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TWiP 24 Letters

Betsy writes:

Dr.'s Racaniello and Despommier,

Hello! To start off like so many of the messages you receive thank you so much for this wonderful podcast! I'm a huge fan of both TWIP and TWIV and have listened to every episode to date in both. It's fantastic how you present all of the information in a conversational way that is understandable for such a diverse audience of listeners. You two, along with your cohorts on TWIV, continue to feed my interest and very very limited knowledge in the fields of parasitology and virology.

I am a medical and biological illustrator/animator who became very interested in the field of parasitology while working on my graduate thesis at the Johns Hopkins University School of Medicine. My preceptor, Dr. Rhoel R. Dinglasan, an associate professor at the Johns Hopkins School of Public Health (JHSPH), who besides being incredibly intelligent and enthusiastic, sparked my fascination with the malaria parasites, and the field in general. And thanks to you I can continue to stay up to date and expand my knowledge in this field.

That being said I thought you might enjoy the new issue of the JHSPH magazine. It's all about malaria! I really enjoyed articles and reading about what research is being done and also why some of the researchers focus on various aspects of combating this disease, such as control vs. eradication. Plus there is the main illustration that beautifully depicts the life cycle of the malarial parasite that was created by an incredible medical illustrator Jennifer E. Fairman. There is an interactive version of this illustration on the magazine site too. To view this issue please follow the link below:

I thought that you would enjoy this illustration too as you have mentioned aspects of my field on both your podcasts in the past. Specifically you have commented on molecular animations by David Bolinsky of XVIVO who is at the top of the field in this area. You might already know about this but in case you do not, the web site showcases some of the most beautiful molecular animations out there. This site has a two-part animation by another amazing medical animator, Drew Berry, on the life cycle of the malarial parasite. Don't despair Dr. Racaniello there are many animations on there about viruses there too!

Again thank you for putting all of the time and effort that it must take to prepare and deliver such a fantastic podcast! I'm looking forward to all of your future episodes!



P.S. In appreciation for your sharing of knowledge and enthusiasm for science I've attached an illustration of mine for you of the malaria life cycle with in the mosquito. I know it's not enough to repay you for your generous service but it's a start.

Weissbrod Studios

Helen writes:

I am a med tech and a member of a group of people with immune diseases who is interested in helminithic therapy. We listened with great interest to the TWIP on Trichuris trichiura, which some of us are already using. I wanted to ask you when you will be covering hookworm, and if you could discuss the therapeutic benefits of Necator americanus, which some of us are also using. I liked the Trichuris podcast so much I am going back and listening to all the old episodes. I am interested in how trichinella could be used therapeutically. I believe you said that if the larvae are injected directly into skeletal muscle, they would immediately infect the muscle cells. Would this mean that by bypassing the migration phase, the infection would not cause pathology?

I have a family member with eosinophilic esophagitis, which is a disease that fits the hygiene hypothesis perfectly: sudden recent increase in incidence, atopic disease, more common in children, and the eosinophilic response is supposed to fight off parasites. This is a horrible disease that causes much suffering and often leaves the person unable to tolerate any food, needing a feeding tube and elemental formula. Do you know anything about the incidence of this disease compared to the incidence of parasites worldwide?

Keep up the good work,

Rich writes:

Hi TWiP fellas,

I should be working but I'm procrastinating by writing you.

I'm finally hooked on TWiP. Great show. Sorry it took a while. Until now my taste in podcasts has been a bit narcissistic.

I know this is a family show, but I really need to know if tapeworms have sex. You keep talking about "eggs" but my sense is that these are not haploid nor are they zygotes, but rather multicellular larvae encased in a shell. Right?

So do tapeworms have a haploid phase? Are there sexes? Assuming there is a haploid phase, when, where and how during the life cycle does fertilization take place? If tapeworms are hermaphrodites, do they self-fertilize, or is there a chance to mix it up with other worms, or both?

Thanks and keep up the good work.


Richard Condit
Department of Molecular Genetics & Microbiology
University of Florida
Gainesville, FL

Laura writes:

Hiya im Laura from the UK, studying Zoology and wanting to comtinue onto an MSc in parasitology. I was wondering are there parasites of parasites? would microsporidia be a cadidate for this?

Ryan writes:


Just wanted to drop you guys a line and let you know I enjoyed the podcast. I found TWiP while actually looking for a podcast about photography, but gave it a listen anyways. I'll be downloading every episode from now on. Parasitology was my favorite class as a undergrad. Thanks for the work you do!


Todd writes:

Hey Docs!

I'm a computer programmer who listens to podcasts on my long commute. The highest science education that I've had was college Chemistry. As an Electrical Engineer the science classes we took tended to not be biology oriented, so while some of it is over my head, to say that I find biotech and molecular biology fascinating is an understatement.

On to my question: I was born in 1970 in southern Louisiana. My uncle had a horse and we (me, my Dad, my uncle) would scoop the manure out of the stall and put it into a pile on the side of the horse barn. Some months later, after the manure had been exposed to the weather and sun-dried, we'd scoop it into the wheelbarrow and put it, along with composted grass clippings, in the garden as we tilled the soil for planting. I was wondering what kind of worms and/or other parasites we might have been exposed to by using horse manure to fertilize our vegetable garden. If I'm understanding things correctly, I don't think there is any danger from worms lasting long enough to get into our veggies and infect
us, but what about direct contact when handling the sun-dried manure (shovels and gloves, but still "stuff" happens)? And is there really anything to fear other than worms? I am in good health, so I think the answer is probably no, I'm just learning for learning's sake.

P.S. Lately I've been listening to the FiB, TWiV, and TWiP podcasts to the point where I'm neglecting my techie podcasts. You guys are causing me to lose some of my geek creds :-)

Regards... Todd

TWiP 23 Letters

Eric writes:

Dear Vincent and Dickson:

I am retired (40 years in computers) and so I have lots of time to study
anything that interests me. It's good brain exercise and I simply loved
the 3 shows on Trichinella worms. What a fantastic job of explaining a
truly incredible piece of evolutionary 'design' - and the work of a
brilliant scientist who figured much of it out. Twip 3-5 is right up
there with Edward G. Robinson in Dr. Ehrlich's Magic Bullet. Following
along with the sketches etc. on the website was great. Vincent asked all
the right questions just as I got confused, which made it feel like I
was there one on one with Dick. I didn't feel I needed to have any
pre-knowledge. Simply a perfect presentation! Nothing like the biology
classes that bored me in high school.

My road to TWIP began by looking for interesting mp3s for my daily
walks. I found twit with Leo Laport. which led to futures in biotech
where one or both of you had been a guest.

Next was twiv which fascinated me because the study of viruses and all
that DNA and RNA stuff was so reminiscent of when I would solve computer
problems by getting out the machine code debugger. None of the younger
guys know that old stuff anymore (they're all 2 layers higher up). But,
just like in a virus, if you know the exact instruction that caused the
problem, you could walk your way back up to the higher level and find a
fix - i.e. intervene and cure the bug. Not always so simple, of
course, sometimes you had to be clever and think of ways to force the
bug out into the open or look at the preceding steps, but the idea seems
similar to the techniques Dick described, especially the "sync" trick he
used. That was a cool one.

For what it's worth, you guys would have made marvelous system geeks,
maybe working in some shop in Taiwan reverse engineering the latest
chips. After all, it seems that's what you're doing. You're working out
the APIs of life, without a manual by watching the ins and outs and
reading the machine code.

I can't help wondering why Dick didn't try to sell his idea in the
marketplace - the one about how to possibly cure diabetes described in
twip 4. Maybe some wealthy person with a child who has the disease might
become interested as a sponsor.

Well, now we have the internet and TWIP, so perhaps this is the best way
to reach out with your ideas. I hope someone takes the ball given the
tremendous lead you've given him or her and solves this problem. Maybe a
Craig Ventor researcher will hear your idea and code up a new bacteria
with some genes taken from Trichinella.

After all, just as computer tech is nearly all software today so it
seems biology has become a variant of IT (e.g. Ventor's Bacteria Shell).
I expect to see a Visual Biology program in the not too distant future -
just click and drag to insert a Sinusoid creating protein.

Regards, and thanks for the great brain exercises!


Jim writes:

Dear Professors, thank you very much for your fine podcasts. I'm a physicist, about the age of Dr. Racaniello, but my career since graduate school has been in public policy, not academia. Since I never took the time to study parasitology, your conversations are new and often astonishing to me - the world is truly wondrous.

And my two questions: First, in your (fairly) recent podcast on pinworms, Professor Despommier explained that each mammalian species seems to have their own pinworm. Do the other mammals also show a clearing of their pinworm parasites at a time analogous to puberty? Or is that an unusual characteristic of our human-pinworm relationship?

Second, a broader question suggested by an odd - to me - phenomenon in insect parasitism: As you probably know, parasitic relationships among insects are quite common. The most familiar are various small wasps (hymenoptera) that parasitize the caterpillars of moths or butterflies (lepidoptera), and which are often useful in controlling lepidoptera pests. The United States often searches for such a native parasite of newly introduced, economically damaging moths, and introduces them to control the moths

In some cases though, even the right parasitic wasp, effective in its native range, doesn't effectively control a new, invasive species of moth in a new region. Hyperparasitism is quite common in these insects - there are yet more species of parasitic wasps which parasitize a range of other wasps parasitizing the caterpillars in a region. They search out the eggs or larvae of the wasps laid in or on a caterpillar, and the hyperparasitizing wasps then infect those eggs or larvae. This can, too commonly, reduce the population density of the wasps parasitizing the caterpillars, and render them ineffective in reducing the number of caterpillars.

Does this occur more broadly? That is, do any of the human parasites you will cover have their own parasites? If they did, or could, that would seem to offer a different path to controlling our parasites.

Finally, on your rate for creating new podcasts - please continue to produce them at whatever rate you can tolerate! I am quite willing to wait to hear your conversations, and would rather wait longer to have more than to have you burn out trying to meet some schedule.

Take care,


Peter writes:

Malaria parasite caught in the act:

Luke writes:

Hello professors,
I saw this paper in Cell Host and Microbe where the authors have captured a movie of a malaria parasite invading a blood cell by using a combination of heparin and E60 to boost the number of events. The paper, itself, I believe is closed access, but the movie is available through this New Scientist article:

Thought it might work well as a pick of the week for twip. Thanks so much for opening up the world of parasites to me through this podcast.

John writes:

Dear Doctors,

I'm sure you will have this in your feeds or sent in by several folks but just in case...

A video of plasmodium entering a red blood cell. Really a series of stills strung together as a movie. Quite fascinating to see the effects about 3/4 of the way through.

Thanks again for the entertaining education and a belated happy new year to the crew.



PS "Another TWiP is spiral" is clearly a masterpiece tagline and should be reconsidered.

Arsen writes:

Hey! Just listened to twip#21, where you said, that the only way to verify, if Ascaris lumbricoides inhibits growth in humans would be to infect a bunch of kids with it and watch them grow (which wouldn't be ethically acceptable). I don't think that this is the only way. Because we have areas with high worm infections already, the incidence of worm infections in an area should be inversely correlated to average height of people living in that area (of course, we should correct for dietary factors etc, but we should know the data for those factors by now)

Keep it up


TWiP 22 Letters

Luca writes:

Hi Vince and Dick,

I am an avid listener of your podcast (and Twiv, too) - I started something like six months ago and I've retrieved all those whose title sounded interesting. I am not a parasitologist myself, though I am a pharmaceutical (computational) chemist with a deep interest in biology and virology. My passion for parasitology blossomed upon reading "Parasite Rex" by Carl Zimmer, and was re-stoked by your wonderful podcast. By the way, that book would definitely make for a wonderful pick of the week. Please excuse me if my english may seem a bit long-winded, but my brain is wired for Italian, where long, convoluted, interdependent phrases are the norm. And even after ten years of life abroad I can't seem to shake the habit.

I was listening to your latest when you were talking about the scientists of Antwerp's Tropical Disease Institute and their attempt at fighting L. Congolense. I happen to live in Mechelen, a Belgian city halfway between Brussel and Antwerp. One of you two (Dick, perhaps) suggested raising zebras and eland for meat rather than cows, in Africa. I believe this is already happening, although in a limited fashion. Africa is probably a bit too far for meat grown there to reach you, or maybe American habits are different. Here in Belgium, it's rather easy to find zebra's, ostrich, antelope's and even crocodile's meat in most supermarket. The origin is usually South Africa, where I believe they're farmed or at least reared in semi-wilderness. Needless to say, I've tried them all... As a native of the mediterranean island of Sardinia, I am deeply passionate about thin sliced horse meat quickly roasted on the fire, seasoned with garlic, olive oil and spicy 'peperoncino', or chili as it
's known to you. I am probably a very good parasite host, since I like my meat almost rare and when abroad I nibble on wild plants, from Rwanda to Turkey. What's the point is going to see Gorillas if you don't try their wild celery?

Thanks so much for your effort in diffusing your knowledge, I'll keep listening and will suggest your podcast to my research group and people in compoanies who sometimes are hard-pressed to find the time to keep abreast of interesting literature.

As for This week in Physics, I guess that field is pretty well covered by the various Nature and Science Podcasts and the likes of them... What's hard to find in my opinion is a decent podcast in the field of drug dveelopment. Nature runs a couple but they're sporadically updated, so they don't cut it for me. If you have any suggestion...

All the best with your endeavour


Debora writes:

You were going to describe how the trichuris trichuria causes anemia; not from blood sucking, but you mentioned within the bone? But you never elaborated. Could you explain?

I've been using necator americanus for my Crohn's disease with good success for 3 years now. I lose my worms within 6 months, however, and the Crohn's returns. I recently tried adding trichuris suis ova, and had a very negative reaction, which was unexpected.

You made a few mistakes about Crohn's... it is not located only to the colon, it can affect the entire digestive track, from mouth to anus. Ulcerative colitis is colon only. Both are IBD, and both trichuris and hookworms are being investigated currently as "therapy" .

Thank you for your interesting information and for mentioning the hygiene hypothesis. I learned more about whipworms and would like to hear more their relationship with allergy and autoimmunity.

Herbert writes:

I was also able to achieve remission from Crohn's after getting hookworms and whipworms. You can follow my progress here:
Also, there's a wiki page that contains a ton of information on this topic, including helminthic therapy providers:
A whole lot of research articles on helminthic therapy can be found here:

Richelle writes:

Thank you Vincent and Dickson for your fantastic podcast. I am a police officer with a hobby in science. Trying to squeeze in some study and was in a panic about how I would cram for my microbiology exam next Thursday since work is sending me away for 4 days. I will be sitting in airports for much of that time. But now I have all of TWiP and many TWiV. I already listened to them all but will listen over and over while I am away. I wish you had more on schistosomas and fungi. I love the history you include in your information and also the references to scientists currently working on various things. Vincent asks almost all of my questions. I hope you dont get bored doing these podcasts because I will be a faithful follower from now on. I looked to vote for you in the podcast awards but you weren't there. I voted for the Brain Science Podcast instead. Am sure you will be there next year.

Love from Richelle in Canberra.

TWiP 21 Letters

Carolyn writes:

Dear Dick and Vincent,

Thank you very much for discussing my question on Crypto and the Miox disinfecting system on the last podcast. I appreciated the additional information.

My daughter sent me this link to a CDC report on killing crypto oocysts with miox.
I know you would probably still recommend the filter, but I just want to be sure of all my options.


Chad writes:

One of my friends posted this movie on Facebook, and I thought you would be interested.

Eric writes:

Hi Vincent and Dickson:

I'm up to TWIP 13, and I'm learning quite a bit. Got a couple questions:

1. I understand that sickle cell trait affords some resistance to malaria, could you comment on this. I've heard that if you have 2 (genes?) you get the sickle cell disease, but if only 1, just the trait and it's speculated that this evolved for protection against malaria. Is this still the belief?

2. I thought sex evolved to provide an organisim with a faster way to adapt. With sex there are more slightly different members of a species and so allows for faster adaptation in a crisis than would clones.

I'm confused about sex in the single celled parisites. If there's only a single cell, and it makes both males and females, how does this result in more choices. Where do these join up in sexual combinations that are not all from the same "mother" cell. If a cat eats a rat that is infected with Toxoplasma, how did the rat get more than one set of different offspring. Does it have to be infected multiple times by different lines and then meet up in the gut? Or eat multiple infected rats? Ditto for malaria.

Keep em coming, I am still listening even though for a few moments I worried that my flu this year was malaria. Fortunately, no big headache or backache. But I did wonder about whether mosquitos were still dangerous in the "winter" in S. California. How cold does it have to be for them to die. It's been no lower than 45 deg F. at night here in L.A.

Regards, and great job,


Alan Dove writes:


This might be interesting to cover on the next TWiP.

-- Alan

Jim writes:

For TWIP in case you didn't see it. How difficult might it be to use this approach to cure/prevent river blindness?

Smithfield, VA

Study sheds new light on river blindness parasite
via e! Science News - Health & Medicine on 1/12/11

The team found that a bacterium inside the worm acts as a 'disguise' for the parasite, resulting in the immune system reacting to it in an ineffective way. The bacteria protect the worm from the body's natural defences, but once the bacteria are removed with antibiotics, the immune system responds appropriately, releasing cells, called eosinophils, that kill the worm.

Jim writes:

Dick and Vince:

I understand bed bugs can be killed with heat. This article about lice indicates dehydration is the killing mechanism. I wonder if the same applies to bed bugs and the heat just hastens the process. If so, might running several dehumidifiers and a heater in a sealed room be a faster means of ged bug disinfection.

Smithfield, VA


TWiP 20 Letters

Jim writes:

For TWIP file (link).

Smithfield, VA

Marc writes:

Dear Vince and Dickson

Wonderful job on both podcasts. I just finished listening to the Cryptosporidium episode. I love all topics regarding the apicomplexa, and unless I am mistaken there is a fascinating aspect of this phylum which I have not heard discussed on your show. This is the apicoplast. As I am sure Dickson is aware some time in the early 1990s a degenerate plastid was discovered in Plasmodium and later discovered in most apicomplexans. Interestingly it was also noted that Cryptosporidium lacked this organelle and present evidence indicates that gregarines (another type of apicomplexan) also lack a plastid. The presence of this plastid is interesting for many reasons. Primarily this organelle may provide drug targets that would not interfere with host biology (due to the cyanobacterial origin of plastid). However what I find most fascinating is what this implies from an evolutionary perspective, that modern day bloody parasites like Plasmodium have an algal/photosynthetic ancestry. Talk about wild evolution! This has been exemplified by a discovery in 2008 of Chromera velia, a photosynthetic alga that is close phylogenetically to the apicomplexa. Evolutionary implications of this plastid are indeed fascinating from both the perspective of horizontal gene transfer as well as the evolution of the relationship between these parasites and their hosts. These relationship are ancient, indeed! These discusisons tend to stray from topics regarding virulence however I feel your listeners would enjoy hearing something about the evolutionary history which developed these truly chimeric yet single-celled critters!
Keep up the good work


Carolyn writes:

Dear Vincent and Dick,
I am really enjoying your podcasts on parasites. I took special note of the one you did on cryptosporidium.

I am a 52 year old beginning backpacker. In doing the research on water purification, I found that giardia and crypto were the two that came up the most. Since I would prefer not to use a mechanical filter and don't mind the taste of chlorine, I want to use a Miox system. (a super-chlorination system using table salt and a battery) The instructions say that it kills giardia within 30 minutes, but it takes 4 hours to kill crypto.

In listening to the podcast, I found that every time it looked like some questions might get answered, the point of the topic shifted to something else.

Here are the conflicts I have:
When I hiked Pikes Peak, the Barr Camp personnel said they only knew about protecting against giardia. Is crypto not something to really worry about? Or is it really everywhere?

You mentioned immunity. If a person is immune, does that mean they won't have symptom? Symptoms are less? I drank out of a lot of creeks and even ditches when I was a kid. Am I immune?

You said that chlorine won't kill it. Will Miox solution kill it in 4 hours, or are the instructions wrong? (The army uses miox)

I REALLY don't want to get sick, but I can't lug around gallons of water everytime.


Sam writes:

What about this for a catch line:

Another twip is hosted.

Another twip is vectored.

Another twip is spiral.

Jesper writes:

All in the Mind, a great radio show from Radio National Australia mainly about things pertaining to the brain, did a show about
parasites and their effect on populations. You'll find it on
including a transcipt.

One comment references RadioLab, which I must assume is the one where Prof Despommier was featured.

All the best,


Felix writes:

Hi Prof,

I don't think in your program on Crypto that you actually said by what mechanism it causes diarrhoea.
Whereas you have given similar explanations for other organisms.


Atila writes:

Dear Twipers and Twivers,

After listening to all TWiPs (although I will listen twip 19 in some minutes) I have noticed many readers send suggestions of parasites that manipulate hosts behavior, such as Cordyceps fungus. So, I wanted to make my contribution too, and add to the discussion of modifying mosquitoes to bite less and decrease malaria transmission.

The problem I see in this approach is that the plasmodium already does it! Plasmodium is able to make the infected mosquito bite more frequently, thus increasing its transmission:

Koella, J. C. (2005). Malaria as a manipulator. Behavioural Processes, 68, 271-273. doi: 10.1016/j.beproc.2004.10.004.

Also, it is not only the mosquito that plasmodium can modify. It makes infected people more attractive to mosquitoes:

Lacroix, R., Mukabana, W. R., Gouagna, L. C., & Koella, J. C. (2005). Malaria infection increases attractiveness of humans to mosquitoes.PLoS biology, 3(9), e298. Public Library of Science. doi: 10.1371/journal.pbio.0030298.

As a regular TWiV listener (and a big fan) I like the differences between the two podcasts. Professor Despommier's impeccable narration (I liked this letter) makes parastism really interesting. I had a terrible impression of parasitism in college, it is a big topic of biology in Brazil, since there where many parasitic diseases here not so long ago, and some parts of the country still have it, and the lectures were all focused on long life cycles a lots of different names.
Only after reading the histories behind the diseases, the patients and the discoveries, as well as learning the host-parasite interactions I started to like this topic. Carl Zimmer's texts had a big role in this change and I am very fortunate to hear someone with so much experience and personal history as Dick Despommier in TWiP. Specially now that he is a busy popstar and bestseller writer.

Long and prosper success to TWiP,


p.s. I have great expectations for the guests you may invite, given the quality of TWiP and the guests of TWiV.

TWiP 19 Letters

Brian writes:

Hi, Vincent and Dick,

Love your podcast, and did not drink from the streams in Switzerland, because of the cows at all altitudes, even though your Giardia-cast only came up upon my return. I've attached a picture (jpg) of the Swiss version of vertical farming. This is far from the most precipitous slope we found cows on, having only a 20 percent or so grade, but its the only one we took a picture of...When the angle gets over 50 degrees or so, it's mostly sheep and goats, but some cows even then. If the cow-tipping phenomenon ever got started over here, the cows would probably "tip" down a few thousand feet.


Matthew writes:


I just finished listening to Episode 17 and your note about the Israeli study showing that asymptomatic Giardiasis can result in higher growth rates in children than the control got me thinking. Forgive me if this is something that you have already covered, but couldn't a parasitic species (not necessarily Giardia in this case) eventually evolve into a symbiont and visa versa? Do we have any examples of this? Although we have bacterial symbionts in the gut tract, do humans carry any eukaryotic symbionts? Just curious.

Beyond that, I wanted to thank you for the free education that I've been getting through TWIP. As a layperson, I find it easy to follow along with your talks. The biology can be complex, there seems to be a great deal of intuition behind it as well.

Just for your own information, I found TWIP around episode 2 or 3 through I-Tunes. I was looking for a new science podcast and found TWIP pretty easily. I listen to each new TWIP while walking to from work and I've been trying to amuse my Facebook friends with anecdotes from podcast, (with mixed results). What can I say, living here in Washington D.C. it's wonderful to listen to a couple of guys talk humbly and rationally about things that they know and love. Anyway keep up the great work and best of luck.

Washington D.C.

P.S. My wife and I did a week in the Florida Keys this summer and I had Hogfish for the first time in my life. It was delicious!

Greg writes:

Dear Drs. Vincent Racaniello and Dick Despommier;

I am a student research assistant here at FGCU's virology research lab. I am hoping to get my degree and study clinical pathology and have recently begun listening to your TWiP podcast in addition to the TWiV podcasts. The question I have for you both relates to a comment made on TWiP that persons with Crohn's disease that become infected with Trichinella seem to get rid of the disease. Now, are there any mammalian viruses that can infect a parasite such as Trichinella while they are inside the host, and how do the mechanisms work that allow the immune system to adjust from auto-immune dysfunction of an IBD (such as Crohn's) to fighting an intracellular
parasite as the cure for that auto-immune disorder.

Florida Gulf Coast University

Reynard writes:


I have been listening to TWiP since the second episode and let me join the crowd of listeners who are similarly infected by your program and want more of it! If I had it my way TWiP would be a daily program. Your conversational style is didactic yet natural and I wish that many more scientists would follow your lead in their respective fields. What used to be a science of passing interest to me is now a source of frequent awe. I hope to return to University soon to study microbiology and TWiP helped to make that an easy choice. I thank you both for the time and effort to bring this show together. Keep up the great work!


Amy writes:

Hi doctors,

This break is too long.
I miss you guys!
Keep up the great episodes.
I love TWiV & TWiP!
Very interesting and very well presented. Your the best podcast I have ever had the pleasure to listen & learn.
Thanks again for all the work you do getting the Info to the public. I am so glad to hear that you really do enjoy putting together these podcast. Thanks again for feeding my brain.

Your fan and CA Vermiculturest AKA Microbe Farmer

Sophie writes:

Dear twiv and twip hosts - as usually I can't keep to one subject :)

I have a couple of questions and some answers for twip - leishmania.

First of all, Dick said that there was new and old world leishmania, but as i heard it, the "outbreak" in the US was imported from Europe, so is the Leishmania in the US of the old world strain. By the way - dogs with leishmania only get treated if they're symptomatic, as the medicine is quite hard on them.

There is something I don't really understand, it might just be me, but wouldn't it be better to have mosquitoes that vaccinates you against one thing and still can transmit the other, than having wild-type that doesn't do us any good - wouldn't there be ruffly the same amount of mosquitoes no matter what?

Jim writes:

For TWIP comment (link). Do you think this will be a very long lasting solution?

John writes:

Dear Dr's, Candidates, and Notable Notables,

Hello my name is John from Rhode Island. I'm a graduate student studying business with a background in economics. However, I find science, medicine and skepticism related podcasts to be the most interesting. I just wanted to comment that I found the podcasts, both TWIV and TWIP, to be very interesting. I think I first found TWIP through related podcasts from Dr. Crislip's Persiflager's Pusscast, another excellent podcaster. Anyway, congrats on the good shows, keep them coming and you do have non-scientifically trained listeners out there (but I suspect we're all science nerds anyway).



TWiP 18 Letters

Avery writes:

Hello Doctors,

In episode #1 of Twip Dr. Despommier mentioned the gap between protozoans and nematodes with respect parasitism. I wonder if this claim takes into account the fish parasite Buddenbrockia plumatellae. Because its body is vermiform it was long thought to be a worm, but my understanding is that recent DNA analysis revieils it to be of the class cnidarian like jellyfish, hydra and sea anemones. This means, again by my understanding, that it is a parasite which falls between the aforementioned gap.

I am not a scientist and I might be misinterpreting the data. I discovered Buddenbrockia plumatellae while randomly following links on the Tree of Life Web Project. After reading the entry on this little guy I was struck by the idea that the body and behavior of a worm evolved in parallel in two separate organisms; I was also struck by the more general and somewhat eerie feeling that natural forms conceal more diversity and history than we are always able to know. I have read for instance that the complete extinction of one species or another of butterfly may have been obscured by the relative health of a neighboring species of butterfly with identical markings.

Anyway. Thanks you so much for your podcast and for giving interested people like myself an opportunity to learn from experts.


Brent writes:

Hello TWIP!

I love the podcast!! I just read an article in the July/August issue of Mental Floss Magazine. The article talked about the research into a possible Malaria vaccine. The article focused on the research being done by Dr. Stephen Hoffman but it said work is also being do by others. Can you talk about the prospect of a vaccine for a parasite.


Washington, DC

Jim writes:

Faboo podcasts chaps ........twiv and twip.

Just listenening to twip no. 3 though and heard Dick say Aldous was Darwin's bulldog. He was the descendant of T HHuxley of course.
I Guess someone already corrected you , but heck............... glad to be of service.... I dunno much else mind you.

Mucho thanks.


Valentine writes:

Hello Sirs,
I am writing for a couple of reasons.

First is to tell you I really like both the podcasts.

I'm just an ordinary nobody with only what science I picked up in high school and threw reading. I have picked up a lot more thanks to you. You make it very interesting even for those of us not in the "know".
Second and the reason for the subject line. Please please please let people know they can also get your podcast with a podcatcher. I don't use itunes I use Juice podcatcher. I found your podcasts on feedburner and I believe you would get more listeners if they realized they can find and download your podcast with a podcatcher.

By the by Dixson (hope I spelled that correctly) has a great voice.


Peter writes:


I know this is not part of the "Protozoic Parasites" focus of the show, but it is an amazing example of a parasite altering the behaviour of it's host:



Felix writes:

Dear Doctors,

having listened to your 3 discussions on Malaria I decided to get a
book on the subject.

Heading on over to Amazon, I couldn't see much that caught my eye except:

Mosquito: The Story of Man's Deadliest Foe by Michael D'Antonio, Dr
Andrew Spielman 2002
(for £4)

However, in the latest episode of TWIP you recommended:

The Fever by Sonia Shah (for £13)

which you say you have not yet read.

And then, following your advice, I headed on over to Meet the
Scientist to listen to the episode with Prof. Irwin Sherman, only to
find that he has written a book on Malaria (among others):

The Elusive Malaria Vaccine: Miracle or Mirage by Irwin W. Sherman
(for £28)

He also seems to have a new book out on the 1st Oct:

Magic Bullets to Conquer Malaria by Irwin W. Sherman (for £28)

So my request to Prof Despommier would be, once you have read Sonia
Shah's book (if you intend to), please advise your loyal listeners
which one book on Malaria out of the many available you would

I am looking forward to your forthcoming episode on Malaria with Dr
Knirsch to learn even more.

You often say that such-and-such a friend or acquaintance of yours
would be a great guest - but they don't materialise!
I DON'T CARE you 2 guys together are all I need.

Live long and podcast!


Arsen writes:


You asked us to design an experiment to confirm, if toxoplasmosis indeed increases the probability of mice being eaten in the wild. The constraint was that we shouldn't influence the behavior of the mice in any way.
What about if we measure cats instead?

We could take 2 remote islands. On one there would be no mice or cats infected with toxoplasmosis, on the other toxoplasmosis would be prevalent. Both islands would be habitable for mice, and would not have any natural predators for them (except cats, which we also would introduce). Also, besides mice, both islands wouldn't have any food for cats.

What we would measure would be the amount of fat the cats would have accumulated during the summer. If indeed toxoplasmosis increases the probability of mice being eaten, we should be able to detect statistically significant difference in the mass of fat, accumulated by cats on both islands.


Akhil writes:

Hello Vince and Dick...

You guys are the foundation of my razor sharp knowledge on Parasitism and Viruses in my class. I hated it but I gave away the secret to my knowledge to other students in the class they are all subscribers now.

I am originally from India so I would love to tell you guys how to say Kala Azar (Black Fever). I would love to tell Dr. Despommier as his narration is impeccable and our king deserves every jewel in his crown.

It is said Kah-La like La La not Kay-la like Layla... Kay La means Banana in India.

Azar is said like Uh-Zur.... Uh from Uh-Oh and Zur from Leisure, Teaser, Seizure.

everybody writes quite formal emails... so i should say, you guys are totally RAD.

Hey Prof. Vince I am not smart enough to enter contests now but I will compete for Drobo by the time they have a neural chip.
Dr. Vince if possible please explain us any Virus Origin Hypothesis on Twiv.. sorry if I missed them on any podcast.


Raphael writes:

Good day, Drs. Vincent and Dickson!

Just sharing you a link through email from Symposier about Trypanosomiasis/Chagas' Disease, a good historical background as well as images and videos of actual parasite invasion of cells.


Lars writes:

Hello Twip team,

Did you hear about the study that showed that Plasmodium falciparum
had jumped not too long ago from Gorillas to the human race.

Keep up the good work with the TWIV and TWIP podcasts!
As a Ph.D. student in plant/agricultural sciences I dont have much use
of the podcast content for my work but I really like to
listen to TWIP and TWIV while preparing samples and when i have some
spare time.

Greetings from Germany


Richard writes:

Dear Dickson and Vincent,

While listening to TWIP episode 15 "Tryp the light fantastic" Dickson referred to Rhodesia as being named after the Dutchman Rhodes.

Cecil Rhodes was certainly not Dutch. See if you can guess where he was from based on the following quotation, courtesy of wikipedia;

"Remember that you are an Englishman, and have consequently won first prize in the lottery of life."

Thank you for the wonderful TWIP episodes so far. Our research group recently started a programme looking at the impact of IRS on malaria in an area around Lake Victoria. Its a 21h drive from where I am based and we got through many, many episodes of TWIP and TWIV so far during the drive! Makes the time fly by.

Long live TWIP and TWIV!


TWiP 17 Letters

Bjorn writes:

Hi Vincent and Dickson,

I want to correct a statement you made in the trypanosomes episode. Apolipoprotein L-I in human blood kills only the subspecies Trypanosoma brucei brucei, whereas the East African subspecies Trypanosoma brucei rhodesiense and the West African subspecies Trypanosoma brucei gambiense have evolved mechanisms to escape the lytic Apolipoprotein. This means human infections with these two forms, if untreated, are always lethal. The good news is that through efforts spearheaded by the WHO the number of estimated infected persons has been reduced to about 60.000 per year [WHO 2006].

Thanks for your edutainment-podcasts,

Björn from Germany

Thomas writes:

Greetings Professors:

I originally got hooked on your show after discovering the treasures that awaited me in iTunes Podcasts, specifically Quackcast {Dr. Crislip whose droll sense of humor is quite like mine]. Eventually I discovered TWIP then as an added prize, TWIV. Since I am 71, I have seen the whole practice and concept of medicine change radically, as has almost everything else, in my lifetime. I always had an interest in medicine and back in the '70s even did medical histories for a "Free Clinic" run by volunteers varying in education from MDs to interested amateurs, like myself.

I have been watching the TV show that Prof. Despommier works for as a consultant [Monsters Inside Me]. Unfortunately the show reminds me all too often how so many of the people featured could have saved themselves a lot of time and discomfort if the physicians they dealt with had taken the time to take a medical history at the outset. In fact, I think the first question any doctor should ask is "Have you traveled to a foreign country, and if yes, when?" Also while it may seem wise when you hear hoofbeats to think horses, not zebras, as someone who has visited Tanzania, I always consider zebras as well as horses.

Anyway, your show has allowed me through listening to the same shows many times, to absorb some of the new concepts current in medicine today. Even though my mind is a poor shadow of what it was in my youth, I am still able to learn, just at a slower pace. I recently considered purchasing Mandell's two volume tome on Infectious Diseases. I put it in my my Amazon "shopping cart" where it sat while I gave some serious thought to whether I wanted to spend almost $350 to purchase it. I finally decided not to but found to my ultimate pleasure, that an Amazon "shopping cart" that has something in it and isn't acted upon in a reasonable time activates itself. I am glad it did as I am really enjoying reading it on-line and in the printed version. On-line access and "search" is an added feature if you purchase the book[s]. I think back to when I was a youth and there was a book Dickson might recall as he is advanced enough in years, titled "Not As A Stranger", an interesting novel that fascinated me as it was centered on the education that lead to acquiring an MD degree. How things have changed :-) I had an older copy of Mandell's [sic?] book on Infectious Disease dating back to the early 1980's and it amazes me how so completely a different approach their is to infectious diseases due to our current knowledge and emphasis on both evolution and genetics.

Anyway, continue with the great shows and realize your audience may extend beyond the boundaries of listeners you might have thought interested in it.

Thomas (

Dan writes:

Dear Vincent and Dick,

First, let me say that your podcast is fantastic, very informative, and enjoyable to listen to in the mornings during my commute. The reason I am contacting you both is actually less about the podcast itself, and more in regards to the subject matter, or, how one gets into it. I recently finished my undergraduate degree and am interested in going off to public health school in a few years. I've been interested in the infectious disease aspect of community/international health for a while now, and most of my undergraduate degree focused on medical anthropology and infectious diseases (basic biostatistics, ecology courses, a survey of infectious disease biology, and a class on disease ecology). I've been thinking about the graduate school path, and I know that the spectrum of eukaryotic parasites, particularly the protozoan-caused diseases, are what I would like to focus on. However, as most masters programs don't seem to have a particular "parasitology" concentration (with the exception of Tulane's MSPH...), I was curious what advice you two may have for someone interested in entering the field. Go into epidemiology? Environmental health? Population biology?

Any advice will be much appreciated! Thank you for your time,


Scotty wrote:

Thought you guys might get a kick out of this:

Why Captain Higgins is my favorite parasitic flatworm

Dicrocoelium dendriticum, I salute you.


TWiP 16 Letters

Tom writes:

Dear Mr. Racaniello and Dick,

Thanks for TWIV and TWIP as both are great shows. Such a give and take of history, information and humor. Stumbled across TWIP several weeks ago and gave it a try. My only disappointment was there were not many podcasts. Thought I would try TWIV and to my delight found that TWIV was not a new podcast so there were many hours available for my listening enjoyment. No pressure here but if you can more than once a month would be great.

No disrespect to Dick in my greeting but I feel a certain familiarity towards Dick, so the greating Mr. Racaniello and Dick, as I happened to pick up some prime specimens of what he spent much of his academic life studying. Some ten year back I spent a bit of time bumming around Venezuela and as they say the rest is history. It was fun listening to the two of you cover this topic in episodes three and four.

Thanks for sharing your insight and humor with the rest of us.

orcas island, WA

Jim writes:

Vince and Dick,

An hour-long broadcast about famous tumors includes a discussion of the Tasmanian Devil tumors during which the question is asked whether these communicable tumors can be considered a parasite. What do you guys think? That segment is covered in about the first 15 mins. of the program.

The HeLa cells are also nicely discussed and linked to polio research.... The Radio Lab guys do good work, just like you dudes!

Got ten buckets of great peaches off one of our two peach trees, finally, after ten years of trial-and-error; my lab.... Had to use malathion at the end and regret that, but the stuff sure works well.

Smithfield, VA

Heather writes:

Dear TWiP,

I am a 3rd year medical student here at Columbia. Dr. Despommier actually interviewed me when I applied and had a lot to do with my decision to choose this school, and then he told us about TWiV during a Parasitology small group session last fall and had a lot to do with my listening to this show when I should be studying for exams!

I thought you would get a few seconds of amusement from a medical student's interpretation of one of Dr. Despommier's lectures. Please see the attached PDF with a portion of my notes from the first Parasitology lecture he gave last fall.



Marshall writes:

I just wanted to make sure you saw this:

Apparently a mosquito has been genetically altered to be resistant to malaria. I haven't had a chance to read the PLoS article, but maybe you'll find this interesting.

TWiP 15 Letters

Eric writes:

Doctors Racaniello and Despomier,

My name is Eric and I am an undergraduate student at DePauw University, a small liberal arts institution in Greencastle Indiana. I am part of a science research program but because I don't have the capacity to conduct publication quality research with the resources at DePauw I have had to look elsewhere to get my laboratory fix. I spent last summer at the University of Notre Dame conducting informatics in a Toxoplasma lab with Dr. Kristin Hager and most recently took a semester off campus to spend 40 hours a week in the lab of Dr. David Roos at the University of Pennsylvania. My research thus far has centered around functional and comparative genomics in the Apicomplexa but I am fascinated by all things microbial. Now that I have left UPenn I really miss the research lectures and the conversations with people in the lab. TWiV and TWiP help fill this void as big names in research don't come to speak at little liberal arts schools.

Anyway I have a hypothetical procedure for tracking mice and monitoring behavior in infected vs. non infected mice. There are many different strains of Toxoplasma gondii but traditionally the Toxo community into 3 groups: Type I, Type II, and Type III. I'm not sure which type of strains are most likely to show up in wild mice but it would be interesting to see not only if infection changes behavior but if the behavior is strain specific. So first I would set up traps and capture wild mice. I would test them for the presence of Toxo as well as screen the positive mice for strain type. The different strains are well characterized ( and we could use PCR and strain specific primers for the characterization.

The key step would be the tracking. One of my best friends is a PhD student in Dr. Giles Duffields lab at the University of Notre Dame. The Duffield lab works with Anopheles gambiae. Without ruining Sam's PhD project I will just say that the lab has developed what is essentially a nano-particle type GPS system. They can tag mosquitoes with the device and then release them into the environment, tracking the mosquitoes movement in real time. The hope is that the tracking will lead to a better understanding of how mosquitoes interact with their environment so that we can control the spread of malaria and other Anopheles vectored diseases. If this chip can be outfitted to a mosquito, I would bet that I could stick it in a mouse without changing mouse behavior.

Once released, all of the mice could be monitored in real time and behavior shifts should appear as changes in movement. It would not be necessary to try and capture any cats or recapture mice to find data because everything would be digitally tracked. This experiment would not help in terms of causation as to why the infection changes behavior but it would be a great indicator as to whether or not there actually was a change in behavior. Causation falls back to microarrays and analysis of Next-Gen sequencing, which I am hoping to dive into in grad school next year.

Without knowing exactly how the tracking particles work I can't outline much more of a procedure but I know the particles exist and the way they will be applied to tropical disease research is pretty amazing.

Keep cranking out TWiP and TWiV. I find them at the perfect level of comprehension for an undergraduate lab rat such as myself and I can't wait to see which parasite is next.


Terry writes:

Hello Vincent & Dickson

I absolutely love your podcasts and share both TWIP and TWIV with my microbiology students, as well as (when appropriate) my Anatomy & Physiology students.

I have two questions for Dickson.

1) In your ongoing malaria discussions, could you elaborate on the relationship between malaria and sickle cell (and other such interrelationships with malaria). I discuss this in both microbiology and during the blood lectures of A&P. (currently only 15 minutes through episode#10, forgive me if this is covered already).

2) Your stories of science history spark tales I heard back in the late 70's and early 80's of my undergraduate days and into grad school. I had some amazingly well read professors during my time at Midwestern State and at Univ. of North Texas. Those historical tales always thrilled me, and I love bringing those to life in my own lectures when I can. Do you have any recommendations for books of science history, especially those that are as intriguing as some of the tales you share on TWIP?

Many thanks - and please, keep up the good work!


Jim writes:


Great TWIP 8, of course!

Additional listening about the vaccine for malaria in episode 49 of Meet The Scientists by Dr Irwin Sherman at: It's about 25 mins long.


Just saw reference to biohacking and saw this site, and another, , that indicate a possible trend.

Smithfield, VA

Jim writes:

Vince and Dick,

I heard an audio segment about tapeworm infection via cats and dogs that lead to liver cysts and death that surprised me. I thought tapeworms were confined to the intestines. So I googled the topic and see, as in this link that there are several species, and primary or intermediary phases, and multi-organ infection in some cases. Please consider this topic for discussion in a future episode of This Week in Parasitology. The linked article was authored by a couple folks in your neck of the woods in case they are willing to participate in the discussion.

Smithfield, VA

Jim writes:


Have diagnostic conditions changed for parasitology from this quote in a 10-year old text?

"Diagnostic methods for protozoal diseases have not changed fundamentally for many generations, and the sophisticated devices used for bacterial and viral detection have not yet reached the parasitology laboratory. Cultivation methods for pathogenic protozoa are difficult, and a correct diagnosis often depends on direct observation of tissue specimens together with a sense of intuition and understanding of the patterns of disease..."

p. 487, "Fundamentals of Microbiology" 5th ed, I. Edward Alcamo, Ph.D, c1997

Dr Alcamo was at SUNY when the text was published. Perhaps he would like to comment?

Smithfield, VA

Jim writes:

Sent a reference to it and comment about outhouses on piers over lakes by Scandinavian settlers to
Prairie Home Companion. Expect to hear about it in an upcoming Lake Woebegon segment.

Smithfield, VA

#8 was good, too, but nothing beats your reparte.

Todd writes:

Hi Guys, I heard you on Futures in Biotech and just yesterday decided to download all the Twiv and Twip podcasts and add you to my RSS reader!

I'm not in the medical field, but have an intense interest in science and technology, and I have been impressed with your ability to break the information down for the laypeople in your previous appearances on FIB, so now I'll be getting a regular dose of you directly.

When my fiancee came home last night, I told her about your podcasts, and she told me she had just rec'd and email from a friend with Ulcerative Colitis. This poor woman has suffered terribly with it for years and has found little to control it. In this email she mentioned that she was considering Helminthic Therapy, mentioning also it involved parasites, and my fiancee wondered if I had heard of such a thing. I had not...we discussed therapeutic maggots, a topical use, but I was not aware of anything that would be injected or ingested, so I checked online for the answers and decided I should just ask the experts.

Any information or opinions I could pass onto our friend would be appreciated.

Thanks for your continued great work.

Denver CO

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