Angelika writes:


Thank you for a fun and always interesting program!

My guess is that the case described in episode 235 had a primary toxoplasma infection. The venison was not well cooked and, if my guess is correct, had not been frozen preciously(since that kills off the latent toxo cysts in the muscle cells).

Often a mild infection with swollen lymph nodes is a well known characteristic. The test must have been a serology test showing presence of anti-toxo IgM antibodies in the patiens serum. No treatment unless the patient is immunosuppressed.

Often no sequele although I have seen a few patients who were left with permanent visual reduction due to primary ocular toxoplasmosis infection in my job as an Ophthalmologist since the early 1990’s.

Greetings from Lund, Sweden


Rod writes:

Hi all at TWIP. I studied some parasitology back in the 1980s as part of a degree in biological sciences at North East London Polytechnic. I have been enjoying listening to TWIP for the last few years. This is the first time I have tried to put my parasitological knowledge into practice. From the symptoms- aching muscles- and consumption of undercooked venison/ pork my best guess is that they have trichinellosis.

Thanks for all you do keeping us informed, educated and entertained.

Rod Jacob – North Portugal.

John writes:

Hello esteemed hosts, I am happy to report that I have completed listening to this podcast from the first episode and I appreciate you all and the interesting science I’m exposed to as much as a layman can be.  I figure jumping headfirst with a guess is in order to celebrate being current and able to submit a guess.  If nothing else, being spectacularly wrong can encourage other bashful listeners to participate regardless of knowledge level because something is always learned in the process making it worthwhile.

The things I noted are that we have an immunocompetent patient, testing resulted in not needing to be treated but did get something, the many people at this feast were potentially asymptomatic, the venison is a common thread between them and not necessarily the boar, and no diarrhea.

I focused on parasites that can occur in undercooked venison, mostly because I am not nearly good enough at this to start with a differential that doesn’t have the big clue we are examining this from the lens of parasitism, and I came up with Toxoplasma gondii and Trichinella spiralis.  And while reading the freely available pdf of PD7 I got so excited that T. Gondii seemed to fit that I began to worry that I was motivated in my reasoning because it was my first guess.  But, many experience this asymptomatically explaining most guests being fine, and treatment isn’t necessary for immunocompetent so I shelved this to see if I could eliminate the other hit as Dickson suggested to do.

Trichinella while found in boars did not seem to suggest undercooked venison would necessarily be a vector but I also didn’t know well enough if cross contamination of preparation could still cause this.  However, some symptoms like fatigue can match, diarrhea and vomiting didn’t.  Since Dr. Griffin highlighted diarrhea, and the fact that pigs are the main reservoir, I focused back on T Gondii.

T Gondii exposure can occur form oral ingestion of undercooked meat, venison included which all affected reported consuming.  Clinical disease can consist of acute mono-like illness, fever, cervical adenopathy, fatigue but not diarrhea.  And, 80-90% of acquired infections are asymptomatic which matches what happened to the crowd that attended the meal.  A PCR test can confirm among other methods and mild infection in immunocompetent patients does not require therapy but drugs of choice are pyrimethamine and sulfadiazine.

So my guess is Toxoplasma gondii, and if I’m wrong I know I will learn something anyway.  After listening to all your episodes I use my meat thermometer religiously now and I feel more mindful of the safety we enjoy in this country due to regulatory agencies and all the free knowledge provided by experts sharing their knowledge, like here at microbetv.  Thank you all for your noble philanthropy, this educational organization and outreach you do is truly a gift to humanity of the first order and I can’t sing your praises to others enough for these programs.


Joann writes:

Dear TWIP Professors,

I’m sitting in an airport waiting for my plane to arrive and fly me to Philadelphia to see my grandchildren. To pass the time I thought I’d do the case study of the group of friends who felt lousy with myalgia one week after eating a large meal of venison and wild boar.

My guess is that this is a case of trichinosis. I checked my guess by doing a quick google search verifying that one can get trichinosis from eating undercooked venison. The CDC website says that once the parasite encysts in the muscle there is no treatment. That is unfortunate. I wonder if the positive test that Dr. Griffin referred to is a biopsy of the affected muscle with microscopic visualization of the parasite’s cysts.

I look forward to hearing the responses from the other twipsters. Thank you for helping me to pass the time in this boring airport.

Best regards,


Megan writes:

Greetings and salutations from an unusually sunny Pacific Northwest!

My guess for this episode 235 is Trichinella spiralis (or a closely related Trichinella species). Trichinella spiralis is found in game meat and after a week’s incubation can cause the observed symptoms of muscle pain, fever, fatigue, and swelling. Likely by the time the patient was tested all the larvae were embedded in muscle tissue at which point they can’t be killed and anti-inflammatory drugs and painkillers could be used to keep the patient more comfortable. The positive test was likely for IgG antibodies. I suspect the parasite load of the meat was small since some people seemed to be asymptomatic and the patient in this case did not experience GI symptoms beforehand as is usually seen in more severe cases.

Thanks for creating such an engaging podcast,


David writes:

Dear TWiP Team,

Thank you as always for another interesting episode, and a stimulating clinical case. 

Given the description of the symptoms – including no digestive issues, the helpful hint regarding undercooked venison, and the lack of a need for treatment, led me towards searches for risks of undercooked meat causing problems that require no treatment (in general).

Based on results from looking through the CDC, Mayo Clinic,, and of course my trusted 7th edition of Parasitic Diseases pdf version, my guess for this case is an infection from Toxoplasma gondii, resulting in toxoplasmosis. 

Looking forward to hearing the answer in an upcoming episode.

Thanks again for all you do.

David in Maryland

Tuomas writes:

Hello everyone,

I wish to express my true gratitude for all the podcasts on Microbe dot tv.

Here is the report I am filing for the case from TWiP 235:

I am currently burning the TWiP candle at both ends by listening to episodes both from oldest to newest and newest to oldest. Starting from episode 12, Vincent and Dickson have hammered home that Toxoplasma gondii is the most successful parasite in the world. At least of mammals.

Consequently I was ready to diagnose immediately after the first sentence: “I hope this case is as successful as the parasite is.” I realize I am demonstrating the second worst kind of confirmation bias, and that my differential is entirely post hoc. I tried to identify any signs, symptoms or hints that would force me to seriously consider ruling out acute toxoplasmosis. The timing is my biggest obstacle, but my interpretation of Figure 11.7. allows me to keep believing I will be successful if I just stick to the first thought that popped into my head. As successful as Daniel says toxo is, in episode 171.

If hearing about toxoplasmosis makes me think I have it, there’s a good chance I do have it. I often experience the typical clinical syndrome of chronic toxoplasmosis in immunocompetent adults: an asymptotic state. I’ve been exposed to and have eaten, cat feces and uncooked meat, respectively.

When Daniel says he hopes this will be a fun case, my ears perk up to note any vague language which might seek to mask the potential animal nature of the patient, or conversely to identify any details that indicate Daniel is referring to a human. Based on the available evidence, I have concluded the patient is indeed human. Differential includes penguin and dog.

The description of the circumstances and the progression of the disease is strongly reminiscent of the case of the four Cornell medical students of the toxoplasmocalypse which Dickson recounted in episode 13. The patient has ingested a large inoculum of T. gondii oocysts from undercooked meat. In an immunocompetent adult this causes acute toxoplasmosis, which is self-limiting once acquired immunity forces tachyzoites to enpseudocyst or pseudoencyst themselves. Myalgia could be tachyzoites invading muscle cells. The swollen lymph nodes in the neck are caused by tachyzoites traveling there aboard macrophages. The lack of GI symptoms rules out many other potential infections and is consistent with toxoplasmosis.

Trichinella is very successful, but not as successful as toxo. Fatigue from venison could be chronic wasting disease. Fortunately no human cases of CWD are known. Symptoms also fit infectious Hodgkin lymphoma, which doesn’t exist. Another possibility is a zoonotic spillover of Epstein-Barr virus from undercooked cervid flesh. These latter three have a combined success of zero.

Ideally, deer would flash freeze cat feces with liquid nitrogen before accidentally ingesting any. However, as Vincent has previously pointed out, deer are quite frugal. It has further proven difficult to motivate deer to invest in technology that doesn’t benefit them and which they do not understand.

best regards,


P.S. I reached out to the owner of the venue where the meal was served and they told me the venison was fine. It was in fact cooked so well that the inside of the meat was still glowing red hot when it was served. He went on to make the frivolous claim that while the people who became ill reported no toxic habits, he had personally seen one of them smoking cat feces in the parking lot.

Håkon writes:

Greetings from balmy Athens,

This month’s case was an interesting one to ponder. Based on the mirth in Dickson’s voice when discussing the new case, as well as the background of diffuse myalgia and wild game being served undercooked- I’d have to go with a case of trichinellosis. While it was somewhat suspicious not everyone who ate the wild boar had symptoms- it made me wonder if perhaps their individual cuts of meat had less larvae in them or were perhaps more thoroughly cooked. Without having tried it myself I suppose I’ll never know. While Sarcocystis nesbitti and cysticercosis occurred to me as differentials based on clinical signs alone, the clinical case history fits better with a trichinella infection. I don’t know if you all all saw this article, but it was a neat study looking at what anthelmintics might work to inactivate larvae encysted in pigs prior to their slaughter and entrance into the food supply chain.

Thanks again!


Eyal writes:

Dear Vincent and the sages of the eukaryotic world.

Greetings from Sydney and the land down under.

Winter is slowly approaching and the temperatures are dropping. 7-8 degrees centigrade at night is not cold for NY weather but for us here in Sydney it’s considered nippy. 

I’ll keep my human guess short this week as I also tested Open AIs latest model, ChatGPT-4o, which was released last week. 

Human guess:

Looking through google for parasites infecting both Deer as well as Humans 4 came up: Toxoplasma gondii, Trichinella spp, Cryptosporidium spp, and Giardia spp.

I’ve ruled out Crypto and Giardia as those would result in gastrointestinal symptoms which are missing in the case.

Between Trichinella and Toxo I would lean towards Trichinella as Toxo typically doesn’t result in severe systemic symptoms and apparently Trichinella is famous for causing severe myalgia. Also I picked up on Vincent’s comments to Dickson, leading me to believe this specific parasite is of special interest to Dickson?

Human and Artificial collaboration:

Not sure if you and the listeners are aware. But, over the last year there has been a ‘space race’ going on between major industry incumbents and newcomers to develop competent AI assistants. Last week 2 major announcements by OpenAI and Google were made. Both are a huge leap forwards in terms of logic, accuracy and context the AI can analyseat the same time.

Personally I think that these types of tools can be a huge boon for learning and understanding.

As always thank you all so much for all you do.



Carol writes:

Hello all– As soon as I heard this case, especially with the consumption of wild boar, a pig by another name, and venison, I immediately knew it had to be Trichinella species parasites. The most common species is T. spiralis and I suspect that is the one causing all the difficulty. I know that two other species exist, T. pseudospiralis  and T. britovi, but must admit that I do not know much about either without doing some research. Maybe Dr. Despommier who is the expert in this parasite, can shed some light on the differences from T. spiralis? Anyway, the dinner friends must have received a pretty large dose of the parasite, since lower than 10 larvae per gram of tissue consumed do not usually produce symptoms. Yikes for them! Being that I am a lab tech, I’d love to know if an eosinophil count was done on their blood samples. I would expect it to be elevated. Maybe in a few weeks (3 weeks or later), serologic testing for Trichinella spiralis antibody could be done for confirmation of the diagnosis. The dinner chefs should have done a quick freeze at -40 degrees C to kill the parasites but maybe it was fresh from a day’s hunt. Treatment should be given to stop any adult worms still in the intestine from producing larvae, using steroids and either albendazole or mebendazole, since the friends are experiencing severe symptoms. Unfortunately, those larvae which have already migrated into the muscle tissues are there for life, as no meds are known to kill tissue larvae, as far as I know. I love lifelong friends but don’t think I would want this particular one. Hope to win a book someday as I really enjoy your podcasts.



James writes:

Actually there are several parasites one might gather from meat. Trichinella is the leading contender in my mind. I’m thinking of the Boar here although I guess the Deer could also be the source. Disease course seems about right.

Toxoplasmosis we usually think of Cat Litter/feces, but you can also get it from raw meat. Seems like this may be the most global of parasites with very little host specificity. Have you heard of the hypothesis that Toxo causes risk-taking behavior in the host? Mice lose their fear of cat urine and people drive too fast? Is the Toxo helping to feed the felines? But primary Toxo can give you a flu-like or Mono-like acute illness.

Some cysticerci from tapeworms are I guess in the differential.

But I’m thinking Dixon disease, or Trichinella spiralis.

James M. Small, MD PhD FCAP

Professor of Microbiology and Pathology

Director of Clinical Career Advising

Jason writes:

Greetings TWiP hosts!

It is a pleasant 18 degrees C here in Seattle and the city’s flowers are in full bloom.

In the Case of the Distressed Deer Diner from episode 235, the patient would seem to have become infected with Toxoplasma gondii as a result of eating undercooked venison. 

An IgM assay test can provide laboratory confirmation of acute-stage toxoplasmosis.

As this patient is immunocompetent, it is likely that the disease progression will be both mild and self-limited. Therapy (via pyrimethamine and sulfadiazine) is not indicated unless more serious signs and symptoms manifest. 

Worm regards,


Kenzie writes:

I believe that the causative agent of this case study is Toxoplasma gondii. Symptoms of Toxoplasmosis include fatigue, swollen lymph nodes (specifically in the neck), fever, myalgia, and headache. This parasite is often transmitted through undercooked meat, such as venison and boar. This pathogen is a single cell, comma shaped parasite that is found worldwide. Typically, no treatment is necessary, though supportive measures may be taken. The incubation period of this infection is 4 to 21 days. The symptoms, incubation period, and treatment match the symptoms presented in the case study almost perfectly. When considering this parasite, it is important to know that most people who are infected appear asymptomatic, which explains why most attendees of the dinner did not get sick afterward. 

One interesting fact about this parasite is that it can be associated with several cases of schizophrenia. 

Justin writes:

Hello wonderful hosts, 

My first thought for a parasitic infection from undercooked venison was trichinella, though the symptoms do not match, and the treatment suggestion would have been different in that case.

After some research, Toxoplasma gondii came up as a potential, as infections can occur with improper handling of venison meat. The symptoms fit very well, as does the treatment. Considering that the seropositivity for toxo in America is estimated to be 11%, I wonder how many of the people unaffected had immunity due to past exposure.

Thanks for the great podcast, 


Nathan writes:

Hi Team, and thank you for continuing to release a fascinating podcast with interesting cases!

I learned about the podcast as I’m one of Christina Naula’s Diploma in Tropical Medicine and Hygiene students at Glasgow University, and wanted to submit my suggestion for the most recent cases (hopefully not too late). I listened to this episode on a long drive as some revision in the lead up to the upcoming DTMH exam.

A case of illness in some but not all attendants at an event serving bravely undercooked venison and boar, with presentation of myalgia, fever, sore throat and lymphadenopathy a week after the event could fit with infection of Toxoplasma gondii. This protozoan parasite can be sourced from raw or undercooked venison, and although most immunocompetent hosts are asymptomatic from infection around 10-20% can present with cervical lymphadenopathy and/or a flu-like illness, with an incubation period of around 5-23 days (in keeping with the timing of this case). In most cases no treatment is required, which would also fit with the reassurance given alongside his positive test result.

Hope I’m right in my first submission!

Nathan Williamson

(a General Practitioner in Newcastle-upon-Tyne, England)

Martha writes:

Dear TWiP hosts,

I enjoy these TWiP cases although I tend to get sucked down one or more rabbit holes. So I will try to be prompt and brief.

The CDC recommends cooking venison to an internal temperature of 160F. The meat thermometer was patented in 1942, so one does not need to poke one’s thenar eminence to gauge doneness. 

But there are a number of sites on the internet suggesting internal temperature as low as 120- 130F for venison. So it is not surprising that these people were eating rare meat. (Since I googled for this information, venison recipes have been showing up in my google news stream.) 

The prevalence of infected deer in the USA varies by region, ranging from 15-74%. In the USA 12-18% of the human population have been infected. 

So it is not surprising that the event featuring undercooked wild game resulted in some symptomatic infections. Those without symptoms may have had a prior infection or be in that portion of the population that is asymptomatic with infection. 

Since the patient is symptomatic it is not unreasonable to treat him even though he is immunocompetent.  

Ideally those who put on this event would notify all attendees. For those people who are immune compromised or pregnant an infection with Toxoplasma gondii is more worrisome.

Best wishes to you all


Anne writes:

Hi all,

Regarding the boar and venison dinner participants, my initial guess was Trichinella spiralis, because of the boar meat and  Dickson’s confidence.  However, reading more about parasitic diseases associated with consumption of undercooked meats and the clinical presentation including cervical lymphadenomegaly and  fever, my guess is Toxoplasma gondii.

As always thank you for all you do for science education.

Kind regards,


Rafid writes:

Hello TWIP team,

I think there are two possible parasitic diagnoses for a group of people getting sick after eating undercooked boar and venison. It could be trichenella spiralis for the boar or toxoplasmosis gondii from the venison. Although primo toxo infection is usually asymptomatic or mild , flu like symptoms with generalized adenopathy occasionally occurs. For those interested, in the May 1 2024 issue of the New England Journal of Medicine there is a clinical problem case of a healthy 30 year old woman who developed acute respiratory failure from severe bilateral pneumonia requiring ICU and intubation. It was only after 3 days of intubation that a history wad  elicited that she cooked and ate venison 20 days before getting ill ( the deer was hunted in Alabama ).  The patient had a very high parasitemia and responded to Trimethoprim-sulfamethoxazole. There was a concern that virulent Amazonian T. Gondii had reached the USA but pcr showed it was regular T. Gondii. The patient was checked for various immunodeficiencies and was found to be normal.

Back to our case. Toxoplasmosis is my humble guess


First Vienna Parasitology Passion Club writes:

“Deer” TWIP Hosts, 

This case about a group of multiple sick dinner guests after eating undercooked venison and wild boar leaves us with  only a small number of differential diagnoses. While white tail deer are hosts to a veritable cornucopia of parasitic infections, only few are pathogenic to humans: toxoplasmosis and trichinosis.

While trichinosis can be contracted by eating undercooked boar meat, which was served at the dinner party, we would expect the majority of the guests to develop GI symptoms shortly afterwards and more systemic symptoms a while later. Furthermore, several characteristic symptoms of trichinosis, like periorbital edema, rash and conjunctivitis, are conspicuously absent here. Finally, trichinosis is a potentially fatal disease that should be treated, if possible, with albendazole or mebendazole, while the case talks of self limiting disease.

Toxoplasmosis is often asymptomatic, although up to 20% of immunocompetent adults develop symptoms during acute infection. Symptoms often include unspecific flu-like symptoms, lymphadenopathy, fatigue and myalgia – as also seen in our patients. We do think this may be the more likely diagnosis, considering deer rarely snack on small rodents. 

Thank you for putting (venis-)on such a great “game”. All the best, 

Michelle and Alexander from the First Vienna Parasitology Passion Club

-Paul writes:

Hi all,

Toxoplasmosis from undercooked venison


(I have won a book already, thanks).

Ed writes:

Dear TWiP gang:

Greetings from Southeast Minnesota where it has rained about every other day recently and everything is green and blooming. Today is a little cooler, high 64 F 18C.

Severe myalgias and facial swelling 1 week after ingestion of game meat, along with Dickson’s interest, made me jump straight to trichinellosis. I am puzzled why the patient was initially told no treatment was needed. Coincidentally, an outbreak of trichinellosis from T. nativa acquired from undercooked Canadian black bear meat was described just this week in MMWR from the CDC.

I am a physician and have an old microscope and a collection of vintage slides. I attach a photomicrograph of a beautiful circa 1950 slide of Trichinella spiralis in a rat tongue. The image was obtained with a 4X objective and spans about 3 mm across. Maybe some of the TWiP gang need a new screensaver? 

long time listener and first time guesser,

Ed in Minnesota