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What's gotten into you? In this hour, Radiolab uncovers a world full of parasites.

Could parasites be the shadowy hands that pull the strings of life? We explore nature's moochers, with tales of lethargic farmers, zombie cockroaches, and even mind-controlled humans (kinda, maybe). And we examine claims that some parasites may actually be good for you.


Dickson Despommier, Dr. Robert Sapolsky, Fuller Torrey, Pat Walters and Carl Zimmer

In Defense of Cheats

Carl Zimmer plays defense lawyer, trying to exonerate parasites for their wrongs, while Jad and Robert argue in defense of the victims. Our producer Lulu Miller comes in to moderate a lightning round of: "Parasites: are they evil, or are they awesome?" The parasites in question are the ...

Comments [20]

Sculptors of Monumental Narrative

Dickson Despommier tells us the story of how the insatiable millionaire John D. Rockefeller turned an eye to the untapped market of the American South and ended up eradicating the hookworm (and, in the process, a number of other awful afflictions) with an ingenious contraption. Then Pat Walters ...

Comments [40]

The Scratch

When executive producer Ellen Horne was expecting a baby, she really had no particular intention of becoming a self-made expert on a parasite named Toxoplasma gondii. Robert Sapolsky explains to us why Ellen had reason to worry when she was scratched by her cat, and he traces the unlikely ...

Comments [34]

Comments [153]


My biology teacher is making the class listen to this for homework and write 1-2 pages explaining if parasites are good or bad, which Darwin principle is being used, and give evidence from this 1 hour podcast which has me figuring out,how am I going to finish this before I fall asleep? I just started this not long ago, maybe at 9:30 pm. Not to mention that this is interesting but where are the bot flies? Just like John asked.

Feb. 15 2018 12:40 AM
thomas samoth from Cherokee Nation Homeland

I saw little to no system analysis such as hookworms effect the enzyme cascade which if out balance plays a role if not the source of alleges, asthma, MS, crohn's disorder, foggie brain syndrome, especially first thing in the morning, and low energy syndromes taking the from of several types. hookworms may modulate the human bodies' enzyme which give relief of symptoms of enzyme disorder. if one has foggie brain upon rising then set your alarm device and take 4 good quality enzyme capsules with a 6 oz of water and go back to sleep. if foggy brain is gone several days in a row that is good. For allergies test just start taking enzymes and see what happens. many peoples allergies occur after an accident such as whiplash or broken bones but the time between the incident and allege season is too long to connect the dots except by questioning for the pattern. Some people are as afraid of enzymes as taking a few hookworms and that threshold for action bears this out. Consider, we do not eat fruit and veggies out of the garden and the enzymes in our food have a short half life.

Sep. 05 2016 11:21 AM
Andy from Oregon

This was an interesting episode (if a bit wacky on the sound effects). Seems that parasitism evolved as a survival method that takes advantage of concentrations of resources. Such as the nutrients available in robust insect populations. Presumably parasites are a product of millions of years of trial & error, so some have become highly successful and won't outright kill their host. But apparently they're not all as "refined" (seemingly smart?) as the examples in the story. And if memory serves, heartworm is an example of one that does attack vital organs. So nature contains a range of organisms that have explored just about every avenue of survival and procreation.

Sep. 04 2016 01:55 PM
Kira from Fort collins, CO

I have been battling parasites for 4 years now. It was to the point where I had over 170 symptoms, including dementia, siezures, arthritis, severe nerve pain, bi-polar etc. To anyone out there that has an u diagnosed illness or feels they have been misdiagnosed, please look up the "salt c protocol ", and diatomaceous earth. The combination of these, plus a couple other supplements and medication, has made it possible for me to have a life and sense of self again.

Sep. 01 2016 03:22 PM
lex loeb from pdx, uSA

There is something more to the story. My brother now the head of neurology at the University of Illinois, Chicago is studying a cure for epilepsy caused by tape worms that migrate into people's brains in much of the tropical world. If any influences human behavior directly this all too common form of epilepsy is something to consider in the study of parasites and their hosts behaving differently maybe in the interest of those tape worms. Seems to me tape worms also cause people to eat more and maybe possibly makes them hungry for the types of calories tape worms need to flourish?

Mar. 21 2016 04:20 AM
Edgar D. Havisham from Oviedo

This podcast was very interesting. It explained in vivid detail the life, anatomy, and habits of many different parasites and insects. It went into great detail with cockroaches. The sound effects definitely added a different mood to the podcast and created a for detailed image in my mind. The way that the speakers clearly use technology to their benefit also creates a more enthralling and entering experience that made the hour go by really fast.

Oct. 27 2014 08:55 PM
kevin griffin from Los Angeles

Way to go Radiolab, you really stretched it to breaking point with the Toxoplasma story. A discussion of an idiosyncratic mechanism of parasite reproduction segued fairly quickly into rampant speculation on the loss of control of free will in humans. Although I often enjoy Radiolab, some segments definitely have an aura of "fringe" about them, and there is big tendency to speculate on what either preliminary observations (if true ...), and a failure to indicate that the idea being presented may be quite controversial in the field. I think this segment had about three layers of speculation piled one on top of another. While this may make for good radio, this kind of piece illustrates a lack of critical editorial control. If you are trying to popularize cutting edge science, please don't let the facts get in the way of a good story.

Oct. 12 2014 10:29 PM
Bethy from Richmond, CA USA

I just finished listening to the program--through the parasite part, with Jasper Lawrence. Yes, it made me squirm, but it also made me think of everyone of us who has an auto-immune disease.

We have diseases in which our own bodies are attacking us. I have Diffuse Systemic Scleroderma/Sclerosis, which is a rare form of Scleroderma/Sclerosis that I will die a horrible death from.

Not much is known about the disease, so would it kill me to try some of those hookworms???

Oct. 11 2014 04:57 PM

With rapt attention I listened to your program about parasites.
Though very interesting but I was struck by Jasper Lawrence who went to Cameroon, in West Africa to walk on the stools of the villagers.
Coincidentally, I was talking to a Nurse yesterday, who said she was originally from Uganda, and said Ebola originated in Uganda in the 70s and confined to a small village and the spread was contained and the current spread must have been triggered by researchers, missionaries, NGOs or the Africans themselves travelling from the villages to the cities.
Jasper Lawrence though meant well but the story makes me wonder about how these parasites and viruses get out of confined areas.
Conspiracy theories abound about spread of contagion in Africa, but listening to the Radiolab. today made me realize that some of these theories are not far-fetched.

Oct. 11 2014 02:44 PM
Wetdog from Somewhere else

I love these broadcasts but is it just me or does anyone else feel that every time they hear "This is Liza Fleeshman...." they want to stick a fork in their eye...

Jun. 17 2014 12:25 PM
Jonah Buck

Your podcasts are awesome!!!!!!!!!!!!!!!!

Apr. 01 2014 08:20 PM
F. Malkin

Here's an article about how certain bacteria in the gut can effect psychological behaviors:

Jul. 21 2013 08:04 PM
Ruth from Cincinnati, OH

Listening to the parasite segment about "we're too clean" - I have been spreading this insight to people in my life for a long time. In fact, other than some particular circumstances, I nearly refuse to use the hand sanitizer that has become ubiquitous - don't worry, I do cough/sneeze into my arm, etc. (no sense in spreading extra germs). I don't worry too much about picking up the food I've dropped and eating it - again, not the upside down peanut butter toast. Amazing to learn from this segment that, as I seem to see the incidence of allergies increasing, there may actually be a connection between our germaphobic lifestyle and allergies. It makes so much sense. We are even more connected and dependent on the web of life than we realize - and realizing it is a very good thing all around!

Jul. 20 2013 04:00 PM
April Wolff from Manhattan




Jul. 20 2013 12:53 PM

I am vegetarian so i am a parasite off of vegetables. The only people that arent parasites are the ones that live off fallen fruit and fallen grain. Therefore they arent parasites. I have more of a problem with meat eaters than parasites. I just dont want one in me... but then again i wouldnt want a republican following me a gun hunting me like Trayvon Martin.

Jul. 19 2013 05:00 PM
Alex from Teaneck, NJ

This episode always fascinated me, especially the relationship of parasites to our autoimmune issues.

Looks like the idea is hitting mainstream :

May. 06 2013 08:37 AM
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Mar. 06 2013 11:18 PM

A lot of songs were mentioned but I don't think this one was covered yet. Does anyone know the artist or name of the song at 30:50?

Oct. 30 2012 01:40 PM
Chris from Currie, MN

Going back through old podcasts that I haven't heard and came across this gem. An absolutely fascinating program. Many thanks, guys!

Oct. 09 2012 10:31 AM
seif from Madrid, Spain

I am very surprised how parasites could have such impact on a human's body and the fact they could stay in a person's body for such a long time without the person themselves noticing. It just amuses me how such a small thing could be that powerful. Honestly I started the listing to the podcast expecting that I would listen to something boring about parasites which is an unpopular topic with the teens world but actually this podcast opened my mind to this subject and made me interested. This also taught me not to underestimate the small things in life and Nature. I enjoyed listening to the hookworms part :)

Oct. 02 2012 02:26 PM
Monica P.7 from Madrid

1) -Not all parasites are bad for humans, some help cure allergies and asthma.
-Parasites cannot live on their own, they need a host (they are dependent).
-They can cause stomach diseases and mental diseases.
-Hookworms affect the small intestine and the lungs and this makes the person more slow and tired.
-People would not notice that they have parasites living in them.

2) I was surprised when they talked about the Emerald cockroach wasp and how they took control over the cockroaches' body to be able to use it as a host for their larvae. I was also surprised when I heard the story about a man that went to Africa walking barefoot around lakes to find hookworms and get infected just to cure his allergies.

3) If I would choose a parasitic to study, I would definitely chose to know more about the Emerald cockroach wasp. I feel that it would be interesting to know how the wasp knows where on the brain of the cockroach it has to sting. They do not study the brain and are not any like specialists, so how do they know what place they need to sting the cockroach to make them their "slave"?

Sep. 24 2012 05:08 PM
Amalia P.7 from Madrid

A) parasites can cure allergies
B) Scientists believe that early morning sickness is a way of protecting a mother and child from parasitic invasion.
C) 75% of the world’s creatures belong to the parasite family.
D) Humans can be controlled by some parasites called toxoplasma gondii (being attracted to cats).
E) Most parasites start the cycle in one host but want to finish the cycle in a different host.

2) I never knew that hookworms can help cure allergies. The story about the man who went to Africa to catch hookworms to cure his allergies was very fascinating. This man said his whole life was affected because of his allergies. This parasite however helped him and made his life somewhat normal again which is ironic considering it is a PARASITE we are talking about.

3) I would like to know more about the effect of hookworms on allergies. Even if they help with allergies, there has to be a long term effect. Considering hookworms live in the intestines, what harm to they cause? I do know however that they can cause fevers, vomiting, constipation, and chest pain.

Sep. 24 2012 04:28 PM
Paula Redondo period.7 from Madrid

1. While listening to the podcast there were 5 facts that really got my attention about parasites that I did not know before and I think they may be interesting for other people. To start of, I think it’s really interesting how humans generally think that all parasites are bad for you and this is wrong. Some parasites are actually helpful and help humans beat allergies and asthma. Another very surprising fact I found out was that you cant see many parasites inside your body and they are invisible and you’ll never know if they are living inside of you or not, we humans and parasites help each other mutually without us even noticing. I also was very surprised on how many types of parasites there is and how they have adapted to live in many different places, from cockroaches to humans! I also had no idea that some parasites have physical effects on us. According to the podcast, parasites might make us feel very lazy slow, it is like they take out our energy. Finally the fifth most shocking thing I heard in the video was how some parasites have complex ways of living and attacking its host, like for example the parasite that injects a type of drug into the cockroach brain so it is able to go live inside of it.

2. One of the stories that got me very surprised was the one about how parasites use the ants to get to other bigger animals like the birds. I think it is really interesting how parasites use techniques to change hosts. They first make the ant look different by making their butt be red and stick out so it is different from all other ants. The parasites know that the bird is going to go eat the one with the red butt. I thought it was very interesting how they are actually very intelligent and are using both the ant and bird as “plane tickets” as explained in the podcast. The only way to reproduce is inside the bird and what way is better to spread your specie than by laying your eggs on birds excrement that is going to lie anywhere. They are much more “advanced” than I thought they were.

3. In overall I would like to learn more about hookworms and how exactly they are beneficial for humans. I really didn’t know that this parasite specie could cure us from some allergies and asthmas. I would like to understand how they can be so harmful and beneficial at the same time, and why does this happen. I think hookworms are one of the most complex types of parasites and I would like to learn more about them, maybe in the future scientists find out more uses they might have for the health of a human.

Sep. 24 2012 03:44 PM
Cecilia from P.7 Madrid

1) While listening to this show 5 facts really struck me and gave me the impulse of wanting to share this information with someone else. The five facts were the following: hookworms can cure allergies, cats have toxoplasma which attracts you to them, because we are too clean and have a good hygiene we do not have as many parasites in our body as we should have, hook worms can cure allergies and finally cats carry parasites that are not good for human therefore humans should be careful when scratched by them.

2)My favorite story about parasites was the one about Rockefeller's demand on discovering the reason why Southerners were physically slow. I find it incredible how sociologists and scientists came up with the outhouse to prevent parasites from crawling four feet by digging under ground. As a result Southern workers' anemia was gone and the parasites were kept under ground.

3)If I could I would like to learn more about the wasps that manipulate cockroaches and make them go inside a hole, lay their eggs inside the cockroach and make the cockroach serve as food for the larvae. I want to know more about the liquid the wasps inject into the insect's brain and how it affects the cockroach and in what part of the brain the wasp injects the liquid.

Sep. 24 2012 03:14 PM
Charles E7 from Madrid

A) Some parasites may get lay their larvae in some insects so that whenever those larvae mature and become other insects they automatically feed of that other insect.
B) There are parasites that are able to in some way inject a fluid into another organism’s brain and it is able to make the organism its slave in a way.
C) Humans think that parasites are always a bad thing but there are many parasites that are beneficial for humans to have, like the hookworm. It is able to stop allergies or asthma.
D) We can be controlled by some parasites called toxoplasma gondii. This is a parasite that in a way “pulls from our strings” and is able to change the person we are, our preferences etc.
E) There are some parasites that live in our body that help us in some ways because we help them survive.

2) What was new and surprising to me was the fact that the hookworms were able to prevent such things. I found the story of the man who went to Africa and walk barefoot around lakes only to get infected very interesting. The fact that the man’s problems with asthma and allergies got cured thanks to a parasite was very unexpected. It is basically like a cure for these handicaps.

3) If I could study one of the issues more deeply it would be the one on the toxoplasma gondii found in a cat’s feces. I found it interesting how it could in a way change one’s lifestyle or cause defects to a baby. I wonder up to what extent it can do these things.

Sep. 24 2012 01:50 PM
Vera A7 from Madrid

1. Parasites can sometimes be beneficial. They can help you get rid of allergies.
2. They cannot live on their own. They need a host where they can obtain food in order to survive.
3. Sometimes parasites can go unnoticed. They can live in humans without the person knowing.
4. Some parasites like the blood flukes can live inside the human body for more than forty years. They are monogamous and they keep producing eggs, so that is why humans get sick.
5. Parasites like hookworms can cause a person to become slow, lazy and tired since they can affect a persons guts.

The most surprising information that I learned relates to the parasitic wasps. It fascinated me to learn that they can sting a cockroach and paralyze it. After that, they sting them once again in special part of a brain that that allows the cockroach to wake up again. However, they cannot control their own body. Somehow, the wasp becomes its “master” and take it wherever he wants to. Then the wasp lays its eggs in the underside of the cockroach and the new borns have to drill their way up; they eat their way up.

I would like to learn more about hookworms. They seem very interesting and somehow beneficial. Even though they can also cause amnesia and other problems in the human system, they can also be very helpful. They can help get rid of allergies and if you have a hookworm, there a fifty percent less of having asthma. They can help maintain a body’s internal parts controlled and calm. I definitely think that if scientists or researches investigated further on the subject, we could learn how to take advantage of the hookworms without risking getting amnesia.

Sep. 24 2012 01:46 PM
Brittany P.7 from Madrid

1. Parasites can live in humans, without them knowing. They are practically invisible.
2. Parasites are not independent, meaning that they need a host to live.
3. The parasites can invade other parts of the body, not only the stomach.
4. Parasites make people slow, lazy, and tired.
5. Parasites lay eggs inside of their hosts, living off of their host and sometimes even killing it.

2. Something that was new and surprising to me was the fact that the parasites can invade other parts of the body, and not only the stomach. Also, that the bloodflukes were very interesting to listen to. The fact that the can turn the hosts skin into a butter like substance and then move around in the circulatory system.

3. If I had to pick a parasite to study, I would pick either the bloodflukes, or the parasitic wasps. I think that both of these parasites are intriguing and that learning more about them would be a great idea! They are the two that caught my eye and I really enjoyed learning about them.

Sep. 24 2012 12:23 PM
Marcos C7 from Madrid

1. A parasite is an organism that depends on another organism for various reasons. Tapeworms could live in humans or animals and feed themselves with the nutrients by living in their digestive system.
2. Parasites can live in humans with the humans having no clue as they are basically invisible.
3. Parasites can cause many diseases and not only stomachal diseases but also mental diseases as they can also infiltrate the brain of any human.
4. Hookworms can make people slow, lazy and tired as they affect the small intestine and lungs.
5. Not all parasites are bad. Asthma is 50% less likely to happen to a person in a person that has a hookworm. Hookworms could be a cure for people with asthma or allergies so it is very asked for.

I was very surprised that the bloodfluke which are located in lakes (mainly Africa), get into the human body through the ankles by creating an enzyme and then turn a little bit of skin into "butter" in order to surf the humans circulatory blood system. By doing this they find a mate of another gender in order to mate. The males feed the female for a very long time. This bloodflukes could make any human very sick as long as the bloodflukes keep on mating.

If I could chose a parasite to study I would very interested on hookworms and their various effects. Hookworms can have both positive and negative effects as parasites. In a negative aspect, they can affect humans as they can affect intestines and lungs and can even cause death. In a positive aspect, hookworms can remove allergies and prevent asthma which makes hookworms very interesting as they are two faced. They can both help and affect which makes hookworms much more interesting than other parasites.

Sep. 23 2012 06:22 PM
Carmen P7

1. Parasites could be living in your gut without you seeing or noticing them.
2. Parasites have gained the ability to live inside many different species.
3. Parasites are not independent, because they need to feed and live inside another creature to survive.
4. Parasites lay eggs inside another animal where they hatch and then the parasite lives off that organism (sometimes even killing it).
5. Doctors could uncover blood fluids in people's blood many years after getting the parasites, meaning that people may not realize that they are living inside of them.

I was surprised that there were more than 25,000 species of parasitic wasps. I was also surprised that the wasp would sting the cockroach and the cockroach is pretty much a puppet for the wasp. I cannot believe either that a wasp would guide a cockroach. I am also surprised that the wasp was smart enough to leave the cockroach (that is just sitting there)in a cell (built by the wasp so that the cockroach would not die but would not get eaten either) and I feel really sad that the cockroach, after being stung, cannot even lead a normal life until the wasp eggs that were laid in it grow and develop and then it dies.
If you could, what issue, idea, or concept would you like to know more about or study in more detail?
I would definitely want to study the parasitic wasps. I think it is extremely interesting that this wasp can use the cockroach in such way that would benefit it and hurt the cockroach. I would want to study the wasps' venom that has such an effect on the cockroach. I would want to study it just to make sure that this venom cannot be spread to humans or other species, because it is a very scary thought. Also, I would want to make sure that such parasites do not evolve to hurt other species. These properties in venom would be interesting to discover how they work, enough so that the cockroach was "drugged".

Sep. 23 2012 12:14 PM
Dan Plesse from NY

Jumper photo under 1400% magnification turns into CIA Drone with hardened front end NYPD FOIA

Sep. 15 2012 11:30 AM
Thompson Bright from Toolafalls, Mississippi

What's this? It almost seems as if the word "theory" could have more than one definition! Of course, that's impossible. No word has ever had more than one definition, or has changed its meaning depending on context, or has changed in meaning over time. Right?

Aug. 23 2012 02:02 PM
Alex from California

"Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative."

From the Wikipedia page on Theory.

Aug. 22 2012 01:52 PM

I'm high school student and our summer assignment for AP biology was to read Carl Zimmer's "Parasite Rex". Imagine my delight when I heard the author on the radio! Although I'm not done reading it yet, so far the content has been fascinating! Indeed, he makes the case saying that parasites are not degenerates and I believe he proves his point well. Parasites are able to survive in, many times, a variety of different hosts by fooling their immune system; in addition, they have the ability to control their host to an extent, like the cockroach and the wasp example. I was very happy with the subject matter.

Aug. 20 2012 10:57 AM
Barbara Brenner from Ridley Park, PA

I heard the piece on parasites today, and was stunned to hear the ant I saw earlier this summer being described!
I live in the Philadelphia, Pa area and was on the front porch reading when it appeared. It looked absolutely as it was described on Radio Lab today - and it matches the pictures I later found online! Because of the red bulb that stuck straight up on its end, and because it moved so quickly, I didn't know what it was. It ran across the concrete, went down into a crack, came back up, ran a little ways, then back down into the crack. Since I'd never seen its like before, I kept watch, but it didn't re-emerge.
went back into the crack again! I'd never seen its like before and continued to watch for it, but in the concrete, came back out

Aug. 19 2012 08:23 PM

Clowder - REALLY? There is a HUGE difference between a theory and a hypothesis in science - it's the misunderstanding and misuse of these terms in the media (and sadly by lazy scientists) that lead to things like the rebuking of evolution because it's "only a theory." The only disciplines (generally) where theory comes before hypothesis are physics and astronomy because they deal with very big ideas which are often untestable with anything other than mathematical proofs.

Aug. 19 2012 10:39 AM

Elizabeth - while i generally agree with your distinction between 'theory' and 'hypothesis', i think you are really splitting hairs. i checked with and found that the second definition of 'theory' is as follows:
"a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact. Synonyms: idea, notion hypothesis... "

besides, 'theory' is easier to type than 'hypothesis'.

as for the show - i find the theory that toxoplasmosis can influence human behavior quite interesting - i've always been a cat person, and i was 5 years old when i got my first cat. i'd be willing to bet that he had toxo - it was well before vaccinations (not to mention spay/neuter) became SOP.

Aug. 18 2012 07:22 PM
Jean U

I do not appreciate the personification of parasites as "evil". evil is a concept invented by Man to describe Man. any event in nature is an aspect and function of nature and cannot be described as such since any organism in nature makes adaptation to survive...sometimes to kill, and sometimes to run. you can no more blame the lion for taking down an antelope any more than you can laugh at the antelope for being slow. both conditions do not really apply, both species have the necessary resources to catch prey or escape predator. there are billions of cockroaches out there, and thus exist a specie that survives by feeding on it. in fact, we are no more different than the wasp, as we also feed on other animals....and in fact, we could be considered parasites to the planet Earth.

Aug. 18 2012 04:52 PM
Elizabeth Schmitz from Frankfort, KY

Great article. Truly fascinating. However, I was concerned during the last segment when the radio announcer said that "it was only a theory" that toxoplasmosis could be impacting human brain function. A theory has a very well established body of evidence; it takes a LOT of evidence to call something a theory. Evolution and climate change are both theories. Anything that has to be predicated with "it is only a..." should be called a hypothesis. A hypothesis is predicated with some evidence - the researcher thinks, based on some evidence and reasoning, that two things are connected, for example - but there is much less existing research to back it up than would be found with a theory. The confusion between a hypothesis and a theory is responsible for much of the confusion that still exists today about the validity of theories like evolution and climate change. Please be careful about how you use these terms!

Aug. 18 2012 02:19 PM

here's a well-done story about toxoplasmosis from animal planet channel

Feb. 25 2012 06:17 AM
Fia from Sweden

I do not think hookworms work. Very sad about that.

Dec. 07 2011 08:10 AM
Chad from Lund, Sweden

Just found Radiolab... Amazing stuff! I think this was my 6th episode today!

Keep it up! Cheers from Sweden!

Nov. 12 2011 02:08 PM

I just recently discovered Radiolab and I am plowing through all the episodes. Best radio ever. I was wondering what is the southern sounding guitar tune at 31 minutes?

Cheers from Helsinki!

Sep. 05 2011 03:16 PM
timr from Portland, OR

OK, making listening to Radiolab and writing a report or review on it is an OK homework assignment, I suppose, but did you have to tell them to actually post their reviews on-line in the comments!?

Aug. 29 2011 05:50 PM

I can help with one small piece of music, for the curious.
The capper on the end of the first segment, just before the break is from a track by Mice Parade called 'Guitars for plants' from the album Obrigado Saudade

Aug. 22 2011 07:51 PM

anyway i can find out what the music is from all of the episodes? This episode in particular had some very interesting pieces.

Jul. 03 2011 11:10 PM
JT from Salt Lake City, UT

Parasites are totally awesome! I totally wish I could make a living simply by pooping...Just when you think you have heard it all, there comes RadioLab. Thanks for the excellent podcasts!!!!

May. 06 2011 11:32 PM
Nicole from MD

My fav show on Showtime features my all time favorite show on Radio Lab? So excited when my favorite things meet each other! Parasites meet Weeds. Yay Radio Lab!

Apr. 01 2011 11:50 AM
Sam S.

1. By listening to the "parasites" podcasts, I have learned a lot about different species of parasites. One thing I learned is that many parasites have different hosts. One species, called the parasitic wasp, borrows and controls cockroaches while another species, known as the parasitic nematode, uses birds as a host. Other species have a variety of hosts. I wonder why certain parasites need certain hosts. Are there certain nutrients that a certain parasites need in a certain host that cannot be obtained in another host?

2. Another thing I learned about was how the Blood Fluke species of parasites are monogamous. This is interesting to me because I previously believed that all species other than mammals were polygamous. I wonder what the health implications are for most parasites, including this one, in humans. What does a Blood Fluke do to a human?

3. Lastly, I have formed no opinion on whether parasites are "degenerate" or not. I just feel like nature is nature and these parasites have some sort of purpose to natural ecosystems and population control.

Mar. 11 2011 02:14 PM
Dave Pickering from London

Parasitic fungi:

Mar. 04 2011 12:20 PM

I LOVE your show. Just donated. Can't get enough of radio lab as I sit here updating blackboard sites.

Jan. 03 2011 04:34 PM
gabe from los Angeles

Here's an article On a guy who cured his bloody stools with worms

Dec. 09 2010 07:24 PM
Matthew Hudson from London, England

A parasite changes behaviour in it's host.

Puts me in mind of Shakespeare's lines spoken by Cassius to Brutus:

"And since you know you cannot see yourself, so well as by reflection, I, your glass, will modestly discover to yourself,
that of yourself which you yet know not of."

So Cassius is planting the seed of murderous intent in Brutus (i.e. to kill his friend Caesar), using the conceit of a looking glass to suggest it was already there which of course it was not.

Is this trait of human suggestion some kind of parasitism?

Millions of examples mostly trivial, some momentous, must occur every minute around the world and therefore must affect the way we evolve?

Have I just had an interesting thought or am I just talking crap?

Nov. 17 2010 02:42 PM
Jeff from upstate NY

Jason, the Jasper Lawrence story is given in the second half of the second segment, "Sculptors of Monumental Narrative".

I agree: The Jasper Lawrence story is the best part of an incredibly fascinating (if a bit skin-crawly) episode!

Oct. 22 2010 01:18 AM
Jason from NY

What happened to the Jasper Lawrence "segment" and why isn't it referenced on this page? That was the best part of the episode (which is saying a lot).

Oct. 12 2010 08:51 AM
Chris from Philadelphia

I cracked up after listening to the segment about zombie/puppet cockroaches with "Esther" by Phish in the background (a song with a prominently featured puppet). A great deal of thought is put into the production of Radiolab and it is greatly appreciated. Keep up the great work!

Oct. 11 2010 10:38 AM
aaron de Cape Rosier

It is to Melissa that I owe a debt of questionable gratitude for this podcast. From a cocktail soiree to this. There are many times when too much information is too much. I will not discuss barefoot walking around tropical outhouses, Daniel Boone's intestinal tract, or the so-called "beneficial" parasites. And yes, I know that 'they' were here long before Homo Sapiens (me).

Sep. 28 2010 09:42 AM

Haha..just watched "Weeds" s06ep01 and at the end of it Nancy is listening to this very episode of Radiolab while driving and fleeing~ How hilarious!!

Aug. 02 2010 08:49 AM

Haha... I love this episode of Radiolab. I'm just giggling because it looks like a bunch of kids had to do a "book report" on it for a school project (see many of the above comments). ;)

Jul. 29 2010 05:35 PM

I'm listening to this episode again. You guys keep me company while I toil away on HTML coding alone in my office. But enough about me...

Was this the first time Robert had seen "Alien"? His reaction sounds so sincere to the chest-bursting scene, and I love how its edited so that his "oh my god" syncs up with Veronica Cartwright's "Oh my god." Awesome intro to the show.

Jan. 05 2010 04:18 PM

I just started listening to Radiolab and I'm obsessed. Such a great show. The only downside is that I listened to "Parasites" on Thanksgiving morning, then somehow worked it into every conversation I had at a T'Day party that evening. Somehow, people weren't as impressed as I was, hearing about parasites whilst gnawing on a turkey leg.

Dec. 08 2009 08:01 PM

Sorry addresses stripped out of comment. In the site nchealthandhealing under the "Choose a topic to get started" there is a page called hookworms. I have also put it as the website linked to the user name.

Oct. 31 2009 11:49 PM

The first outhouses may have come before the Rockefeller Foundation's health campaigns. For example, Thomas Jefferson built a few at Poplar Forest

This site has some info relating to the health campaigns.

Oct. 31 2009 11:44 PM
Greg Heisenfeldt

Listening to the segment describing a parasite controlling the behavior of rats in order to find its way back into the digestive track of cats got me wondering. Does this indicate that this worm has a sense of "self" and has knowledge of the cycle of predation between cats and rats? How does this microscopic organism know where it needs to be and how to get there? How did this specific knowledge develope?

Oct. 23 2009 06:33 PM
Paul MIller

I am very interested in obtaining hookworms for my mother who has rheumatoid arthritis. I believe since r.a. is an auto immune disease alike to crones disease, the worms might also have a beneficial effect on r.a.. I am wondering how to reach Carl Zimmer and order a few doses of hookworms. My email is If any one can help, that would be great.

Oct. 17 2009 12:13 AM
emma rutstein

i just wrote a huge comment, and i just deleted it. now i have to write it again:

in the first scene, two men and a woman are discussing weather or not parasites are degenerates. one man tells stories of how parasites are well adapted, and the other man mocks him. i thought this was interesing because oragnisms so smal can have such power over much bigger organisms.
next, another man tells a story of how southerners in a certain area were slow and tired and sickly looking. testing was done, and hookworms were found. the people were getting them from walking around barefoot where they had gone to the bathroom. one thing i leared from this was never to walk around barefoot where others have relived themsleves.
next, was a a story of a man with severe alergies. he infected himself with hookworms, and remarkable he got better. they are dangerous though, because they cause pain, digestional problems, and anemia. but on the bright side, they can also cure certain diseases. something i leared from this was that harmfull parasites can also sometimes be increadibly heplfull if you use them in the right way.
following this, there was a man talking about toxoplasm. toxoplasm can olny reproduce in a cat's intestines. the cat will poop out the toxoplasm, and a rat will eat it. the toxoplasm then sort of controlls the rat so that it is "attracted" to cats. the rat gets eaten, and the cat gets toxoplasm. some scientists think the same thing also happens with people, but more in the form of schitzophrenia. what i learned from this is to never come in contact with a liter box, or an infected rat.
i thought these stories were somewhat disurbing, but kind of interesting also.

Oct. 15 2009 05:14 PM
Ben G (2)

1)This WNYC "Radiolab" podcast talked about different species of parasites that can be either good or bad. There was an ongoing debate that parasites are not all bad and that they can be helpful as well. Some of the different types of parasites are; parasitic wasps, hook worms, and blood flukes. First, the parasitic wasp fights with a caterpillar, eventually paralyzing it with a sting that injects "drugs" directly into the brain. The caterpillar, now completely defenseless, is now unmobile and the wasp now lays its eggs inside of the caterpillar. This is obviously one of the bad types of parasites. The eggs are layed there becuase when the larvae break from the eggs they will have a pentiful food supply inside the caterpillar and they will eventually eat there way out and the caterpillar will die. Second, hook worms represent the good side of parasites. These hook worms can be injected into the human body and they can help a person's allergies or asthma. An example of this would be the man they talked with by the name of Jasper. In attempt to get rid of his allergies for the upcoming allergy season, he took a trip to Africa and when he walked places he would walk barefoot. This is because he would have a more likely chance of getting a hook worm in his body. Lastly, the blood fluke is a parasite that "melts" a patch of skin near the ankle and then crawls in and flows through your veins inside of you. Personally, I think that's just plain wrong. It turns out that they eventually find another blood fluke and they mate and curl together while inside your veins. They can also stay inside your body unnoticed for extremely long periods of time.
-I learned that parasites can be good or bad depending on the type.
-I learned that parasites can live inisde you almost invisibly.
-I learned that parasites cause multiple mental disabilties and diseases.
-I learned that some people acutally believe that certain parasites can control your mind.
-I learned that Toxoplasm is common in cats becuase they sometimes eat rats.
3)My overall opinion to the podcast was that it was surprisingly interesting. At first I figured that it would seem that it would just drag on and on and be extremely boring. But the time actually flew by as they talked about a subject for a certain amount of time. Then they progressed to the next as they did before. It's truly extraordinary how these tiny organisms that people think are just here to infect us and make us sick, when there is much more than just that. These parasites can do much more than that and the process in which they do this in is amazing. These organisms can do things that i never thought possible. For example, there is scientific evidence that toxoplasm could cause some emotions to be controlled by certain things. For instance they think that the toxoplasm may attract people to cats more than just liking cats in the first place. This podcast may have been long but the information it contained was well worth it.

Oct. 14 2009 09:45 PM
Josh W (2)

I do not know why that smiley face is on my entry... it is supposed to be #8

Oct. 14 2009 07:35 PM
Josh W (2)

1. The WNYC podcast is an overview on different kinds of parasites, their positive and negative effects, and how they can effect/ “control” human life. The podcast begins with Carl, a science writer, who is an expert on parasites and written many books on the subject. Carl argues that they are not degenerates and gives three examples of different parasites to support his hypothesis. The three examples he gives are; to control a roaches mind, a parasitic nematode which can cleverly get their way into their host to reproduce, a parasitic wasp which can brilliantly perform a “brain surgery” and the blood fluke, which can stay inside their host for years and years. These comments sparked a debate on the podcast, even resulting in the use of a moderator to help settle the debate. Instead of only having a dialog between the panel of people, the producers of the show were able to add sound effects to the show, in order to better explain what occurred in these situations. Another odd event occurred with Jasper. Through his research, he found that people with hook worms had a 50% less chance of getting asthma. Jasper traveled to Africa and walked around latrines barefoot for 2 weeks, hoping to become infected with hook worms. When he returned home during allergy season, his allergies had disappeared. He has now been able to own a business that sells hook worms to people that may be in need of them.

2. What I have learned
1) I’ve learned of the benefits of having some parasites such as the hookworm. Hookworms and other parasites like it have always seemed like a terrible thing to have, but from this podcast i learned of the possible benefits of having hookworms. Hookworms in the proper amount are actually beneficial to people with certain conditions such as severe allergies. I suffer from asthma, so the idea of using a parasite to heal is very interesting to me.
2) In addition, it was interesting to see how the parasite travels or gets to its host. One example of this is how the parasitic wasp takes over the roach’s mind and lays its eggs on it. I find it amazing that a parasite can be inside a host and know which part of the body to get to.
3) Another fact I learned was the mental effects parasites can have. I was awar that parasites could live in some parts of the body, but I never thought that some people have organisms living inside their heads. I also had no idea that parasites could cause mental disorders such as schizophrenia. When I heard this, I wondered if there was a way to remove the parasite from the brain or not.
4) Some scientists believe Toxoplasma can control you and guide my emotions.
5) Parasites attack caterpillars and can grow on them.
6) Hook worms and people have a mutualistic relationship. I always thought that hook worms only harmed the body, but the immune system also is helped out.
7) Toxoplasma can be in cat poop
8) I also learned why the outhouse was created.

3. To be completely honest, I was not looking forward to spending an hour listening to this podcast. I figured that it would be filled with smart people talking about nothing but parasites. I have listened to other podcasts, such as the B.S report by Bill Simmons, who is a writer for ESPN. Despite my low expectations, I enjoyed listening to the podcasts. I liked how the producers were able to add sound effects to the talking, and that helped me pay attention. In addition, some of the individual examples made me realize how amazing these organisms were. For example, I was amazed and scared when I learned about blood flukes and how long they could be in my body. I was also extremely shocked when I heard about how the Toxoplasma may be able to control human thoughts and change the way that we act. I could never even fathom the idea of a creature so small controlling my mind until I listened to this podcast. So although it was a little time consuming, I think this was well worth my time.

Oct. 14 2009 07:34 PM
Shannon B (2)

1. This podcast was devoted to parasites, and if they are good or bad by telling many different stories about parasites good and bad. Carl Zimmer who is a scientific writer who makes an argument that parasites aren’t all bad. He went on to talk about tapeworms, and that how one species can live in you for years and year without their host knowing. Later on in the show a professor from Columbia talked about a species of parasites that would get in to people when they stepped in there own waste when they went the bathroom. These parasites would turn people in to unproductive and lazy people.

2. I have learned very much about all different species of parasites. One of the types of parasites I learned about was the hookworm. This species can either bad or good. They can be very bad because if you do not need them they will enter you when you step into human waste. These parasites can be good because if you have extremely bad allergies then a hookworm can get rid of your allergies. Like Jasper in the podcast he had very bad allergies he went to Africa and purposely got himself infected purposely with hookworm.

3. Before I listened to this podcast I thought that it would be the most disgusting and appalling thing I had ever listened to. After listing to it my view of it changed dramatically, I did not view this podcast a appalling though I still though it was fairly disgusting. The was some of these parasites can enter your body I found very gross, like how some hookworms get into your body. I found it very strange how some parasites can live in your body for many years without you even knowing. Through most of this podcast I though that is was very gross but when they were talking about toxoplasma in cats I was very interested. The way it can travel to a rat and control the way it thinks I found very weird but interesting. Over all I thought this podcast good, but way too long.

Oct. 14 2009 07:00 PM
Jeff K

When Carl was "glowing" talking about blood flukes spooning, there is a beautiful instrumental song playing. What is that song?

Oct. 14 2009 12:14 AM
Emma B (1)

1. On the WNYC podcast about parasites, the gist of most of it is arguing about whether parasites are good or bad. Throughout the podcast various scientists and people with a parasite experience, such as Carl Zimmer and Jasper, come on to tell their views. The hosts of the show mostly think of parasites as bad, but Zimmer and Jasper disagree. Zimmer uses three examples to explain how parasites are good, as well as showing the similarities between humans and parasites. Jasper uses his own real life example and how he was able to utilize parasites to make him healthier. Later in the show, a woman who works with the host talks about her experience with parasites causing her to think that they are bad. The discussion provides the listener with an informational view on both sides of parasites.
2. I have learned many more things than I knew before about parasitic life, and how they are heavily affecting human life. First Carl Zimmer described a parasitic wasp attack on a cockroach. The wasp begins by physically attacking the cockroach, then stinging it. The wasp then inserts drugs into the cockroach brain, and when the cockroach wakes up it is lead around by the wasp by its antenna. Eventually the wasp lays eggs into the belly of the cockroach, and then buries the cockroach in a burrow. The cockroach larvae bite their way out of the cockroach and then the cockroach dies. Blood flukes are another example used by Zimmer. He describes the life cycle of a blood fluke, starting with the secretion of enzymes in a human’s skin, and ending with how blood flukes can live about forty years. I then learned about the importance of sanitation when releasing human waste. In the South, people were going to the bathroom on the ground outdoors. The hookworms in the waste were able to crawl up to four feet after six days, so when humans went to the bathroom, they most likely stepped in their own waste or another humans. This led to multiple diseases, such as Anemia and Cholera. One of the most unusual things I learned was how asthma and allergies could be relieved by hookworms, such as Jasper’s case. After going to Africa with the purpose of exposing himself to and hopefully catching some hookworms, Jasper was successful and is now selling hookworms to help allergies and asthma. Lastly, I learned about Toxoplasma and its connection to cats. This also led to the thought about if toxo could control human emotions.
3. Before watching the podcast, I thought it was going to be very long and too boring. It still was long, but it was much more interesting than I thought it would be. I was amazed and scared when I learned about blood flukes and how long they could be in my body. Jasper’s story seemed strange to me, but I liked the idea about how hook worms were able to be a sort of lullaby to attacker cells and calm the immune system. I would never walk around in human waste like he did, so that was surprising to hear about. For me the most interesting, bizarre and shocking thing for me to hear about was how the toxo might be able to control human thoughts and change us. I thought it was creepy, but I was intrigued as well. Overall, the podcast was good, just too lengthy.

Oct. 13 2009 10:26 PM
Alexa I (1)

Question 1 :
In this Podcast we listened about different species of Parasite. For example we leraned about Parasitic Wasp , Parasitic Nematod , Blood Flouz and,Hook Worm. It told what each Parasite was and an real life example.
Question 2 :
In this Podcast i learned about different Parasites. I learend that Parasites were animals. Not all Parasites are bad. For example the man who inserted hookworm into himself to help with his allergies was a benifcial of the the hookworm.i thought it was extremly weird that anybody would insert parsite into them by stepping in ohter people’s fecies. In Africa the people would go to the bathroom and the hookworm would be in there fecies. It expands at a 4ft radius and then eventually dies off. Resluting in a new system in which they burried their fecies 6ft down so it dies off 2ft below the surface.The Blood Floux were interesting cause they enter into humans and then travel in thier blood.
Question 3 :
This podcast was interesting and really wierd.It was interseting to listen about parasites

Oct. 13 2009 10:08 PM
Alyssa Schmid (1)

The Radiolab podcast spent an episode examining parasites, and attempted to determine whether they are “evil or awesome,” by telling stories of the various lives and uses of parasites. The show began with Carl Zimmer, a scientific writer, who made the argument that parasites are not degenerates, because they can live inside a variety of different species. He also mentioned that while calling parasites dependant, because they need a host, one must also consider that humans are dependant on parasites. He continued to tell stories of the lives of parasites including the parasitic wasp, and parasitic nematode. Later in the show, a parasitologist at Columbia University discussed the feats of parasites, such as treating asthma, and converting southerners into unproductive and lazy beings.
This podcast highlighted many unique qualities of parasites, such as the life of parasitic wasp. This parasite attacks cockroaches, and paralyzes them with a sting. Next, the wasp stings the cockroach again, and alters its brain, changing it into a zombie like state. The wasp then pulls the cockroach by its antennas into a burrow, where wasp eggs are laid, and the cockroach is sealed into the hole. The eggs hatch and feed on the cockroach, eventually killing it. Radiolab also explored how hookworms made Southerners lethargic. Scientists observed that Southerners were lazy and had pale skin, which may have been caused by a parasitic infection. They searched, and found hookworms in the soil, especially in latrines. It was learned most people went to the bathroom without shoes, and stepped on hookworms, that crawled into their feet. Hookworms can crawl no more than four feet before death, so it was decided to build outhouses that were more than six feet deep. The podcast also discussed the parasitic nematode and toxoplasma.
I was surprised at how interesting and astonishing this podcast was. While it was nauseating at times, I did learn, and was entertained. I thought it was crazy that Jasper Lawrence could even consider the idea of harvesting hookworms, and selling them to treat asthma or multiple sclerosis patients, especially without FDA testing to determine whether the procedure was safe. In addition, it was unbelievable that over eighty people would purchase hookworms knowing they were putting parasites in their body, and risking anemia. As well, I was shocked that the parasite toxoplasma could alter the way the brain works. Toxoplasmas’ ideal home is inside a cat, but it often lives in rats. So, toxoplasma makes cat urine appealing to rats, which results in the rats being consumed by cats. Ultimately, toxoplasma lives in a cat. Overall, I was intrigued and disgusted by this podcast.

Oct. 13 2009 10:01 PM
Sam A period 1

1) The podcast discusses many different types of parasites. The radio podcast interviews Carl Zimmer, a specialist in parasites mentions three examples of parasites(1. the parasitic wasp 2. the parasitic nematode and 3. the blood fluke ) The wasp goes after cockroaches, the nematode transfers its eggs from ants to birds, and the blood fluke enters through human feet and moves the veins. The show then goes on to talk about a study in the South. The question is originally asked why the Southerners look so sickly. It eventually led to the question where they went to the bathroom. It was concluded that anemia was linked to the soil. The farmers defecated barefoot in the soil, when they returned the hook worms they released had crawled up to four feet and had reentered in through their feet. The hook worms would slowly feed on their insides concluding the question why the Southerners looked so sickly. The next segment was about Jasper Lawrence, a farmer from England. Jasper moved to California and developed severe asthma and allergies. In 2004 he discovered a connection between parasites and allergies. People with hook worms had a 50% less chance of getting asthma. Jasper traveled to Africa and walked around latrines barefoot for 2 weeks, hoping to become infected with hook worms. When he returned home during allergy season, his allergies had disappeared. He then decided that he wanted to share his success and now sells hook worms for those in need. The last segment is about Ellen and her cat Moose. Moose had digestion problem and one day Ellen was scratched by Moose. Moose was tested and had a parasite called toxo plasma. Ellen worried that she may be infected with this parasite because she is pregnant. Toxo can only reproduce in cats. When a cat defecates, the toxo eggs are in the feces. Rats eat the feces, the toxo grows in the stomach of the rat and then travels to its brain mixing with its emotions. This makes cat urine appealing to the rat, the cat then eats the rat with the toxo in it. At the end of the radio podcast, a theory of a toxo plasma connection to schizophrenia is discussed.

2)-Parasites can be helpful or very bad
-There are tens of thousands of each type of parasite
- once outhouses were built, the hook worm in the south was no longer a problem because the feces were buried six feet deep so the worms could not travel the extra two feet.
- Parasites are very precise with what they are doing, for example the parasitic wasp sting the cockroach in a certain part of its brain which drugs it.
-The selling of hook worms is not FDA approved
- Hook worms co-exist with humans by telling the attack cells to stop attacking the body

3) The podcast was much more interesting then i expected it to be. I enjoyed how many real life examples were given. I found a lot of the information to be surprising such as all of the different types of parasites in the world. I never realized that having a parasite like a hook worm living inside you could be healthy for you. The only way I would want a parasite in me however, was if I was completely positive that it was only there to help.

Oct. 13 2009 09:21 PM

Why'd you write a full review????????????

Oct. 13 2009 08:40 PM
Jonathan C (1)

Jonathan Cabour

1. The WNYC pod-cast is an overview on different kinds of parasites, their positive and negative effects, and how they can effect/ "control" human life. The pod-cast begins with Carl, a science writer, who is an expert on parasites and written many books. They begin to discus if parasites are degenerates or not. Carl argues that they are not degenerates and gives three examples of different parasites to support this. The three examples he gives are a parasitic wasp which can brilliantly perform a "brain surgery" to control a roaches mind, a parasitic nematode which can cleverly get their way into their host to reproduce, and the blood fluke who can stay inside their host for years and years.
They then go on to explain a specific negative, involving the hookworm, effect that parasites have. The story begins in 1908 with a man who is thinking about how he can make more money by selling things to the southern market. Though, the south is in a down fall and the economy is terrible at the time. And he asks himself the question, why? So they then begin to describe how he sent a commission to see why the people aren't "rising to the occasion". Well it turns out that the people are "sick" in the way that they are pale and slow physically. After doing some more further research they discover that the people are sick because of a parasite called the hookworm. Southern people tend to use the same area for the bathroom. This allows the hookworm to get to them more easily by traveling from their facies through their bare feet to the inside of their bodies. It is then debatable that because of this discovery/getting the hookworm away and the invention of outhouses to keep hookworm away that the south was able to pick them selves up.
After that they then go on the talk about a positive effect of the hookworm. In this particular story a man named Jasper has a serious case of allergies and asthma. After dealing with it for too long he decides to find a way to get his allergies and asthma to subside. After reading about how hookworms can do this, he quickly tries to get one. After some difficulty and a trip to Africa he gets one and surprisingly enough it works and his allergies and asthma subdue. This is because normally your immune system is fighting all the foreign invaders in your body to keep you healthy. Though, some disease are caused by the immune system attacking the body it was designed to protect like allergies, asthma, and type one diabetes. The hookworm causes the immune to stop attacking by stimulating the cells which stops your allergies and asthma.
The final thing that is discussed in the pod-cast is that if parasites could possibly control people's behavior. There was a specific parasite called toxo that only can reproduce in cats. Though, it gets commonly stuck in rats. to get to back to the cat the parasite will go to the rats brain specifically that part of sexual arousal and make the rat love cat urine. This would allow the parasite to get back to the cat. It is hypothesized that these parasites could be effecting human behacior and cause them to like cats. Also toxo could cause schizophrenia in humans. This claim was supported by the fact that schizophrenia increased when cats began to be kept as a pet. Both these things would effect human behavior.

2. From this pod-cast i learned a decent amount of information about parasites and the roles they play. I was able to get an understanding of how parasites do what they do. It was interesting to see how the parasite travels/ gets to its host. One example of this is how the parasitic wasp takes over the roach's mind and lays its eggs on it. I also learned how the parasites have positive and negative effect on the world. examples of this is the sicknesses it caused down in the south and how the hookworm can cause your allergies and asthma to subside. The final thing i learned was an interesting hypothesis that was crated that a parasite, toxo, could be controlling human behavior.

3. I thought this was a very captivating pod-cast. I have not listened to many pod-cast in the past so I do not have much info to base my reaction off of it. Though, i thought it had very interesting information. They discussed thing that I have never heard about in a intriguing way that kept me listening. Also i liked the way they added sound effects to the pod-cast to make it more interesting. I also thought it was a little long.

Oct. 13 2009 08:08 PM
Eric B (1)

1. The podcast that I listened to is basically an argument between two parties about whether parasites are actually not as bad as they are made out to be or if in fact they are evil. One party talks about how like parasites, humans use what other organisms have made for ourselves and how smart and amazing parasites actually are also how some parasites can actually help people for example the man with the allergies, and the other party talks about how parasites cause bad things to happen people and other animals. Each side is argued through different examples of parasites and stories about them.

2. I learned many different details and stories about parasites in the podcast but some of the main things I learned are parasites can actually effect the brain and the behavior of humans and other organisms. Also I learned that some parasites can get into human bodies in creative ways for example the hook worm in the foot. Another thing i learned about the hook worm is that it can actually travel far distance to find a host. Also that it would be easy to avoid hookworms, for example that hookworms led to the invention of outhouses. I also never knew that people can actually purchase parasites.

3. At first i thought this podcast would be really boring because, one it is 1hr long and two its about parasites, but after listening to it i thought it was very interesting and given in a very fun and easy to listen to way. I also liked hearing the different arguments about whether parasites are bad or good and the point of view of each party.

Oct. 13 2009 05:06 PM
Tamara G (p.1)

1. I have listened to a podcast about parasites. The podcast opened with an explanation of a scene from the movie Alien. The scene had a guy who was having trouble breathing and chest pains, and then things burst out of the guy's chest and there were parasites in the man's body. The podcast then talks about parasites. Carl Zimmer is then introduced, and he tells us how he saw parasites on caterpillars growing up. The podcast then explains what parasites are capable of doing. Then, the podcast talks about hook worms which are a type of a parasite. We learn people with allergies are less likely to have them with hook worms in their body, and a person who had allergies tells his story how he got rid of his allergies from hook worms. Lastly, the podcast talks about toxoplasma which is another type of parasite. A pregnant woman tells her story about how toxoplasma got into her from a cat scratch.

2. What I have learned-
-Parasites are creatures living inside organisms/people
-Parasites attack caterpillars and grow on them
-Parasites gained ability to live inside species and give them infections
-Cockroaches vs. wasps (parasitic)-a wasp stings a cockroach and gets into the brain, then drugs the cockroach turning the cockroach into it’s slave
-Big black ants that look like its carrying a big red cherry are really parasites, the ant’s butt looks like a berry which attracts organisms the parasite wants to get into
-Hook worm's growth-day 1-1ft.2-2ft.3-3ft.4-4ft.5-4ft.6-4ft.7- dead hook worms
-People with allergies are 50% less likely to have allergies with hook worms inside them
-A hook worm is a tiny worm, but they have a big circular mouth with teeth which burrow through feet through blood and go to intendants
-Hook worms and people have a mutualistic relationship, the immune system gains advantage because once a hook worm gets in a gut it tells attack cells to stop attacking, hook worms gains place to live, you do something for worm, worm does something for you
-Hook worm and person-not always a mutualistic relationship, hook worms can cause amnia and diarrhea
-Toxoplasma is a parasite
-Toxoplasma can be in cat poop
-Toxoplasma can get into a person from a cat scratch because the cat can have it's poop on it's claws, but the parasite does not want to be in a human it wants to be inside a cat
-When toxoplasma gets inside a rodent it starts in a stomach of a rodent and makes it’s way up to the brain, it can then make a rodent like the smell of cats, so a rodent will approach a cat and usually wind up in a cat’s stomach where the parasite wants to be
-Some scientists believe toxoplasma can control you and guide emotions

3. My reaction to the podcast is I thought it was very interesting. I never knew anything about parasites besides small facts we learned in class until I listened to this podcast. I think parasites are interesting and the methods they use are extremely smart. One method I though they use which is smart is going into rodents and attracting the rodent to a cat, so the rodent ends up in a cat's stomach which is where the parasite wants to be. Even though I think parasites are interesting and smart I would never want one to be inside of me. It was rather smart of the person with severe allergies and asthma to travel to Africa, walk around with bare feet so he would get hook worms in him, but I would never do this. I personally think it is crazy for a person to put 50 hookworms inside of him. It seems like hook worms actually help humans, but some parasites kill other organisms like the wasp killing cockroaches. I don't think many people realize what parasites are capable of doing, even what parasites are. After listening to this podcast I think people should be more educated on parasites and their ability. I enjoyed listening to this podcast and learning a lot more then I knew before about parasites.

Oct. 13 2009 04:28 PM
Kendal P (1)

1.This podcast discussed whether parasites are good or bad. One man is arguing that the parasites are just like us, they use others to survive. The others are saying that the parasites are "evil" and they harm others. I listened to multiple different stories of different accounts of encounters with parasites.

2. I learned about the different types of parasites easily obtained long ago in the south and how they can be avoided. I also learned that some parasites can be considered good, even though I do not think so. Hook worms can help get rid of asthma and terrible allergies. Jasper uses hook worms to get rid of his allergies and extreme asthma. Jasper now sells hookworms. I never knew that you can buy parasites.

3. This podcast was very disturbing. If I never knew this information, my life would continue on. I see how this could be important to know, but the fact that Jasper walked around in other peoples waste is disturbing. I think that it is great that Jasper can live freely now, but I can never imagine putting any parasites in my body.

Oct. 13 2009 03:58 PM

WAY too cutty, as usual.

Oct. 13 2009 03:16 PM
Mark B (1)

1) The podcast discussed whether parasites are acceptable or as bad as everyone makes them out to be. there were two sides of the argument. One side of the argument discussed why parasites were such bad creatures and why people should despise them. The other side of the argument discussed the possible benefits of having a parasite within the body. After the debate several effects of parasites that are not commonly known were discussed like mental effects parasites have on organisms.

2)This podcast has changed the way that i see parasites. I've learned of the benefits of having some parasites such as the hookworm. Hookworms and other parasites like it have always seemed like a terrible thing to have, but from this podcast i learned of the possible benefits of having hookworms.Hookworms in the proper amount are actually beneficial to people with certain conditions such as severe allergies. Another fact i learned, which was not as positive, was the mental effects parasites can have. i have always thought parasites eat away at your body and tend to live in the middle and lower sections of the body. I had no idea that parasites could cause mental disorders such as schizophrenia.

3)I generally liked this podcast. It was informative without being completely bias. It gave great information about parasites which would be hard to find in many other places. Overall this podcast was interesting and informative.

Oct. 12 2009 08:42 PM
Kathryn Bettis

Dear Radiolab:

You are down one former fan, though I doubt it will matter to you, since I'm in the South.

I suppose I should have turned the hookworm piece off when it started with referencing the stereotype memorialized in the film Deliverance. Though you did graciously mention that "not all Southerners are slow", the piece was built on that premise.

The idea that Rockefeller's charity brigade of scientists paved the way to the South getting an economy is ridiculous. Evidently you, like Rockefeller's hookworm detectives, missed the farms.

And many other things.

The idea that Northern industrialists should be credited with the pit-toilet and the six-feet-under standard is equally offensive and bizarre. Are you skeptical, at all, of the history as written by the 'haves'? I thought you were, but I was mistaken.

So, northern open-minded radio producers, that's it for me. Although, I suppose I'm probably missing something since I'm the descendant of the pale, the slow, and the feces-footed.

Kathryn Bettis

Oct. 12 2009 05:51 PM
Nick M (1)

1) This podcast discussed the negative and positive effects of parasites, and gave interesting examples for both. However, it talked mostly about the negative effects. Examples such as wasps laying eggs on living caterpillars and "zombifying" cockroaches described the negative effects that parasites can have on organisms. One example of a man with severe allergies infecting himself with hookworms showed a positive effect, because the worms cured the allergies.

2) I learned that hookworms can apparently lessen or cure the effects of allergies, that they can crawl for just four feet, and that they are spread through feces. Also, I learned that outhouses were invented because of the hookworm problem in the south. Lastly, I also learned about Toxoplasma Gondii, which is a parasite that can only reproduce inside cats. If a rat becomes infected with it, the parasite "rewires" the rat's brain to be attracted to cats. Because of this, the rat will try to get close to a cat, and will most likely be eaten, spreading the parasite to the cat.

3) My reaction to this podcast is that it was very informative, and much less boring than I thought it would be. It was very disturbing and creepy though, to think that parasites might be in complete control of our thoughts and feelings.

Oct. 12 2009 05:41 PM
Jason B (1)

1. During this podcast, they were debating whether parasites were good or bad. They are moochers that feed off of other organisms, usually while they are still alive,like how the parasitic wasp lays it's eggs inside of a caterpillar and the wasp larva eventually eat its way out of the caterpillar. but parasites such as the hookworm were also showed to have positive effects as well. The hookworm helped control allergies.

2. i learned that parasites not only feed off of their host but can also, to some degree, control their host's mind, like making a rat attracted by the smell of cat urine. also that parasites can have positive effects on their host, such as controlling allergies, and that some parasites can move up to four feet outside of a host. A lot of it how ever was review of things i already knew about parasites

3. My reaction to this podcast was that it was interesting that parasites could control their host's mind to make them do something they never would.

Oct. 12 2009 12:40 PM
Adam M (1)

1) In this podcast, parasites were debated to be both good and bad. They cause good things to our health like take away allergies but they also cause bad things like anemia. A man who had terrible allergies heard about how a hookworm could help him get rid of his problems. So he walked around in Africa trying to get a hookworm in him so it would cure himself; this was an example of the good. One bad example was when they talked about the parasitic wasp which infected cockroaches with its larva and eventually the parasites ate away at the cockroaches insides until the new wasp popped out.

2) I learned that there was more to the hookworm and other parasites then just bad things like how they can cure allergies and various other things. I also learned the motive for creating the first outhouse. I learned about how some parasites enter the body like melting skin to get through the bottom of your foot or eating their way through and then traveling in your blood stream.

3) My reaction to this podcast was that I enjoyed learning more about these little creatures that could be inside of anybody.

Oct. 12 2009 09:56 AM
Molly R (1)

1) For the most part, this blog was about deciding if different parasites (such as the bloood luke and the hookworm) contribute completely negatively to our health, or if they have some positive effects on us as well. Specific examples were given such as: if it were not for the hookworm, outhouses would not have been thought of and created to improve hygeine.

2) I learned that the hookworm enters the human body by burrowing through the foot and into the circulatory system, eventually making its way up through our body. I learned that, in a way, parasites are similar to humans, for neither parasites nor humans are independent creatures, and that we both depend on other organisms for our survival.

3) my initial reaction to this podcast was that although it was not as uninteresting as i thought it was going to be,i did find it kind of repulsive how someone could produce AND sell to other people their own hookworms.

Oct. 10 2009 10:23 PM

I always believed there was a logical explanation as to why a rat would insist on coming into an apartment with five cats.

And you know, rats are not an easy kill.

Oct. 10 2009 03:59 PM
Soren Wheeler

Not that we know of. (I kind of doubt there is, but who knows?) If you find one, tell us.

Oct. 07 2009 09:50 PM

so if there is a parasite that makes you like cats is there also ones that make you like dogs too? Thanks Becky

Oct. 07 2009 06:31 PM

I saw this show about a girl named Jani with Schizophrenia on Oprah the other day, Oct 6th, and then I heard a Radiolab show (parasites). The last segment of the show was about the relationship between Toxoplasmosis and Schizophrenia and there was a very strange connection in both conversations about Cats and Rats. I couldn't help but wonder if there is any more of a connection to Jani's case. Check it out. Very strange.

Oct. 07 2009 05:52 PM
carolita johnson


Oct. 07 2009 05:39 PM

man! i'm listening to the parasitic wasp story... ugh.. .so NASTY... SO NASTY... you learn something new everyday,but MAN OH MAN!... ugh....

Oct. 07 2009 03:13 PM
Caroline H (2)

1. To summarise this lab report I would say it talks mostly about the benefits, negatives, and interesting key adaptations for the survival of the specific parasite. Some parasites can control the victims brain , some have special adaptations to lure other organisms in, and also some parasites that may be attributed to certain diseases such as Anaemia or Skitsofrenia .

2. I have learned that even though we perceive parasites to be bad and toxic and will make you sick, it can sometimes be the other way around without some parasites we could not digest food or survive at all. Also I have learned one theory on why the outhouse is a very deep hole, which is to keep the hook worm away from the point at which it dies and humans can not be affected by it. Also that there is such thing as a Hygiene hypothesis which states there is such thing as being over clean, which means you don't have specific bacteria to maintain your internal organs and digestive system. All in all, parasites can have good and bad affects on humans.
3. I thought this podcast was actually quite interesting, but also gruesome at some points. Its nice to know that some parasites can be beneficiary
but also quite deadly.

Oct. 06 2009 09:19 PM
Joe Pelayo

love the show, as usual. any news on viruses and bacteria? pros and cons? although this show was amazing, i was hopeing to learn a bit more about those two groups. Love the show!

Oct. 05 2009 04:47 PM

Alan, my baby is 3 months old now and, yes, she's totally fine...born absolutely healthy and beautiful.

(My cat, Moose, is also fine, by the way.)

My test showed that I was exposed to toxo in the past - most likely far before I was pregnant - and that I had developed antibodies to fight it that could cross the placenta and protect the baby in the case of a new infection.

The more speculative and subtle correlations which studies have suggested (car accidents, etc.) don't have me too worried. But, if in a few years my daughter starts trying to run other kids off the playground with her tricycle, I'll be sure to let everyone know.

Oct. 05 2009 08:45 AM

Just listened to this episode on WAMU. I am a fan . . . BUT . . . You've got to tell us if Helen Horne (sp?) had her baby and everything is OK?

Oct. 04 2009 07:05 PM

Hey Radiolab - Thanks for the recent podcast. I wanted to share a song here called 'Parasites'. In it, Daniel Kahn and the Painted Bird tell the stories of Toxiplasma Gondii, the Lancet liver fluke, and the Ampulex Compressa. Link:

Sep. 28 2009 02:32 PM
Peter Levy

Great showed. Two thoughts:

1) We humans are parasites too because we take sustenance from a lot of domesticated animals without killing them (milk from cows, eggs from chickens, etc.)

2) The first person to distill the helpful essence of hookworm would be rich beyond their wildest dreams.

Sep. 28 2009 01:43 PM
carlos von

"first time listener" - good facts - presentation techniques very annoying - too cute - you have conquered the challenges of presenting information via radio in as irritating a fashion as the current fad in TV science shows with quick cuts and cute visual tricks. The presentation methods have become more important than the scientific information - oh, well

Sep. 28 2009 01:18 AM

Question for Jad, Robert, Carl, relating to the question of the evil and Nature and intelligence (anyone else wondering this?), in that evil requires some degree of intent (even if that intent is banal): in the portion of the show about the parasitic wasp, Zimmer talks about keeping the cockroach alive in order to feed the young, but lots of animals feed on dead things in order to stay alive (and this is where the possibility of evil and intent might enter): why can't the wasp's eggs feed on a dead cockroach? Is it a matter of time; that is, a matter of how long the food needs to be available in order for the young to fully develop? (And, even if the cockroach could still serve the young if it were dead, is it evil if the cockroach isn't suffering?)

Sep. 27 2009 08:05 PM
I have been shit recently, but mostly because i th

[...] I haven’t heard this but the little write up makes me want to listen to it. [...]

Sep. 26 2009 05:31 AM

This was another great show. One suggestion, I often enjoy the musical interludes between segments, it would be great if you listed the music used in the show.

Sep. 21 2009 10:35 PM

Awesome show! I really loved this episode for so many reasons. First, I have MS and had read about the hook worm research being done right now. It was great to get a detailed scientific explanation along with an actual human example. In fact, that's precisely why I loved this episode -- the science was carried throughout, so that even the segments of personal stories still connected to (and helped illustrate) the science. Fantastic! Thank you!

Sep. 21 2009 05:00 PM
Andrey Revyakin

I have bad asthma which I, just like the hookworm guy, acquired after moving to the Bay Area. I can completely identify with his sense of desperation.

Interestingly, I have emailed him 3 days ago and never heard back. Perhaps he has been shut down. Publicity can sure backfire. I also emailed the research professor in UK and never heard back. He does say in the program that he gets an email every day from people asking to being infected.

I would not go to Cameroon though since it seems like a poorly controlled way of getting infected. Also, once you got N worms, I wonder at what N their population in your body stabilizes. I don't think they grow exponentially as another poster up there suggested.

Sep. 21 2009 02:23 PM

@ elsie (from earlier this morning): if you see this, i'd love to learn more about your situation. drop me an e-mail if you have a chance. thanks!

Sep. 21 2009 02:19 PM

unfortunately they will probably make hookworm trade/therapy illegal after this gets so much publicity. Most doctors are stupid: the fact that they haven't immediately jumped on this proves it.

Sep. 21 2009 01:10 PM

I suffered from Chronic Immune Disfunction Syndrome for 9 years and during that time, my allergies and asthma disappeared completely (cats, dogs, horses, pollen, dust, etc). In the last couple of years of my disease they also found a parasite in my gut (can't remember which but quite commonly found on unwashed salad). Once they cleared the parasite and my CIFDS subsided, my allergies started again. I mentioned this to all my doctors at the time but none had an answer for me about why this happened. I think your show has finally given me an answer! Amazing show.

Sep. 21 2009 04:47 AM

Very interesting episode. I wonder if the man who gave himself hookworms might find that the worms have done the job to his immune system and that he can now 'deworm' himself and live an allergy-free (and parasite-free) life.

Pig whipworms (Trichuris suis) are used to treat Crones disease. They do not stay in the human system, but are expelled by the body after a very short time. Still they seem to have a lasting positive impact on the immune system.

Sep. 20 2009 02:43 PM

why do you guys have so many sound effects in your show its very distracting

Sep. 18 2009 07:02 PM

I’ve been a fan since the start, but you’ve really outdone yourselves on this one.
The level of detail in the production quality, the fun you seem to have (as infectious as a cat’s scat on a rat) and the use of Debussy’s Cathédrale Engloutie at the end as the final kicker... I was off my bike seat, biking home on my nightly commute through the dark fern forests of Seattle, listening on good enough headphones to enjoy the beauty of the sound, and trying to figure out how you script this so that it’s all in the bag, but still seems spontaneous. Do you get everything lined up and then spring it on each other? Because it really seems like you’re genuinely surprised by each revelation.
Whatever sacrifices you must make to bring these creations to our ears, please know they are met by profound gratitude. You donate a deep sense of possibility to my iPod.

Sep. 18 2009 05:14 AM

Is Jasper Lawrence providing a legal service by mailing these organisms in the US? Is his company registered with the IRS? I would doubt it since his service is of dubious legality.

He's a pan-handler trying to strike gold by selling these common worms at a vastly inflated price. His company will probably be shut down within the year.

Sep. 16 2009 10:26 PM

hey guys.... decided to do a little research on hookworm & the south after listening to the show. I found a video from the rockefeller archives of a silent movie produced by Rockefeller in 1920 to educate southerners about the dangers of hookworm.

Sep. 16 2009 07:09 PM

I have Crohn's disease and hemochromatosis, so the hookworm's benefits - and also side effects of overdosing - are really a win-win for me! :)

Sep. 16 2009 06:34 PM

What's the song on the podcast at the break just before the cat segment? Is that the hookworm song everyone has been talking about?

Sep. 16 2009 05:38 PM

Great! Another RadioLab show that has completely messed with my life! Curse you, RadioLab;)

Of course,they could have told us if the toxoplasmosis condition was curable, couldn't they?

Sep. 16 2009 10:42 AM
Joe Adams

Check out the amazing deer botfly that can affect humans. As an adult, it's a fast moving fly. It bites its host and deposits eggs that hatch in the guts of the host. In the larval state it lives like a parasitic worm in the guts and eventually is deposited.

Sep. 16 2009 08:31 AM

I love Radio Lab! I am anxious for the next episode. Your shows make me go and research new things in science, history, etc. Thank you.

Sep. 15 2009 11:29 PM

I have officially fallen back in love with Radio Lab. Please keep it up... consistently. I know the economic situation has been tough, and season 1 was tough to top, but this show has wowed and wooed me yet again. And congratulation to Mr. Jad Abumrad on his new baby!!

Sep. 15 2009 09:41 PM

What a great show, I shared it with my workmates, we work for a company who are developing immune response therapies, I expect this competition may blow our minds.

Sep. 15 2009 07:46 PM

@Peter Clarke:

You have *one* definition of theory right, but you seem to have entirely missed the two other accepted and common definitions which *do* allow for the usages of which you gripe to be proper and correct:

Sep. 15 2009 07:34 PM

I've just tuned in on your show, and I LOVE it :-)

Sep. 15 2009 03:31 PM

Very nice use of Phish's "Ester" during the cockroach/puppet segment. That is by far one of the creepier puppet songs.

Also, my cat really went crazy during what I call the "cat jam" of meows during the toxo segment. Is she trying to tell me something about mind control?

Sep. 15 2009 09:08 AM
Peter Clarke

Love your show and listen regularly. Something I wish you would explore further is the misuse of "theory." One of your interviewers said something was " just a theory," however, as I recall, a theory is something that can be recreated through experiments. A small note, however, I hear the Theory of Evolution dismissed as "just a theory" by so many in the Creationist camp. The misuse leads to misunderstanding.

Sep. 14 2009 08:22 PM

@ Kyle

Sep. 14 2009 02:36 PM

Mary - thanks for saying what I was going to! I am also a veterinarian, and have worked w/ toxoplasma, so I, too, always flinch at the bad rap toxo gets. Thanks for clearing things up.

Sep. 13 2009 05:11 PM
Kyle D.C.

how did you guys miss this one?

Sep. 12 2009 12:19 PM

Marc: Most people who contract toxoplasmosis never even know they've had it. The symptoms are usually more like a bad cold. Additionally, toxoplasma gondii is a protozoa. Although attempts have been made to "vaccinate" against protozoan species (such as giardia), no one has discovered a way to make an effective preventive against this class of organism. If you can figure this out, you'll be wealthy. Get to work! :)

Sep. 11 2009 11:57 PM

@ Jasper

Why aren't people beating down your door? Possibly the $2900-6400 price tag for a treatment that by your own admission is harvested from your own shite.

That and being unwilling to jump the gun on research, evidence and the FDA. I think the hygiene hypothesis is interesting but capitalizing on this treatment before it is borne out by the evidence smacks the opportunism.

Sep. 11 2009 04:16 PM
Marc Naimark

Great show!

Re toxoplasmosis: This sounds sufficiently dangerous when it does occur that I wonder why there is no vaccination for it. Anyone have an answer?

Re hookworms: I was not convinced by the coevolution explanation. The explanation given was that is was a symbiotic relationship in which the parasite gets food and shelter, and the host gets a well-regulated immune system. It seems to me much more sensible to explain that hookworms and other parasites have developed ways to reduce the host's immune response in order to protect themselves from destruction. The result is the same, but the rationale seems more plausible.

re: Jasper's allergies. I used to suffer from hayfever about as severe as Jasper's. Antihistimines and other medical treatments were nearly useless to deal with the symptoms. After several failed attempts (for an interesting reason I won't go into here), I finally had a very successful desensitization. Jasper spoke of treatment for asthma, but I didn't hear anything about an attempt to treat his allergies by desensitization. Any info on that? I know I would rather go through three years of biweekly shots rather than march in human feces in the Cameroon.

Sep. 11 2009 04:03 PM

I loved this episode, as I do all of your shows. However, as a veterinarian, I am always a bit sqeamish about the misinformation which gets passed around regarding pregnancy and toxoplasmosis infection. Your show, thankfully, did not include any of the major myths about toxoplasmosis. Sadly though, even with a much more educated public, I still hear clients tell me that a doctor or nurse has advised them to get rid of their cat during pregnancy. Certainly, there can be terrible consequences of infection for a pregnant woman, however, if you have already been infected with toxo (about 1/3 of US residents) a second infection should not effect a fetus. It is certainly prudent for pregnant women to refrain from cleaning the litterbox, but overall the risk of catching toxoplasmosis from your cat is rather small.
1.Toxoplasma gondii affects most animals (most notably sheep, cats, and humans), but even insects, fish, and earthworms may be carriers.

2.Most human infections result from eating tissue stages of Toxoplasma in undercooked meat. Infection is through the gastrointestinal tract. It is highly unlikely that a cat scratch (even if the claw is coated in cat feces) would transmit toxoplasmosis, unless you put that scratched body part in your mouth.

3.Usually a cat will only shed oocysts after the first infection of Toxoplasma, which usually occurs very early in life. Cats shedding oocysts generally do so for 5 to 14 days. Oocysts must be exposed to the air for 24 to 48 hours to sporulate and become infective.

4.Although it is possible to get toxoplasmosis from cats, no correlation has been found between cat ownership and toxoplasma infection. There is, however, a very strong association between Toxoplasma infection and working with raw meat as in a slaughterhouse or as a butcher. Be careful handling raw meat. Probably the most important thing is to be careful when cooking raw meat, especially lamb and pork.

Sensible precautions are always in order, but cats and dogs are both capable of carrying parasites which are far more common and far more problematic for humans than toxoplasmosis.

Sep. 11 2009 01:06 AM
Rafael Puyana

Guys.. awesome as always.. your podcast are the favorite parasites of my ipod ! Hope some they you get funded with budget to translate all that great stuff to spanish so millions can learn and have fun.

Sep. 10 2009 07:38 PM

Jasper, you mentioned type I diabetes in your setup and I got really excited but it didn't come up again. Has hookworm ever been used to alleviate type I diabetes?

Sep. 10 2009 05:08 PM

Carolyn (and others who liked the hookworm song),

It's actually just the J.J. Cale song "Call me the Breeze" (plus an impromptu hookworm chant). So no mp3, sorry.


Sep. 10 2009 02:46 PM

I loved the hookworm song too--is there an mp3 of it around?

Sep. 10 2009 01:33 PM

How about a follow up on how pregnancy might be like a parasitic infection? The embryo burrows into your uterine lining and feeds off you for 40 weeks (18 years?) and will leach calcium from your bones if you don't take in enough. Just saying...

Sep. 10 2009 12:56 PM

For everyone who wants to hear about bot flies on RadioLab, you're just a year late:

Sep. 10 2009 08:39 AM

Botfly Maggot Removal Video:

Sep. 09 2009 09:06 PM

@Adam: The hookworm enters a host as a larva and then matures in the gut. Once there it releases millions of eggs but those don't hatch unless they're in some nice soil. So interestingly unless you keep reinfecting yourself a hookworm infection will be static and then die off.

Sep. 09 2009 04:59 PM

This might actually be the scariest episode of RadioLab to date! Imagine: numerous parasites and microorganisms help us make decisions or manipulate the way we feel. Ignorance is bliss?

Sep. 09 2009 03:14 PM

Anything with an Alien reference... for the win.

Sep. 09 2009 02:44 PM

Excellent show once again!

Sep. 09 2009 12:12 PM
Jasper Lawrence

Nicely done, and I had serious reservations about this interview when I did it.

As an aside my ex, the one who loved cats over me, falls into the latter category of the program. For years I had thought TG might be responsible for her behavior, so an awesome program, from my point of view.

Perfect, altogether.


Sep. 08 2009 10:55 PM

Zombie cockroaches... great name for an early 80's punk band. Fabulous show as usual, but ugh, I don't think I'll ever sleep again.

Sep. 08 2009 08:01 PM

Found myself itching and squirming but listened to the end. I love this show!

Sep. 08 2009 04:09 PM

I don't get how a dose of 10 vs. 50 hook worms mattered to the researcher when they grow exponentially such that you excrete millions. It should just peed things up very slightly, but why would you have a stable population that is larger.

Sep. 08 2009 02:59 PM
Connor Walsh

I have that Hookworm song stuck in my head. Like a parasite?

Sep. 08 2009 02:35 PM

Carl Zimmer! My hero! :) Great show!

Sep. 08 2009 01:41 PM

great show -- as usual.

that said, carl zimmer's being more than a little disingenuous in his paraphrasing darwin as opining that god shouldn't "be blamed" for the existence of parasitic wasps.

darwin's actual quote on the subject is closer to the spirit of jad's observation of the process as 'evil'. to wit: "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars."

darwin's move toward agnosticism/atheism later in his life is well-documented. the quote above is an example of how he tried to ride the fence when expressing his growing doubts while respecting his wife's religious devoutness.

small point, maybe -- and i'd rather not start a atheist/believer mud-slinging match. but the theme of the show is one of the most solid (& very entertaining!) contemporary arguments in favor of natural selection out there.



Sep. 08 2009 11:38 AM
Ken C

This episode gave me the willies. I love it!!!

Sep. 08 2009 11:27 AM

great show. New season is off to a great start.

Sep. 08 2009 08:44 AM
Evan Pankey

I really like the hookworm asthma/allergy hypothesis. I hope someone is funding research in that area.

Sep. 08 2009 08:40 AM

Great show as per usual.

Fun to listen to but the idea of these things being anywhere and possibly everywhere is creepy and exciting at the same time.

Feeling tingly already.

Sep. 08 2009 06:19 AM

No Bot flies?

An entire show on parasites, and no fleeting mention of the larva that lay in that Harvard guy's head? There are videos on the web of bot fly larva extractions, many of them (at least two) they are becoming the new internet porn. They are! The people making these videos are signing on to Stephen Johnson's website and fooling google to make them more popular. They are!

And you had the story first but you forgot didn't you? Having a bot fly in your hair has to be as cool as selling your hookworms (I love that image though) to people with allergies.

Sep. 07 2009 10:47 PM

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