www.sciencedaily.com/releases/2014/07/140723110659.htm

Thanks for your good work,
Jesse

Jesper writes:

Professors,

Thank you for your continued effort in sharing your knowledge and scientific enthusiasm. It is always a pleasure to listen to the TWIx-shows and I have learned lot from them all.

I just ran into an interesting article on how T Gondi may change the behaviour of its human host. You might find it worth reading. http://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/.

On a side note, it seems TWIP does not have facebook presence. Unless that depends on my poor searching ability you may want to consider rectifying that.

Best regards,

--Jesper

Simon writes:

Dear Professors,

Firstly I would like to share with you the attached photograph. I was in London a few weeks ago waiting to meet a friend in Cavendish Square, which is right next door to the Royal Society of Medicine. In order to kill time I was walking around the square and I noticed a blue plaque on a nearby house (they are quite common in London denoting places of historic interest). As soon as I saw it, I knew I had to take a picture to send in to you, particularly as I have recently been listing to the series of episodes on malaria from the early days of Twip.

Secondly, in a free moment I was browsing the PLOS website the other day (I think Neglected Tropical Diseases has to be my favorite journal name), and came across the following paper: Diverse Host-Seeking Behaviors of Skin-Penetrating Nematodes (http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1004305).

Interestingly, the data seem to suggest the key role of olfaction in nematode host identification, and this reminded me of your discussion on TWiP 78 of odor detection by mosquitos. The fact that both mosquitos (as carriers of malaria), and these skin-penetrating nematodes have evolved sensitive olfactory responses led me to wonder if this is a very common host detection strategy among free-living/moving parasites? Do you know of other examples?

Thank you in advance for your comments.

Simon

Anne Marie writes:

I went to Belize this summer and noticed the attached sign at a roadside tamale place. I thought you two might appreciate seeing it. I don't know if you guys speak Spanish so I thought I'd translate it as best I can:

"For a community free of Leishmaniasis

These are diseases caused by a parasite called Leishmania that transmit to humans through sand fly bites.
Wear a thick, long-sleeved shirt, thick pants, a hat with a wide brim and work boots in the forest or jungle.
Keep you house clean, ordered and free of trash and weeds.
Keep animals (including dogs and cats) out of the house, in clean, secure places.
Use fine mesh mosquito nets daily. Cover yourself after dark and cover children after 5 pm.
Go to the nearest Health Service, TREATMENT IS FREE."

Also: my dad got ehrlichiosis while orienteering in Maryland. He felt cruddy for a long time but had no lingering ill effects. (He's also been bitten by a rattlesnake!)

My best,
Anne Marie

Abe writes:

Hi,

I just started binge-listening to all the episodes of TWIV and TWIP from the beginning. These are great! As an interested scientist in a completely different field, I wanted to ask:

TWiP: Are there any examples yet of Archaea acting as parasites to hosts in the other kingdoms? If not, are there specific biochemical reasons why it would be impossible?

Yours,
Abe

Chelsea writes:

Hi Vincent and Dickson,

I hope this e-mail finds you both well! I am a big TWiP fan - the podcast is fantastic for getting good science across in an entertaining way. I'm even assigning several of your episodes to students in my "Ecology of Human Parasites" course at UMich!

I'm attaching info on an opportunity for early career scientists to present their work on "ecosystems within organisms" - any aspect of ecology and evolution of the microbiome. This Early Career Scientists Symposium will be held at UMich in late March. Many of your listeners may be excellent candidates, so I would be very grateful if you could mention the call for nominations on your next episode.

Keep up the great work!

Christophe writes:

Hi Guys,

I saw this article and thought it would interest Dickson (assuming he hasn't seen it already)

http://arstechnica.com/science/2014/11/mosquitos-evolved-to-specialize-on-human-prey/

Stephen writes:

Dear Professors Racaniello and Despommier,

I have two "corrections" for you. First, in episode 2, Prof Despommier named Darwin's Bulldog as Aldous Huxley. The correct Huxley is Thomas Henry Huxley. Aldous was a much more recent philosopher and writer of fiction.

Second, in episode 17 (Entamoeba histolytica) - which I'm only half way through - polar ice melt and consequent sea level rises were mentioned. Prof Despommier's explanation for the difference in effect of melting at the north and south poles was not really right. The real difference is that the ice at the north pole is almost all floating sea ice, so it's already displacing a mass of water equivalent to the mass of the ice - thus when the ice melts, it will have no nett effect (ignoring the warming of the water which would result in some thermal expansion). The antarctic ice, however, is most sitting on top of the vast landmass that is the continent of Antarctica. So when it melts, there will be water - and plenty of it - added to the ocean system.

I came to TWiP via TWiV (which I started listening to during the height of ebola news coverage this year). Last week I also added TWiM. I'm slowly working my way through the back catalogue. All of the podcasts have me feeling vague pangs of regret at having left science after graduating. Thank you for making great shows that are accessible, entertaining and educational all at the same time.

Regards,
Stephen

TWiP 78 letters

Meliani writes:

Dear Sir,

My research is focused on the biofilms formation, Motility (swarming and swiming ) and QS in fluorescent Pseudomonas (P. aeruginosa and P. fluorescens).

In laboratory a interaction had been with insect and bacteria metaboliye EPS (so a Bacteriophile insect).
I do not know the identity of this namtode, is a parasitism interaction? or symbiosis one , to interprete my figures.
Please could you give me it name?

Hope to read you, I ask you to please accept my best wishes.

Thank you very much for Reading my message.

Best regards

Dr. Meliani

Microbial Ecology Professor researcher at the University of Mascara, Algeria

Peter writes:

Dear TWiP team
I saw this report on the BBC and thought it may be worth a mention on TWiP:

A woman was horrified to discover that her nosebleeds had been caused by a leech living in her nostril. Daniela Liverani from Glasgow started having persistent nosebleeds after a backpacking trip around South-East Asia, At first she thought her nosebleeds the result of a motorcycle accident but sought medical assistance when she noticed the nosebleed "had ridges" and had started "poking out" of her nose and wriggling.

http://www.bbc.co.uk/news/uk-scotland-29595164

Regards

Peter writes:

Dear Dickson and Vincent.

I recently finished reading Dickson's book "People, Parasites, and Plowshares'.
Looking for further information on the topics covered in the book I found this paper reviewing studies of the effects of helminth infection in reducing the rejection of transplanted tissue.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3940291/

Maybe it could be discussed on TWiP, or be a listener pick of the week.

I would also like to recommend the Coursera course Epidemics - the Dynamics of Infectious Diseases
which I am sure would interest TWiP and TWiM listeners.

Regards

TWiP 77 letters

Andy writes:

Dear Professors,

I have been following TWIP for several years. I am a software engineer and parasitology is only an avocation. As an undergraduate in the early 80's I discovered my love of history of science and ecology, although I continued the path of a software developer. As an adult I read Carl Zimmer's Parasite Rex and became totally fascinated with parasitology. Later I read The Coming Plague by Laurie Garrett. What I love about both Mr Zimmer's and Ms Garrett's writing is how they tie the science to the scientist. I look at The Coming Plague as a masterpiece in history of science with really touching stories of the scientists and their impact on the world.

I'm writing to ask you to make sure that when you talk about the science of parasitology, you keep including the stories of who figured out what and why it was important. The two of you bring a lot of experience in parasitology, microbiology, and virology and have lived the history of it--keep the stories coming!

If you haven't watched this, I recommend that you do. It's a lecture by Prof Walter Munk on his life's work in the field of oceanography. Fascinating!

http://www.uctv.tv/shows/Where-the-Swell-Begins-24248

Andy
Saint Paul, MN

P.S. I also recommend the book Krakatoa: The Day the World Exploded as a great book with history, anthropology, and science all tied together with history of science.

Mike writes:

Bobbi Pritt was a superb guest. As Vincent commented, 'now we get to hear the pronunciations of the parasites' or something along those lines which I also found helpful. I had almost given up on this podcast because it seems to lack focus and rambles a bit. Hope you are able to get more people like Bobbi on your show.
Mike in Oregon

Kyrie writes:

Hi Dixon & Vincent,

Recently I got a wonderful pug puppy from a local puppy mill store ( which I know no one should ever do but I had just lost another dog that was with me for 12 years and I walked by not a puppy trap not in a rational state) the puppy it turns out has demotic mange.

I had read about an oil from India called neem that by some mechanism blocks the reproduction if bacteria, parasites, fungus everything!

I put it on my dog and weird white things started coming off within a half hour. I dusted her off and they came back again 4 times. What is that? I also wash her twice a week with Borox and vinegar.

What do you know about neem oil and its effects on the parasitic life cycle and what can you tell me about demotic mange and their behavior ?

Anything would be helpful. The dog I bought is super cute but has many health issues so I am trying the natural path to reduce complexity.

Also a side note Vincent your are wonderful and fascinating but why so hard on your good friend Dixon?

He seems like such a sweet person sometimes I want to yell as the podcast at you leave him alone!

BTW: I listen to all the twi + x podcasts as I go to sleep every night! Best science podcasts out there. Thank you and all the wonderful people on the show for giving the lay people a little real science.

As a side note, I am a software developer that has zero to do with microbiology outside of the fact that it effects us all. Thank you for the peek into the very small universe it's really fascinating.

I am so grateful!

Thanks for everything you do,

Kyrie

Rebeka writes:

Hello Doctors,

I have just started listening to TWiP and am on episode 20 currently. I had a couple things I wanted to share and I apologize if these are things you have already covered in more recent episodes. First in the episodes regarding Giardia and Entamoeba histolytica it was stated that these are not reportable. Being a Medical Laboratory Scientist (once called Med tech) I do report these to the local health department when we recover them. I live in Michigan, so maybe the regulations are different where you are. I have attached a copy of the MDCH reportable diseases for you.

Also, when I was an undergrad I read an article about a vaccine that targeted the gut of ticks, so that when the tick took a blood meal from an animal the antibodies would be ingested as well and kill the tick. This reduces the amount of ticks in an area and the overall tick borne diseases. I did a quick search and sure enough this research is still going on! What do you think about the possibilities of a vaccine similar against say mosquitoes? Ticks take a larger blood meal, so it might not work, but it is still an interesting idea. Here is the link to the current work :http://www.parasitesandvectors.com/content/7/1/77

I absolutely love the show! I also teach Microbiology to Medical Laboratory Technicians at a community college and I am going to recommend this podcast for them to prepare for their board of certification exams.

Thank you again for the fantastic show.

Rebekah MLS (ASCP)

Erica writes:

Hi

I'm a Zoology graduate currently working in a parasitology lab and applying for molecular parasitology PhDs in Ireland.

Recently found your podcast and really enjoying listening to it in the lab.

Wanted to say thanks, I was surprised at the lack of parasitology podcasts out there and I'm glad you have it covered :)

Would enjoy it if you delved into some parasites of agricultural importance such as PPNs.

Keep it up

Regards

Erica

Alex writes:

Hi guys

Love your twip. Dickson, you mentioned in Twip 76 that H. polygyrus is the best model we have for human hookworm. You might be interested in this paper attached that we recently published which highlights how similar Nippostrongylus and Necator really are in terms of their biology and secretomes. I now think of Nippo as a better model for human hookworm infection than H. poly. Keep up the great work on the show! Thoroughly entertaining and informative.
Cheers
Alex Loukas

Professor Alex Loukas, PhD
NHMRC Principal Research Fellow
Director, Centre for Biodiscovery and Molecular Development of Therapeutics
Australian Institute of Tropical Health & Medicine
James Cook University
Cairns, Australia

Robin writes:

Dave from Fresno (that's where I live!) in your emails suggested that DVT may embolise to the brain. If it does, it would indicate an atrial septal defect or a ventricular septal defect: the emboli are too big to traverse the pulmonary capillaries.

Also aspirin and other antiplatelet agents are primarily effective against platelet thrombi, which are aggregations of platelets, like snowdrifts, at sites of rapid flow, viz. arteries. Such thrombi are friable, adherent, and less likely to detach en masse. DVT is more akin to a blood clot in a test tube.

Multiple ring forms of the malarial parasite in an erythrocyte is indicative of Plasmodium falciparum infection.

TWiP 76 letters

Daniel writes:

Dear Vincent and Dickson,

I just returned from the annual meeting of the International Society of Travel Medicine (ISTM) where I enjoyed many fantastic lectures and caught more Cutthroat Trout fly fishing the upper Snake River during one evening than I could count. I will confess to using a hopper with a bead head dropper to achieve this. I was relaxing on this beautiful Sunday morning with a cup of coffee in hand and the August 1st issue of Science. To my delight I saw that the cover had a colorized scanning micrograph of a dog roundworm (Toxocara canis). This image on the cover directed the reader to a commentary and to two research reports about how infection with parasites influences the immune system in such a way that antiviral immunity is impaired.

I am an MD trained as an infectious disease specialist and am active in the care of immigrants, travelers and indigent patients suffering from infectious diseases. At NYU School of Medicine I received excellent training in parasitic disease from a dynamic visiting professor that has served me well in China, Africa, Nepal and here in the states. My PhD is in Immunology and my early work involved defining the phenotype of human B1 cells, an innate subset of B cells. My current work is on HIV latency in hematopoeitic stem cells. These research reports were thus as they say ‘right up my alley’. The commentary is readily accessible to a broad audience and explains how the two research reports demonstrate that helminth infections induce viral exit from a latent state. The two research reports contain the expected rigor one sees in Science.

These reports seem a perfect crossing of both your areas of focus, Vincent’s expertise in virology and Dickson’s expertise in eukaryotic parasites. Schistosoma mansoni is one of the parasites involved in the first article and one even my kids know about after swimming in Lake Malawi this past winter. Trichinella is used in the second paper and is not only dear to Dickson’s heart but something we still see up in Alaska, where I worked until recently. To fully disclose my fascination with parasites, the discussion my physician friend from Alaska and I were having as we caught cutthroat trout on the Snake last week was about the two cases of acute Trichinosis that he recently managed in a married Alaska couple from eating undercooked bear meat.

I am left thinking that Dickson needs to fish the upper Snake River in Wyoming, but more importantly he might consider writing a monograph entitled not People, Parasites & Plowshares but: Parasites: When Plowshares become Swords!

Sincerely,

Daniel Griffin, MD PhD
Associate Research Scientist
Department of Biochemisty and Molecular BioPhysics
Columbia University

Francois writes:

Vincent, you’ve got French listeners, at least one!

I'm living in Montpellier (south of France) were the sun is shining.

Here two very visuals picks of the week.

You already know of the glass virus of Luke jerram, but here the malaria model
http://www.lukejerram.com/glass/gallery/malaria

And also for sheer beauty ... Giant glass flower from Jason Gamrath
http://www.demilked.com/gigantic-glass-flowers-jason-gamrath/

François

Robin writes:

Various items

Malaria prevalence
Can be so high that asymptomatic parasitaemia is the norm: it was 95+% among adults of some New Guinea tribes and over 70% among the adults in the territory of Anopheles gambiae.

French speakers
Among the reasons I am not a French speaker were Horatio Nelson and the Duke of Wellington, to neither of whom I have any affinity or allegiance. But they were among the reasons that the Raj was a British Raj, and not a French one. An important reason also why so many Indians (& Pakistanis) speak adequate if not good English, and little or no French.

Schizont pronunciation
http://www.thefreedictionary.com/_/dict.aspx?word=schizont

Single vs multiple ring forms
Multiple rings in an RBC is bad news.

Parasites are doomed
As in the answer to the question about Bob Dole in the 1996 presidential election - "Does he wear boxers or briefs?": "Depends". Those that adapt well enough may become a necessary feature, as Dr. Dickson has explained with regard to intestinal parasites and autoimmune disorders of the gut (and perhaps elsewhere). And let's not forget the bacterium that invaded an Archean to produce the great*gazillion grandparent of all of today's eukaryotes. Mitochondria are no longer parasites.

Extra membrane protein in RBC cytoplasm
One reason for it may be to prolong the life of the RBCs. Think of a tire filled with tread that can migrate to the outside as the tread on the outside is worn away. RBCs are subject to plenty of wear as they squeeze through narrow capillaries.

Movement of Homo sapiens and other hominids outside Africa Extincted by human disease
There were two (known) non-sapiens lineages outside Africa in later times that we met: neanderthals and denisovans. We may have also met floresiensis but there is no genetic evidence for commingling. Just about all other hominid species were in Africa and were exposed to the infective load found there. Moreover, we coexisted with Neanderthals for ten millennia or more.

Within our species 14 disease-free millennia after crossing the Bering land bridge into the New World and several more disease-free millennia preceding in Siberia helped to make Native Americans susceptible to smallpox and measles, thus enabling settlement of vacated territory by Europeans who brought those diseases as naturally as their ectoparasites.

Homo habilis evolved into Neanderthal
I had the impression that it was a more advanced form: Homo heidelbergensis.

Colder climate - invasive species
The hairless ape is adapted to year-round tropical weather. Anywhere else it is an invasive species: to survive elsewhere it has a cultural/technological adaptation that proceeded much faster than evolution: shelter & clothing.

Cause of migration civil war
Not necessarily. It would be doubtful whether the migration across the Bering land bridge was due to civil war. The migration of Jews out of Europe in the time of the Third Reich was not quite due to "civil" war. Or of Armenians out of their lands annexed by Turkey.

Extravasation
Coming out of a vessel (vas=vessel). Could be a tubular vessel such as for blood or lymph, but also a sac-like vessel such as for urine or bile. Malarial parasites coming out of an RBC don't quite cut the mustard.
A reminder for the upcoming podcast:
Ask parasitologist from Mayo clinic about lice & anemia.

My personal guess is that it would not be due to depletion by volume, but perhaps the adaptation of the body of some substance injected by the lice to act as a signal that causes the body to make the blood less nutritious.

And in case Dr. Dickson wants to know what she looks like:
http://instagram.com/p/XScFXyvaOy/

David writes:

Dear Vince,
Long long flight, yes.
What is a chief, but invisible, physiodynamic consequence of even short flights?
Deep vein thrombosis in lower extremities. Cuts loose as ambulating off plane. Throws embolis to lungs, even heart, brain. Pulmonary embolism is a big deal.
Prophylaxis? Wiggle your feet, ankles, calves regularly. Venous return is passive, and hydraulically driven by muscle massage of lower veins in the course of everyday activity.
Lack of activity lets blood accumulate above vein valves. Leg bent at knee, and dependent, further kinks veins. Unmoving blood begins clotting, especially in guys of a certain age. If not troubled in flight, they then walk off plane and collapse.
To prevent, extend legs, and isometrically flex and extend them even when bent. Get up and about in flight at any excuse, and for none.
Alcohol may repress clotting some. At minimally higher risk of uncontrolled bleeding, a bit of aspirin probably wouldn't hurt. Bloody Marys are nutritious.
Travel well. Wish I were there.
Dave
Fresno

Tristen writes:

Dear Vincent and Dixon,
I'm not sure if you got my email a few weeks ago since I sent it from my personal email and not through the website so I'm sending it again just in case.

I have to tell you that I'm a huge fan of TWiP and I love listening to you guys! In November 2013 I did my first medical mission trip to Nzara, South Sudan. Vincent you probably already know an interesting virology fact about Nzara- it's one of the first places Ebola virus was discovered in 1976. After the short trip I enjoyed the work so much that now I am trying to gain funding so I can leave life here and continue the work in Nzara for a couple years. I appreciate how your podcasts are both educational and entertaining at the same time. My favorite one so far is when you had Peter Hotez on talking about neglected tropical diseases.

You guys should really do an episode about chronic malaria infection in children living in sub Saharan Africa and the connection between Epstein Barr virus and the high rate of pediatric burkitts lymphoma diagnosis. People get tired of hearing about malaria, but this would be a great podcast because it combines parasitology and virology. I find it quite interesting and happen to learn about this connection when I had plasmodium malariae after returning from my trip (despite taking malarone). Thank you both for your good work and for giving me such valuable information which I can take back with me to South Sudan!

Malaria-EBV-lymphoma research:
http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.0030080

http://www.newscientist.com/article/dn12033-malaria-linked-to-child-cancer-in-africa.html#.U53aWye9KSN

Truly,
Tristen

Zephyr writes:

Hello, Doctors Vincent and Dick,

In the episode TWiP 73 (Entamoeba histolytica) I heard the following misconception:

Dick Despommier: (44:33) "Name a mammal that has nucleated red [blood] cells. Camels." (44:35)

In spite of their rather peculiar elliptical shape and other abnormal features (see below), camelid red blood cells are by no means nucleated:

"The elliptical, anucleate erythrocytes of camels have been examined for the presence of marginal bands and their constituent microtubules. Lysis of erythrocytes under microtubule-stabilizing conditions readily revealed marginal bands in at least 3 % of the cells, as observed by phase-contrast and darkfield light microscopy. Microtubules plus a marginal band-encompassing network of material are visible in lysed cell whole mounts with transmission electron microscopy. Marginal band microtubules are also evident in electron micrographs of thin-sectioned camel erythrocytes identifiable as reticuloyctes on the basis of submaximal electron density (reduced haemoglobin iron content) and presence of polysomes. The results suggest that marginal bands may be involved in morphogenesis of camel erythrocytes but are not required for maintenance of their ellipticity after cells are fully differentiated."

“Among the mammals, members of the family Camelidae (camels, vicunas, guanacos, llamas, alpacas) are unique in that their erythrocytes, though anucleate, are elliptical (Andrew, 1965). The question thus arises as to whether MBs play a role in cell shape generation and/or maintenance in these species.”

— Cohen WD and Terwilliger NB. "Marginal bands in camel erythrocytes." J Cell Sci (1979) vol. 36 pp. 97-107
Open access: http://jcs.biologists.org/content/36/1/97.long
http://www.ncbi.nlm.nih.gov/pubmed/457820

More pics of camelid red blood cells, this time from one of the camel’s close relatives, llamas:

• Azwai SM et al. "Morphological characteristics of blood cells in clinically normal adult llamas (Lama glama)." Veterinarski arhiv (2007) vol. 77 (1) pp. 69-79
Open access: http://hrcak.srce.hr/file/39723
http://hrcak.srce.hr/index.php?show=clanak&id_clanak_jezik=39723
http://www.vef.unizg.hr/vetarhiv/papers/2007-77-1-9.pdf

It seems to be a rather widespread confusion in educational circles, I also succumbed to this false notion during my undergraduate years. Then one day I decided to look up the possible advantages that could offer the presence of nucleated cells in camels. My wild guess was that perhaps those red blood cells could work in tandem with their also rather peculiar subset of homodimeric immunoglobulins G to keep at bay particularly harmful parasites that might have infested those animals at some point. It turned out that it had nothing to do, and the characteristic elliptical shape of their red blood cells are thought to be an adaptation to extreme dehydration and rapid rehydration, and possibly to increase the efficiency for carrying oxygen at high altitude:

In camels (Cohen and Terwilliger):

“The occurrence of MBs in camel erythrocytes is possibly correlated with ontogeny of distinctive physiological properties. Camels are adapted to survive extreme dehydration and rapid rehydration. Their erythrocytes can withstand considerable osmotic stress, responding in a manner more similar to the elliptical, nucleated erythrocytes of non-mammalian vertebrates than to the biconcave diskoidal cells typical of other mammals (Ponder, 1942; Trotter, 1956). Camel erythrocytes are highly resistant to hypotonic haemolysis (Perk, 1963; Yagil, Sod-Moriah & Meyerstein, 1974), exhibit a low rate of water transport (Naccache & Sha'afi, 1974), and are also relatively stable under hypertonic conditions, in which crenation was not observed (Yagil et al. 1974). In addition, very young camels (6 months or less) apparently possess 2 populations of erythrocytes with respect to osmotic resistance: one population with adult-type response, the other with still greater haemolytic resistance (Pe
rk, 1966). Direct studies of the possible correlation between occurrence of MBs and osmotic resistance in camel erythrocytes would therefore appear to have potential value for understanding MB and erythrocyte function.”

In llamas (Azwai et al.):

“Llamoid erythrocytes were small (7.32 ± 0.95 × 3.9 ± 0.52 μm), elliptical, flat and their counts obtained in the present study (10.3 to 15.0 ×106/ μL) were higher than those in other domestic animals (FELDMAN et al., 2000). The flat shape and the presence of the few folded erythrocytes were attributed to the low thickness to diameter ratio of llama red blood cells (VAN HOUTEN et al., 1992). The small volume resulted in a high concentration of erythrocytes for any given PCV. The high MCHC of llama (38.6 to 48.0 g/dL) in comparison with those in other species might be due to the flat nature of the erythrocytes, which allowed more space for haemoglobin molecules to increase their efficiency for carrying oxygen at high altitude (HAWKEY, 1975). It was evident that llama bone marrow, unlike other ruminants except dromedary camels (MOORE, 2000), was normally releasing immature erythrocytes, including polychromatic rubricytes, metarubricytes (0.8%) and reticulocytes (0.4%) i
nto circulation.”

“In general, the unique elliptical, flat camelid erythrocytes facilitate their movement in capillaries at times of dehydration in arid areas, (SMITH et al., 1979; SMITH et al., 1980) minimizing the likelihood of sludging.”

Sincerely,

Zephyr

Curtis writes:

Maybe you've already done a segment on Toxocara and it's hidden under a clever title, but if you haven't done one so far, would you consider doing a podcast?

I just discovered TWIP and what a treasure trove it is! Thanks for all your efforts.

Best,

Curtis

John writes:

Dickson sometimes mentions how crows eat roadkill. They eat the contents of the animal's intestines, rather than its parasite-infested organs. I witnessed a crow eating a California Ground Squirrel and Dickson's explanation helped me understand that the crow was not playing with its food, but rather being picky.

I shot a video, which may be too graphic for some listeners:

https://www.flickr.com/photos/31715949@N00/9653686629>

Technically my crow is a raven, which is a fancy name for a crow with a big beak.

 

TWiP 75 letters

David writes (re lice and iron):

All I remember that I know is that one time I let my cat endure a heavy flea infestation for an unconscionably long time. I redeemed myself, if at all, by the knowledge that I slept with her a lot, and so endured a share myself (but I'm extraordinarily thick skinned, so it wasn't so bad, and I didn't get plague).

Anyway, the situation's gravity was brought home to me when I discovered that she was significantly anemic. Clearing the fleas and maintaining her freedom from parasites of any kind found the anemia gone and blood restored to a normal hct, hgb after a few months. In other words, the insects consumed a significant quantity of blood.

Lice aren't fleas of course, and people are bigger than cats, so I don't know if the lady who corresponded with you about her and her daughters' lice and her longstanding iron supplementation will have her case at all illuminated by my anecdote, but I do know that fleas can drain a consequential amount of blood from some of us.

What do you think?

Yours,
Dave
Fresno

TWiP 73 letters

Robin writes:

Liquids

Liquids are capable of forming a gas-liquid interface: maintenance of the surface requires adequate pressure in the gas. Adequate in this instance means a gas pressure greater than the vaporisation pressure in the liquid. The gas pressure is a sort of cork preventing the liquid from boiling away.

The vaporisation pressure increases with the temperature. When the vaporisation pressure equals the gas pressure, the liquid starts to boil. In the absence of any gas pressure, a liquid-gas interface cannot be maintained: that is why astronauts' blood would boil if they are exposed to the vacuum of space.

Also in the vacuum of space, when a solid is heated to its melting point it will convert directly into gas, the process being known as sublimation. In earth's atmosphere if the solid's vaporisation pressure at its melting point is greater than the atmospheric pressure, it will transit directly from solid to gas, as in the case of carbon dioxide.

Toads vs. frogs:

While toads are not a taxonomic group, use of the word "toad" implies the exclusion of or differentiation from frogs.

Toads tend to be more terrestrially adapted, with a dry skin, no cutaneous respiration, no webbing between the toes, and spending most of their adult lives on terra firma.

Reptiles are a paraphyletic group:

http://en.m.wikipedia.org/wiki/Paraphyly

“a group is said to be paraphyletic if it consists of all the descendants of the last common ancestor of the group's members minus a small number of monophyletic groups of descendants, typically just one or two such groups. Such a group is said to be paraphyletic with respect to the excluded groups. For example, the group of reptiles, as traditionally defined, is paraphyletic with respect to the mammals and birds: it contains the last common ancestor of the reptiles—including the extant reptiles as well as the extinct mammal-like reptiles—along with all descendants of that ancestor except for mammals and birds. ”

Dinosaurs are tossed into the reptilian bin, but if they had been around to think and opine about it, they might have demurred:

http://en.m.wikipedia.org/wiki/Reptiles

“In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the K–Pg extinction wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, as well as many species of theropods (e.g. tyrannosaurs and dromaeosaurids), crocodyliforms, and squamates (e.g. mosasaurids)."

Infraclass Archosauromorpha
Order Prolacertiformes
Division Archosauria
Subdivision Crurotarsi
Superorder Crocodylomorpha
Order Crocodilia
Order Phytosauria
Order Rauisuchia
Order Rhynchosauria
Subdivision Avemetatarsalia
Infradivision Ornithodira
Order Pterosauria
Superorder Dinosauria
Order Ornithischia
Order Saurischia

Dinosaurs are lumped with reptiles:

http://en.m.wikipedia.org/wiki/Dinosaur

“Although the word dinosaur means "terrible lizard", the name is somewhat misleading, as dinosaurs are not lizards. Instead, they represent a separate group of reptiles that, like many extinct forms, did not exhibit characteristics traditionally seen as reptilian, such as a sprawling limb posture or ectothermy.”

"Ship's captains flaunting this"

Flaunt:

http://www.thefreedictionary.com/_/dict.aspx?word=flaunt

v.tr.
1. To exhibit ostentatiously or shamelessly: flaunts his knowledge. See Synonyms at show.
2. Usage Problem To show contempt for; scorn.

Flout:

http://www.thefreedictionary.com/_/dict.aspx?word=flout

v.tr.
To show contempt for; scorn: flout a law; behavior that flouted convention. See Usage Note at flaunt.

John writes:

Dear TWiP Team,

On the latest episode you insinuated perhaps that the host was chosen for his looks and why couldn't they find someone that actually studied parasites. Well, as it happens, the host, Dan Riskin, just did an AMA (ask me anything) on reddit.com His expertise and passion is actually bats but he has become a science communicator full time.

When asked how he ended up as a science presenter his response was this:

"I was working as a scientist in a basement, when the phone rang. A production company was doing a show about evolution (called Evolve, for the History Channel), and they needed "an evolutionary biologist who is not an old man." They'd gotten my name from someone who had seen me give talks at conferences."

http://www.reddit.com/r/IAmA/comments/26p2ge/im_dan_riskin_biologist_turned_animal/

So yes, he was picked for his looks! Showbiz.

Best,

John

 

Robin writes:

Greetings Vincent and Dickson,

A quick note from one of your probable many silent listeners. I am enjoying the TWIV and TWIP podcasts very much! Great learning to supplement my background in ecology and public health. Quick followup on the meaning of "invasive". I think the student of ecology (Vincent) got this one right over the teacher (Dickson). I believe invasive does mean it takes over and outcompetes native species, whereas exotic is something occurring where it isn't natural. There are exotic species that are not considered invasive, although it is probably a matter of degree since any exotic species would compete with natives for resources at some level. Perhaps, that is what Dickson was implying?

Keep up the great work.

Robin

Ecologist

Missoula, MT

Bobbi writes:

Dear Twip group, first I'd like to say that I love your program - great work! Second, I wanted to introduce you to my Parasite Case of the Week blog at http://parasitewonders.blogspot.com

We just hit our 300th case. It's a simple blog - short cases and short answers the following week. I'd be happy to talk to you about it if you're interested. Best wishes,
Bobbi

Bobbi Pritt, MD, MSc, DTMH
Director of Parasitology
Mayo Clinic
Rochester, MN

John writes:

Hello,

iTunes says it has been almost a month since your last episode. It is spring (15 C in Massachusetts) and time for you to emerge from hibernation.

I wanted to call your attention to two related papers on nonhuman parasites. I mean, parasites infecting nonhuman hosts.

I was disappointed to learn from an early TWiP episode that tapeworms do not cause ravenous hunger. So my parents were wrong about the reason for my appetite as a child.

Some rodent biologists (that is, human biologists studying rodents) got to wondering what parasites did to the appetites of their favorite mammals.

Researchers treated African ground squirrels with ivermectin and fipronil. Treated squirrels stopped itching and spent more time eating. Surprisingly, they did not gain weight. Parasites had depressed the squirrels' resting metabolic rate. Parasite-free squirrels had to eat more to maintain normal weight.

Despite not gaining weight, treated squirrels did have a lot more babies. So they were healthier.

Now when is Merck going to donate a billion doses of ivermectin to the squirrels of the world?

References:

Scantlebury M. et al. 2007. Energetic costs of parasitism in the Cape
ground squirrel Xerus inauris. Proc R Soc Lond B Biol Sci
274:2169-2177.

http://rspb.royalsocietypublishing.org/content/274/1622/2169.full

Hullegass, M. et al. 2010. Parasite removal increases reproductive
success in a social African ground squirrel. Behavioral Ecology
21(4):696-700.

http://beheco.oxfordjournals.org/content/21/4/696

Cape Ground Squirrel on Wikpedia

http://en.wikipedia.org/wiki/Cape_ground_squirrel

Johnathan writes:

Dear Drs. Racaniello and Despommier,

Thanks for the wonderful job you do with TWIP and TWIV. I appreciate all the time and effort you put into the podcasts and look forward to each new episode.

I was wondering why you haven't yet given much if any attention to bed bugs on TWIP? They're arguably the most important human parasite in the United States and growing at an alarming rate. Twenty years ago bed bugs were extremely rare in the United States, but now cost the US economy an estimated $3 billion annually. The emergency department where I work is forced to close and decontaminate a main-treatment area room approximately every three days for an average of 17 hours at a time due to a bed bug being found on a patient. While bed bugs are not vectors of human disease, they can cause itchy rashes and less commonly asthma and angioedema. Bed bugs are also associated with depression, social isolation, suicidal ideation, anxiety, nightmares and other mental health concerns. Of all the parasites you reasonable could acquire in the United States, bed bugs would have to be the least desired given their itchy bites, social stigma, difficulty with diagnosis and treatment, and the time and costs associated with eradicating them. The CDC neglected to place bed bugs on their list of the top neglected parasitic infections yet I can't think of a human parasite which more adversely affects the health and well being of Americans than bed bugs. Any thoughts?

Thanks and keep up the wonderful podcasting!

-John Sheele

Johnathan Sheele, MD, MPH, MHS
Assistant Professor, Department of Emergency Medicine
Associate Fellowship Director, Global Emergency Medicine
University Hospitals Case Medical Center
Case Western Reserve University

Jim writes:

Nothing new here, but it's in your region, so just in case it's of use: Ticks in NY

Jim, Smithfield, VA

Heather writes:

Hi Dr.s R&D!

Just a quick clarification: all invasive species are exotic species, but not all exotic species are invasive. Invasive species generally cause ecological, health, or economic problems. Dr. D.'s beloved trout are exotic across much of their current global range. In many areas where non-native trout, such as rainbows, have been introduced they are not considered invasive but they are exotic. Large and smallmouth bass are in a similar situation. However, brown trout in public waterways in the US are considered invasive. Pike in Alaska salmon rivers are one of the most recent and serious human-caused aquatic invasions.
Regards,
Heather

Scott writes:

Dear Dick and Vincent,
Sarcoptic mange is having a significant impact on the current wolf population in the Yellowstone area. In addition mange is also affecting the fox and coyote population in the front range of Colorado, and I suspect the problem extends even further. I think people would enjoy listing to a program on mange. Where did it originate, is it the same scabies mite humans can get? I also have photographs of fox and coyote with mange you could post on your website.
Thanks
Scott

Greg writes:

Greetings professors,

I am a soon-to-be first year veterinary student and long-time lover of parasitology. I just discovered TWiP and am working my way through the early episodes, where you discuss, among other things, the discovery of Trichinella spiralis. You mention Paget and Virchow, but do not mention Joseph Leidy. Leidy, a noted anatomist, paleontologist, parasitologist, and overall polymath (and one of my favorite scientists) is often credited with the discovery of encysted worms in pig flesh. In 1846 (several years before Virchow's work), Leidy made the connection between undercooked pork and human trichinosis, and advocated for the thorough cooking of meat before consumption. Apologies if you touch on this subject in a later episode. I'm working through them as fast as I can! Big fan of the show.

~Greg

 

 

TWiP 74 letters

 voxsciurorum writes:

Dear water-based life forms:

It is 24 degrees in Overland Park, Kansas and I am looking at a slide labeled "Giardia lamblia", part of a museum exhibit on water and human (over) use of water.

I see a greenish lump. I don't know if it's alive. I was not meant to be a diagnostic technician.

The exhibit is produced by AMNH and/or water.org, and located in the Museum at Prairiefire (museumofpf.org). It may be interesting to listeners in the Kansas City area.

Heather writes:

Hi Dr.s R & D!

I think I recall one of you mentioning a younger relative enjoying the game Plague, Inc. during a podcast somewhat recently. With this vague notion in mind I downloaded the game and have been enjoying it ever since. Normally I don't like electronic games, but this one seems to use some very accurate algorithms to simulate the spread of various real and imaginary pathogens, with the ultimate goal of the player being the total annihilation, or enslavement, of humanity. The game is played from the perspective of the pathogen and DNA is the "currency" of the game, which I thought was very clever. Most of the "science" the game is based on seems to be quite well-researched also. I think a discussion of the game, from the viewpoint of scientists who work with microbes and pathogens, would make for a very interesting TWiM or TWiV (there are many kinds of pathogens, besides parasites, including viruses. I have good luck winning with both, even on the "brutal" level of difficulty).

I have just subscribed to Urban Agriculture. I have no idea how I will keep up with four podcasts now! I have no idea how Dr. R. keeps up with four of them! I can keep on top of TWiP and TWiM easily enough, since that is my background but I sometimes have trouble with TWiV, since I only have the most elementary virology background. Perhaps a virology primer, like the early episodes of TWiP, would help me and other listeners who don't know a ton of virology?

Thanks for the great podcasts!

Regards,
Heather

Tristen writes:

Dear Vincent and Dixon,

I have to tell you that I'm a huge fan of Twip and I love listening to you guys! In November 2013 I did my first medical mission trip to Nzara, South Sudan. Vincent you probably already know an interesting fact about Nzara is that it's one of the first places Ebola virus was discovered in 1976! After the short trip I enjoyed the work so much that now I am trying to find funding or sponsorship to leave life here and work in Nzara for a couple years. I appreciate how your podcasts are both educational and entertaining at the same time. My favorite one so far is when you had Peter Hotez on talking about neglected tropical diseases.

I want to request you guys do an episode about chronic malaria infection in children living in sub Saharan Africa and the connection between Epstein Barr virus and the high rate of pediatric burkitts lymphoma diagnosis. This would be a great podcast because it combines parasitology and virology! I learned about this connection after having malaria myself after my trip and find it very interesting. Thank you both for your good work and for giving me such valuable information which I can take back with me to South Sudan!

Truly,
Tristen

If you are interested in seeing the page about my work, visit here:
www.facebook.com/berawenzara

Claire writes:

Hi Dickson and Vincent,

I wrote to Twiv recently but had to also write in here to let you know that without your podcast I would have been totally lost last month when I heard a series of talks on some of the more "popular" parasites (tryps, leishmania etc). I didn't know an amastigote from a billy goat before studying up with your podcasts. Thanks for the help!
-Claire in Seattle

Jim writes:

Here's a link to a short story in our local "Daily Press" for the Norfolk area, about a museum in Tokyo about parasites. Perhaps it's provide Prof Despommier a side trip one day when he's in that part of the world. - Jim; Smithfield, VA

Museum might put you off sushi for a while

For something educational to do before lunch, I admired bottle after bottle of pickled parasites. Some frilled. Some with suckers. Most hermaphrodite. And all gross...

Suzanne writes:

I found lice in my 7 year old's hair about a month ago. My 11 year old had been asking me to check her hair for months and I never could find anything. Checking more closely with a lice comb revealed she did have them. A quick comb through my hair came up positive, too. Yay. Lucky for my husband, he keeps his head shaved.

There was a funny thing I noticed, though. I had been taking a low dose of iron daily and can pretty easily tell when I'm... eliminating... the extra and ought to skip a day or so or when it's all being used up. As soon as we shampooed and combed out the lice, I stopped using all the iron.

Remembering your comments on hook worm and anemia, I looked up lice and anemia. Google had links to a few cases where kids who were very infested showed up at doctors' offices or hospitals with severe anemia that had no other cause the doctors could find. This and the information about lice that mentioned some people have asymptomatic cases (evidently the itching is due to an allergy, not their bites) made me wonder just how long we had all been infested. I've had off and on times of slight iron deficiency since I was pregnant with my youngest and my oldest was in preschool. That's not too uncommon in women and I'm healthy otherwise. This could be totally coincidental, I know, but it's making me wonder.

I'd love to know if anyone has studied how prevalent lice are in the US. I'm starting to suspect that quite a few of us could carry them around in low numbers and not know for... maybe years? It does seem, like bed bugs, that lice are turning up more. At least around here in Central Texas where the weather is barely even worth mentioning. It's summer so it's hot. Seriously hot. But we've been getting more rain this year so that's something.

Peter writes:

Dear TWiP team,
I thought this report from The Lancet Infectious Diseases may be worth a mention:
http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2814%2970794-7/fulltext

Evidence of schistosomiasis has previously been found in 5200-year-old Egyptian mummies, that date has been pushed back a thousand years by the find of a flatworm egg in a grave at a Neolithic settlement site in northern Syria.

Piers Mitchell at the University of Cambridge and his colleagues examined sediment collected from beneath the pelvises of 26 skeletons, all between 6500 and 6000 years old. In one 6200-year-old sample they found a 130-micrometre-long flatworm egg that belonged to one of the species responsible for schistosomiasis.

More information on the Tell Zeidan site:
https://oi.uchicago.edu/support/tell-zeidan-syria

Regards

Rabbit writes:

I just started listening a couple weeks ago, so I'm not caught up yet, but TWiP is the best science podcast I've found. It's so hard to find resources for laymen about parasite that aren't full of misinformation. I've been teaching myself about parasites for a while (I'm autistic, and they're one of my special interests). As is the case with many subjects, it's hard to find resources about parasites that appeal to an audience that's not made up of either experts or complete novices. It's easy to find very basic information, and it's not too difficult to find academic resources, but TWiP is by far the best resource I've found for my level of knowledge.

I have a question: I've read that cat owners aren't significantly more likely to be infected with toxoplasma gondii than people who don't have cats. Is that true, and if so, why/how do you suppose that is?

 

TWiP 74 letters

voxsciurorum writes:

Dear water-based life forms:

It is 24 degrees in Overland Park, Kansas and I am looking at a slide labeled "Giardia lamblia", part of a museum exhibit on water and human (over) use of water.

I see a greenish lump. I don't know if it's alive. I was not meant to be a diagnostic technician.

The exhibit is produced by AMNH and/or water.org, and located in the Museum at Prairiefire (museumofpf.org). It may be interesting to listeners in the Kansas City area.

Heather writes:

Hi Dr.s R & D!

I think I recall one of you mentioning a younger relative enjoying the game Plague, Inc. during a podcast somewhat recently. With this vague notion in mind I downloaded the game and have been enjoying it ever since. Normally I don't like electronic games, but this one seems to use some very accurate algorithms to simulate the spread of various real and imaginary pathogens, with the ultimate goal of the player being the total annihilation, or enslavement, of humanity. The game is played from the perspective of the pathogen and DNA is the "currency" of the game, which I thought was very clever. Most of the "science" the game is based on seems to be quite well-researched also. I think a discussion of the game, from the viewpoint of scientists who work with microbes and pathogens, would make for a very interesting TWiM or TWiV (there are many kinds of pathogens, besides parasites, including viruses. I have good luck winning with both, even on the "brutal" level of difficulty).

I have just subscribed to Urban Agriculture. I have no idea how I will keep up with four podcasts now! I have no idea how Dr. R. keeps up with four of them! I can keep on top of TWiP and TWiM easily enough, since that is my background but I sometimes have trouble with TWiV, since I only have the most elementary virology background. Perhaps a virology primer, like the early episodes of TWiP, would help me and other listeners who don't know a ton of virology?

Thanks for the great podcasts!

Regards,
Heather

Tristen writes:

Dear Vincent and Dixon,

I have to tell you that I'm a huge fan of Twip and I love listening to you guys! In November 2013 I did my first medical mission trip to Nzara, South Sudan. Vincent you probably already know an interesting fact about Nzara is that it's one of the first places Ebola virus was discovered in 1976! After the short trip I enjoyed the work so much that now I am trying to find funding or sponsorship to leave life here and work in Nzara for a couple years. I appreciate how your podcasts are both educational and entertaining at the same time. My favorite one so far is when you had Peter Hotez on talking about neglected tropical diseases.

I want to request you guys do an episode about chronic malaria infection in children living in sub Saharan Africa and the connection between Epstein Barr virus and the high rate of pediatric burkitts lymphoma diagnosis. This would be a great podcast because it combines parasitology and virology! I learned about this connection after having malaria myself after my trip and find it very interesting. Thank you both for your good work and for giving me such valuable information which I can take back with me to South Sudan!

Truly,
Tristen

If you are interested in seeing the page about my work, visit here:
www.facebook.com/berawenzara

Claire writes:

Hi Dickson and Vincent,

I wrote to Twiv recently but had to also write in here to let you know that without your podcast I would have been totally lost last month when I heard a series of talks on some of the more "popular" parasites (tryps, leishmania etc). I didn't know an amastigote from a billy goat before studying up with your podcasts. Thanks for the help!
-Claire in Seattle

Jim writes:

Here's a link to a short story in our local "Daily Press" for the Norfolk area, about a museum in Tokyo about parasites. Perhaps it's provide Prof Despommier a side trip one day when he's in that part of the world. - Jim; Smithfield, VA

Museum might put you off sushi for a while

For something educational to do before lunch, I admired bottle after bottle of pickled parasites. Some frilled. Some with suckers. Most hermaphrodite. And all gross...

Suzanne writes:

I found lice in my 7 year old's hair about a month ago. My 11 year old had been asking me to check her hair for months and I never could find anything. Checking more closely with a lice comb revealed she did have them. A quick comb through my hair came up positive, too. Yay. Lucky for my husband, he keeps his head shaved.

There was a funny thing I noticed, though. I had been taking a low dose of iron daily and can pretty easily tell when I'm... eliminating... the extra and ought to skip a day or so or when it's all being used up. As soon as we shampooed and combed out the lice, I stopped using all the iron.

Remembering your comments on hook worm and anemia, I looked up lice and anemia. Google had links to a few cases where kids who were very infested showed up at doctors' offices or hospitals with severe anemia that had no other cause the doctors could find. This and the information about lice that mentioned some people have asymptomatic cases (evidently the itching is due to an allergy, not their bites) made me wonder just how long we had all been infested. I've had off and on times of slight iron deficiency since I was pregnant with my youngest and my oldest was in preschool. That's not too uncommon in women and I'm healthy otherwise. This could be totally coincidental, I know, but it's making me wonder.

I'd love to know if anyone has studied how prevalent lice are in the US. I'm starting to suspect that quite a few of us could carry them around in low numbers and not know for... maybe years? It does seem, like bed bugs, that lice are turning up more. At least around here in Central Texas where the weather is barely even worth mentioning. It's summer so it's hot. Seriously hot. But we've been getting more rain this year so that's something.

Peter writes:

Dear TWiP team,
I thought this report from The Lancet Infectious Diseases may be worth a mention:
http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2814%2970794-7/fulltext

Evidence of schistosomiasis has previously been found in 5200-year-old Egyptian mummies, that date has been pushed back a thousand years by the find of a flatworm egg in a grave at a Neolithic settlement site in northern Syria.

Piers Mitchell at the University of Cambridge and his colleagues examined sediment collected from beneath the pelvises of 26 skeletons, all between 6500 and 6000 years old. In one 6200-year-old sample they found a 130-micrometre-long flatworm egg that belonged to one of the species responsible for schistosomiasis.

More information on the Tell Zeidan site:
https://oi.uchicago.edu/support/tell-zeidan-syria

Regards

Rabbit writes:

I just started listening a couple weeks ago, so I'm not caught up yet, but TWiP is the best science podcast I've found. It's so hard to find resources for laymen about parasite that aren't full of misinformation. I've been teaching myself about parasites for a while (I'm autistic, and they're one of my special interests). As is the case with many subjects, it's hard to find resources about parasites that appeal to an audience that's not made up of either experts or complete novices. It's easy to find very basic information, and it's not too difficult to find academic resources, but TWiP is by far the best resource I've found for my level of knowledge.

I have a question: I've read that cat owners aren't significantly more likely to be infected with toxoplasma gondii than people who don't have cats. Is that true, and if so, why/how do you suppose that is?

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