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TWiP 42 Letters

Jesse writes:

Dear Doctor's Racaniello and Despommier,

Huzzah! I have tracked down Dick's missing book on tropical medicine, or at least another copy of said book. While listening to TWIP #40, my ears perked up when Dick said he had lent a book to a student only to have it never return. A quick Google search found the following book: "Tropical Medicine and Parasitology: Classic Investigations" by Mott and Kean of Columbia University circa 1974, which I believe is the book in question. I managed to find a copy online for a steal (less than $10, including shipping!) and immediately ordered it. In 4-14 business days, I should receive a copy, which I will gladly send along to Dr. Despommier as a token of my gratitude for everything that he has done for me (more than you would think).

As a pharmacist working the night shift at a popular chain store, I quickly grew tired of listening to internet radio at night and needed some further stimulation. Your podcast was one of the first that I found and I quickly listened to every episode (multiple times even). This podcast, along with a few other life changing experiences, has inspired me to completely change the direction of my life. I now have solid plans in place to go back to medical school (once my debts are knocked down a bit) with hopes of becoming an infectious disease specialist. My dream is to join Paul Farmer's organization (Partner's in Health) and practice "tropical medicine" while helping those most in need.

Thank you both for all that you do and for taking the time to read my email. If you reply with a mailing address for yourselves at Columbia University, I will gladly send along the missing book once it arrives. As always, looking forward to your next TWIP!



P.S. Are you missing any books Dr. Racaniello? Your work on Polio is greatly appreciated, as my grandfather suffer's from a mild case of Polio myelitis -- so it is obviously a topic that is near and dear to me.

Keely writes:

Hello Dr. Racaniello.

To introduce myself, my name is Keely, and I'm currently a second-year graduate student at UCLA. I work on parasitic worms under Elissa Hallem, and I TA for the undergraduate parasitology class taught by Patricia Johnson.

First off, thanks for all the podcasts. I really enjoy them, and they keep me reading new and interesting papers that are a bit outside of what is usually on my radar. Also, though I was a microbiology major with a strong interest in parasites, my undergraduate institution lacked a full parasitology course, so I learned most of my parasitology from my own reading. I really appreciated the review that TWiP gave me before I started working on parasites for my graduate program.

Anyhow, I was listening to an older episode that I missed somehow, and you mentioned at some point having listeners on the show as a guest. If you ever decided to try and do this, I would love to toss my name in the hat.

Thanks again!

Michael writes:

I am 63 years old. I became ill while serving in Vietnam at the age of 20. For 43 years I have been going to one physician after another physician. Army, VA and private physicians have never been able to identify or diagnose my illness correctly, because every treatment or medicine they gave me, oral and topical, never worked.

For years I argued that I felt that it was parasitic, but the VA eventually convinced me that I had Agent Orange related illnesses and that my idea of parasites was not only futile, but hypochondriasis (a diagnosis, which they actually gave me).

Well, I am still hopelessly suffering. Boils are breaking out all over my body, particularly on my scalp and arms, and I truly feel that I am in late stage severe and chronic Parasitosis, but the VA has me diagnosed with Delusional Parasitosis. Last year in November, I had three very large lesions/boils that grew so large that they burst and left large continuously draining holes (blood and infection) in my arms and scalp. I became interested in the fluid samples and began collecting them in small plastic jars with tight lids. I took these samples to the VA and asked them if they would have them tested/cultured or examined under a microscope to see if anything could be determined or diagnosed. They refused and said that their blood tests for parasites was all that they needed and it had come back negative and there was nothing else that they could or would do. So to date, after years of complaining and arguing, all that they give me in medicines is anything medicines for para

After that I decided to buy a USB 200x Microscope that could take photos of what I focused on underneath the lens, which I found on Amazon marked down from $250 to $80, and examine these fluid collections on my own.

Doctors Racaniello and Despommier, both of you may be surprised. Thus far (for five months now), I have 200x photographed over 3000 pictures of the fluids draining out of these non-healing, large, deep, open wounds. In January I took nearly 1000 (what I had at the time) of these photos to the VA and they wouldn't even look at them, notwithstanding that they also did not give me the necessary wound either. If what I am looking at in the photos is correct I am acutely infected with millions of nematode microfilariasis worms and flukes.

Lastly, is it possible for me to send you a few of these photos (I can send them all on a snailmail CD or post them to Photo Bucket) for you to look at and advise me on whether or not they are in fact one or more of the over 10,000 nematodes that find humans as a desirable host? Thank you.


Raphael writes:

Good day, doctors!

I did not hesitate to write this right after hearing an email you responded on TWiP 39.

I would like to thank cytotechnologist Rebecca for the comment and Dr. Dickson for additional info on how tricho is vertically transmitted from mothers to female newborns and how it could be lifelong. Not so many years ago, I had a rare opportunity to have a urinalysis result that came out which was trichomoniasis positive. The female patient who was in her early twenties denied that she had no history of sexual contact but knowing very well that tricho is a sexually-transmitted infection, I immediately did not believe her. Nevertheless, I treated her with an antiprotozoal drug.

Now that I know how tricho is transmitted, I owe that patient my apology.

Tracy writes:

Dear Dick and Vincent (if I may be so bold)

I listened to the podcast on Leishmania this week as I prepped for my Leishmania lecture in Medical Microbiology. I was struck by Dick's comment that we didn't know what the amastigotes ate while in the the phagolysosome. I ran across an annual review in Microbiology article that seems to address the metabolic needs and potential nutrients sources for the amastigotes while in the phagolysosome.

Here is the link to the paper: (Metabolic Pathways Required for the Intracellular Survival of Leishmania)


I enjoy your podcasts and my students find them an easy way to approach very complex material.

Keep up the good work!

Laura writes:


Firstly i would like ot say that I followed your podcasts whilst i undertook my undergraduate degree and found them useful for revision. I am now starting a PhD at Nottingham University in England this year and would like to thank you for providing such great podcasts.

I would like to ask, as mosquitoes carry a number of parasites/viruses that can infect humans, is it possible for one mosquito to infect a person with more than one species of parasite/virus, for example could a person get malaria and leishmania at the same time from the one mosquito?

Jon writes:

Ok, this sounds rather unpleasant - but may explain a lot about the world :)

The Brain: Hidden Epidemic: 
Tapeworms Living Inside People's Brains


Suzanne writes:

Maybe Dickson knows or maybe someone else has mentioned it, but if you wash immediately with soap and cold water poison ivy oil washes off more easily. Wash all your clothes in cold water, too. Most people want to wash with warm water (I've done it and boy did the rash spread) but cool or cold water works best. I hope his has cleared up by the time you get this!


Jim writes:

Dickson mentioned this 2 vol set on the last TWIP. This link from the World Catalog may have specifics as well as where Vol 1 can be bought, and cheaply too, it appears. Volume 2 is in the World Cat database, but not linked to any library or store -- odd. The key thing is that the title may be "Tropical Medicine and Parasitology." I found a few Vol 1's, but no Vol 2. Might a Vol 2 be sold as a Vol 1? Here is a link that at least shows a Vol 1 & 2 set has at one point been listed on Amazon, so a periodic search may eventually be productive. I like looking at old books and will keep an eye out in this area. Maybe a mention on a TWIP would alert listeners to also watch for the set. Not an expensive item.

Ref deer flies: I have used these tred-not patches on my hat for several years and they are quite good. Just ordered another big batch. Sound like something Dickson can use, if he is not doing so already. Only negative aspect is that they are only good for one day. The last of my current batch were purchased last year and worked just fine.

Beautiful shows, all!


Smithfield, VA

Stephen writes:

This is actually for TWIP, FYI

(BTY: It's not easy to send to TWIP from the Nature app, because it assumes an email address.)

Bovine TB disguised by liver fluke

Nature News,Published online: 22 May 2012; | doi:10.1038/nature.2012.10685


Meika writes:

I have been one of your silent fans for about a year now. And I absolutely LOVE all three of your podcasts. I am a scientist at heart and by training, but a horse trainer for my living. I recall a past podcast about a dressage barn that had an outbreak of toxoplasmosis, and I am trying to search for it, but Toxo is a very popular subject for you guys and the list is long. While I am willing to listen to all episodes again to try to find it, can you give me a hint as to which episode it was and shorten my search?

Your show has been an inspiration to me as well as a fun link to my past life as a scientist. Listening to TWIM has prompted me to go on a several days long spree of reading reprints of my grandmother's research. The earliest I can find is 1933 and she is the lead author in The Journal of Bacteriology on carotenoids and Vitamin A in bacteria. She also was interested in nutrition and color inheritance in Serratia and published her research for four decades. I cant help but think that she was the rare woman bacteriologist who led by example for so many women back then. Thanks for keeping me interested and helping me know my grandmother better.

Meika (pronounced: mica, like the mineral.)

Mike writes:

Doctors, I have recently discovered podcasts and the very first thing i searched for was one on parasites. I have been fascinated with parasites since grade school and will be starting my 3rd year of veterinary school in the fall so i was very excited to see a podcast devoted entirely to parasites. granted a bulk of my parasite knowledge is animal based i still very much enjoy TWIP. I started your first episode and have just finished the episode on hookworms. a few things i wanted to bring up, from the perspective of a budding veterinary parasitologist. First: A. caninum is capable of infecting young pups through the bitches milk and i was wondering if any human hookworms have been documented to do the same, at least for animals, hookworms can also be contracted from eating the 3rd larval stage (generally pica) or from eating a variety of other animals that have eaten the 3rd larval stage and act as a transport host, for example, the larva eaten by a mouse, enter a hibernation state until a cat or a dog comes along and eats the mouse. as the tissues are digested away the larva wakes up, receives environmental cues and will proceed to develop to an adult, this is a particularly common way for cats to contract A. tubaeforme given their predatory nature. Has anything similar ever been documented with a human species of hookworm?

Second: as to the question of prevalence of hookworms in dogs in America, yes they are definitely endemic. they are a problem across the nation especially shelters, as are whipworms, ascarids, coccidia.

Third:in one of the episodes on tapeworms Dick was comparing the pork tapeworm to the beef tapeworm and mentioned that horses and cattle are different from pigs and asked Vince why. Dicks answer was that cattle and horses are both ruminants while a pig is an omnivore, i don't know if this was an accident but horses are not ruminants, they do not have the complex foregut fermentation system of cattle, sheep, goats, deer and other similar animals, horse are hindgut fermenters and do a bulk of their digestion in their colon and cecum (appendix) but both are herbivores.

and last, to Vince, you had peppered Dick with questions on what animal species had what nematode parasites, to broaden your list, ascarids are found in horses, pigs, cats, dogs, cattle, raccoons, wild canids and felids and mostly any other mammal. hookworms are just as ubiquitous in the animal kingdom. that's all for now but i am sure i'll write again, keep up the great work gents. I understand that this is a long email and will not be offended if you don't read it on the air but i would greatly appreciate answers to my questions if possible

Mike writes:

Doctors, again i write to you because a few things had slipped my mind while writing my last email. Dick, when you were describing the live cycle of ascaris, you said there was an operculum on ascarid eggs. I have seen many ascarid eggs of several species and have never seen an operculum, did you miss speak or have i just not been looking carefully enough? or is it specific to A. lumbricoides? it has always been my understanding that the operculum is rather rare in nematode species save members of the orders Oxyurida and Enoplida. speaking of Enoplida, one of the many parasites we discussed in parasitology course that is part of our curiculum was Dioctophyma renale, the giant red kidney worm, a particularly cool video of a dog in canada that was unfortunate enough to contract a few of these has been posted on youtube: http://www.youtube.com/watch?v=5ob6S_EqR1c Has there ever been a case in people that you know of?

Lastly, I just listened to the Strongyloides podcast, do pigs, like people often pass the larva in their stool but in the veterinary world they are the exception, most of the time in other domestic species the eggs are what are passed does this ever happen with people? have you ever seen a Strogyloides egg? This particular parasite can be debilitating and even fatal to piglets but with the modern management techniques in the American swine industry the problem has ceased almost entirely.

thanks again for humoring me gents,

Daniel writes:

Hello again professors. Sorry to keep bugging you but I thought you might be interested in a website I happened upon the other day.
It's a crowd sourced pseudo-video game designed by UCLA students in which the players have to identify RBCs that are infected with malaria. Here's a bit of text from the site and the link.

The Idea

Analysis and related diagnosis of medical images, regardless of the source and imaging modality, are tasks that require a great deal of expertise, demanding significant training of medical practitioners prior to being able to accurately interpret and diagnose such images. This is particularly true in analysis of microscopic data, creating challenges in resource-limited settings and developing countries, where properly trained health-care professionals are difficult to find.

We have shown that by utilizing the innate visual recognition and learning capabilities of human crowds it is possible to conduct reliable microscopic analysis of biomedical samples and make diagnostics decisions based on crowd-sourcing of microscopic data through intelligently designed and entertaining games that are interfaced with artificial learning and processing back-ends. We demonstrated that in the case of binary diagnostics decisions (e.g., infected vs. uninfected), using crowd-sourced games it is possible to approach the accuracy of medical experts in making such diagnoses.
Specifically, using non-professional gamers we report diagnosis of malaria infected red-blood-cells with an accuracy that is within 1.25% of the diagnostic decisions made by a trained professional.


Wish you both the best and let me apologize again for bombarding your inbox.


Nick writes:

Hi Vince and Dick,

I'm writing hoping that you haven't already been flooded with emails regarding heartworm treatment and resistance, and if you have, maybe I can still be able to contribute something. I'm a dual degree student (DVM/PhD) at Cornell University and am studying the mosquito vector ecology of heartworm. As your listener mentioned, there have been some reports of persistent microfilaremia in dogs on preventive medication. Some of the issue has been shown to be due to lack of owner compliance to administering the drug, but, after controlling for that, there have still been dogs identified with persistent microfilaremia despite preventive treatment (and often after the adults have been killed or removed), which currently is the only standard method to clear the microfilariae.

This loss of efficacy is specifically of the microfilariae to clearance, not to melarsomine (Immiticide), which is the adulticide. Ivermectin formulations used as preventive/microfilaricidal, which you eventually got to during the podcast anyway! There have been some studies looking into the effect of doxycycline on clearing the Wolbachia in Dirofilaria immitis to reduce their ability to reproduce and possibly reduce microfilarial and larval fitness for transmission, which I thought you'd find interesting.

I'll be sure to chime in on veterinary topics or, more likely, vector biology topics that I know something about. Also, I was surprised to hear that Dick came to speak at Cornell but I had missed it! I'll have to be more attentive next time,

Keep up the good work!


Alberto writes:

Dear Parasite Hosts

I thought Dickson would be interested in this story from ABC's ( Australian Broadcasting Corporation) Science Show which features an interview with A/Prof Daryl Davies of USC, LA in which he discusses the potential use of ivermectin for the treatment of alcoholism.


I found this recent article in Neuropharmacology from the Davies lab which describes the experimental use of ivermectin in a mouse model of alcohol dependence.


I quote from the abstract:
".. in the present study we investigated the effects of this agent on several models of alcohol self-administration in male and female C57BL/6 mice. Overall, IVM (1.25-10 mg/kg, intraperitoneal) significantly reduced 24-h alcohol consumption and intermittent limited access (4-h) binge drinking, and operant alcohol self-administration (1-h)."

The mechanism of action appears to be via antagonism of a purinergic receptor in the brain. In the interview, A/Prof Davies explains that in parasitic organisms, the drug acts by stimulating an excitatory glutamate chloride channel.

Keep up the great work guys.


Ethan writes:

I found this in the mail today from my water department and had to forward it to you guys. Looks as though my city's water is clean of any cryptosporidium parasites, but inhabitants of other middle Tennessee areas perhaps are not so lucky!



Peter writes:

Watching 'Origin of Us' a BBC2 documentary on Human evolution. In Episode 2, 'Guts', the host Dr. Alice Roberts mentions an interesting hypothesis relating to tape-worms.

It appears that the lion tape worm and human tape worm are very closely related. A DNA study is used to determine the time of worm
speciation. It is assumed that around this time Humans began to steal or eat the same prey as lions. Eventually the worm evolves from Humans as the intermediate, host to becoming the definitive host. Aprox 800k to 1.7 million BCE.

She does not cite the work but, being a BBC doco, I have no reason to doubt the work is genuine and published somewhere.

Novel idea to use tape worms for plotting meat eating in Humans.

Stephen writes:

Might this help to learn how Cobbold named Loa loa.

I don't have access to the journal, and didn't find the full text on line. Pubget.com finds it at the nearest university library, but it's $31.

A bit steep just to satisfy curiosity.


Rohit writes:

Dear Dr Racaniello and Despommier,

I listened to the fascinating episode Worm in the Eye: TWIP 40 earlier this week. Coincidently, I saw this news story, about a doctor taking out a worm from the eye in Mumbai India today. http://www.bbc.co.uk/news/world-asia-india-18640495

I thought that it would be interesting to hear Dr Despommier's expert comments about this worm/case. I apologize if this worm has already been discussed and I have just not caught up with that particular episode yet. I am curious if the doctor's statement "The worm could have travelled deeper into the eye or gone to the brain through the optic nerves, which could have been fatal" is true. Being a virologist, I know that Polio and other viruses travel through nerves but can worms too travel through nerves?

Dr Despommier is a wonderful story-tellier. I find it amazing how much he can remember. Keep the awesome worm-stories coming along with some very intriguing questions from Dr Racaniello.



Postdoctoral Fellow, Chandran Lab
Department of Microbiology and Immunology
Albert Einstein College of Medicine

Ethan writes:

Dickson mentioned how crazy it is that ticks can live up to 50 years in a dormant state without taking a blood meal, and it immediately reminded me of this:


After subjected to conditions within a vacuum and being blasted by an electron beam, the tick keeps ticking.

Joann writes:

Hi Drs. Racaniello and Despommier,

Great podcast!

I'm a graduate student in epidemiology and am completing my practicum this summer working as a health inspector in a coastal town. One of the health agents I work with used to be a chef at one of the local restaurants. She described to me (warning this is gross!) how they used to use tweezers to pull out little (~1" worms) from cod and swordfish that would later be cooked in served. My questions for you: do you have any idea what these worms might be? And, is there any chance that ingesting them (or perhaps eggs/larvae, etc.) of these worms would make humans sick? Regardless, still pretty nasty.

Keep up the great podcasts! I have a long commute usually and have been twipping and re-twipping.



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