Case guesses:

DrSciGirl writes:

Based on the high muscle enzyme results (LDH, CK), I’d guess trichinosis.



Jerry writes:

Man from Alaska

Trichinella from bear

Anasakis from salmon

Eugene writes:

I would say that the patient is suffering from Giardia. The diarrhea and stomach symptoms are the only classic Giardia symptoms, but my own experience many years ago with Giardia taught me that there are very large number of possible symptoms which can show up that do not in anyway indicate Giardia as the cause. Drinking water, untreated, from a stream is a pretty good way of getting Giardia almost anywhere in the wilderness.

In my own case, I had nearly a week of acid reflux, something I had never experienced in my entire life prior to that time. I found myself progressively weaker with a very uncharacteristic lethargy. After the diarrhea showed up I headed to the clinic to get it treated. The blood tests that were given to me indicated liver and pancreatic problems severe enough that my doctor required that I have a weekly blood test for the next month to insure that everything was stabilized. As a Mountain Rescue paramedic, I was very aware of Giardia and its usual list of symptoms. My own did not tick off any recognition.

Iosif writes:

Dear Twipanosomes,

For this case, my main guess would be the nematode Trichinella nativa. This is a parasite that can be found in uncooked (or in this case undercooked) muscle. Once it is in the GI system it could be activated by the digestion of the muscle it is embedded in. The larvae then embed themselves in the GI wall and mature into adult worms. From there they spawn new larvae that use the bloodstream and the lymphatic system to find new muscle to embed themselves into. From there they wait until new opportunities arise, specifically being eaten by another animal. The infection is usually asymptomatic unless there is a significant parasitic load, in which case there would be muscle weakness, muscle pain, diarrhea, abdominal pain, etc. The main giveaway from this case (if I am right) is the periorbital edema and the location. I don’t know of many parasites that could cause the edema and the fact that the meat was frozen leads me to suspect that the parasite is resistant to freezing (such as nativa). I would think that you could do an ELISA to confirm the diagnosis, but I would probably get a muscle biopsy since it would offer more certainty and you could use it to check for other pathologies (that I will discuss below.) Albendazole would be my drug of choice as treatment.

Other parasites:

Cystercicosis: Taenia Solium could form cysts in muscles, but there was no mention of pigs in this case! Also, there is usually a much more mild response in the muscles and more serious effects from the cysticerci in the brain.

Toxoplasmosis: I know that toxoplasma could cause myositis in the acute phase of the infection as well as the fever and other things, but it shouldn’t cause eosinophilia:

Microsporidia: A protozoan that is found in fish and could be transferred to humans …that are immunocompromised. The symptoms actually match fairly well otherwise and he does eat fish.

Echinococcus: It can form cysts in muscles which would be problematic; however, it is much more likely to be found in the liver and there was no mention of contact with dogs.

Non-parasitic differential:

Polymyositis or Inclusion-body myositis: Definitely not something that you want to miss. I would want to check for any other symptoms (such as joint pain, lung problems, lab work of inflammatory markers and antibodies such as Anti-Jo or Anti-MI2). The muscle biopsy would absolutely help rule this out.

Hypothyroidism: Would be more likely to cause only weakness and not pain. More likely to have constipation instead of diarrhea.

Dehydration: There was a case over the summer of a kid playing basketball in the heat and having a severe breakdown of muscle. I would expect that this would be more of an acute problem, but I would keep it in mind.

Electrolyte abnormalities: In a similar vein as dehydration, I don’t think this would present as muscle pain, but I am uncertain of his diet and if he is getting everything he needs.

Vitamin D deficiency: This is a major contender. Severe vitamin D deficiency can cause myopathies in a few recorded cases. Living in Alaska, constantly covered up due to cold weather can lead to a severe deficiency. More worrisome is the deficiency of fruits and vegetables in his diet. He does eat fish though, which usually do have some vitamin D. I would nevertheless check his levels and start him on a supplement for general health if necessary.

Mitochondrial Myopathy: Unlikely to start this late, but I believe there have been a few cases. MELAS is uncommon and I would expect neurological sequelae, but I would keep it in mind especially without a family history.

Bacterial Abscess: I don’t recall the muscle pain being localized or generalized. A localized pain would make this more likely. I would get a blood culture, especially since his temperature is elevated.

SLE: Because it can present as anything.

A few more thoughts: Myotonic dystrophy type 2, sarcoidosis, acute infarction, and any drug-induced myopathy (although I know he is not on any drugs currently)

Sorry I got a little bit carried away. This was great practice for me and I hope you enjoy having a broad differential!


Iosif Davidov

MD Candidate at Hofstra Northwell SOM 2018

Heather writes:

Hello Dr.s.,

Taking a break from “grad studenting” and my normal day job (during which I have managed to turn my fingers purple with crystal violet) to share my thoughts on the latest case. This isn’t really a true differential, mostly what went through my head as I was listening.

Since this was an Alaska case salmon poisoning came to mind, but since the patient isn’t a canid and I am unaware of ocular involvement in salmon poisoning I decided to tentatively rule out  Neorickettsia helminthoeca.

I will also rule out Brucellosis since this is TWiP, but it did cross my mind because of the contact with game meat (I think this is more of a pig and ungulate disease though, not sure about bears). By the way: those of us who dress wild game usually wear armpit-high disposable gloves to lessen the chance of catching something fun like Brucella and Leptospira. I even bring a plastic apron out in the field with me.

We hunters (I say this like I have time to hunt while grad studenting, humph!) are also concerned about Dixon’s favorite parasite Trichinella. I personally do not eat bears, but we absolutely do NOT eat fresh wild pig meat in our household. It goes in the freezer first! Cooking wild game to “safe temperatures” can be hard because wild animals have a lot less fat and the meat can dry out much more quickly than that of domestic critters. Bacon is a commonly used adjuvant in this situation. Since Trichinella spiralis is the only parasite I can think of (by which I mean Google lazily) that has gastrointestinal, febrile, muscular, and ocular involvement and is known to be present in Alaska bears, that is my guess for this week.

I must now go run the gauntlet of potassium permanganate, potassium chromate, and silver nitrate and try not to turn myself any more interesting colors.



P.S. Can we please have a fungus case study? Fungal pathogens are technically parasitic IMO.

David writes:

Dear TWiP Amigos,

It is such an honor and pleasure to once again send in a guess for the case study. Me and my girlfriend were thrilled to hear our guess of African sleeping sickness was correct, and we hope the patient recovered quickly.

As for this week’s un-bear-ably parasitic case study, we would like to venture a guess that this patient has contracted a case of trichinosis caused by Trichinella in the bear meat. Although the hunter froze his bear meat, it takes a considerable amount of time to kill the nurse cells within the muscular tissue.  The correct method of destroying the parasite is to rather cook the meat at around 140 degrees F, but we are not sure of how high the temperature on the bear meat was when the hunter and his wife ate the meat.

The symptoms of diarrhea, muscle pain/tenderness, fever, and periorbital edema are all indicative of infection by Trichinella, as well as the results of the surge in eosinophils, elevated CK LDH levels are also consistent with trichinosis.

We would also like to correct a critical error in last week’s episode: Wilson was a volleyball, not a basketball!

Thank you again for the podcast, and keep on TwiPPing

~Dave P

Elise writes:

Dear TWIP Trifecta

How are you? Lower Manhattan in early March is windy with a steadily plunging temperature (currently 26 degrees F, -3.3 degrees C).

The Alaskan patient’s symptoms, when presented as a collective do seem to point in an extremely parasitic direction, especially in light of where he lives and his diet, however, in the interest of a differential diagnosis, I’ll cast a wider net.

His symptoms initially resemble a particularly horrible bout of food poisoning, but as the week progresses and his symptoms shift, they come to resemble the Most Likely Parasitic Suspect and  some other potentially more challenging infections.

The patient’s fever and severe myositis could indicate a viral or bacterial infection. Among the more frightening possibilities I thought about were Streptococcal myositis or Staphylococcus aureus myositis. These conditions progress extremely rapidly, though and the patient would probably not have survived long enough to wait for his wife to send him in for medical treatment as he did. Another possibility that I thought about was Lyme disease. Lyme symptoms, can often resemble the patient’s complaints (particularly if they’ve been combined with something like food poisoning).

Having said that, the Alaskan patient almost surely has become infested with Trichinella. We do know that he has a parasitic infection, but even without this prior knowledge, the progress of his symptoms: starting with nausea/abdominal pain and vomiting and progressing to intense muscle pain, periorbital edema, changes to his fingernails and eyes (that Dr. Griffin didn’t describe but which he did indicate were present when Dr. Despommier prodded about them), all suggest strongly that the bear meat wasn’t cooked quite as well as the patient had hoped. (A quick search revealed that bear meat in Alaska is a tremendous source of Trichinella.)

I do wonder why the patient’s wife is experiencing symptoms a week later than the patient. Does this couple regularly not cook its bear meat thoroughly, so that each ate a separate meal and became infected at different times? Does she have a different infection?

As always, thank you so much for your work and your wonderful podcast.


Eric writes:

Dear TWiP triumvirate, thank you for another fun case of the week. The signs and symptoms and patient history all seem to point trichinosis. Recent acquisition of fresh bear meat, check. Diarrhea, fever, abdominal pain, check. Edema around the eyes, check. You did want a differential, so one could also consider giardiasis or cryptosporidiosis, although these would not explain the wife also getting sick since she was not along on the expedition.

It is sunny and 60 degrees here in Seattle, a beautiful March day.

Anne writes:

TWIP 104

Hi TWIP team,

My thoughts for the case of the man from Anchorage with diarrhea followed by myalgia with eosinophilia

It is very hard not to leap straight to Trichinellosis (Trichinella spiralis infection) as so many things fit: consumption of black bear meat (albeit reportedly cooked, but adequately?); clinical course of diarrhea and vomiting (intestinal stage); followed by muscle pain, fever, and periorbital edema (myopathic stage); and blood work revealing elevated white cell count, eosinophilia, and elevated LDH and CK indicating muscle damage.

However, Daniel specifically asked for a differential list, rather than a single stab at a diagnosis.

Concentrating on a differential diagnosis list for eosinophilia as the differential diagnosis lists for diarrhea and vomiting, fever, elevation in white cell count, etc. seemed too non-specific to be useful/efficient.

I am ruling out the majority of the non-infectious causes of eosinophilia for the entirely inappropriate reason that the case was presented on TWIP. So I threw out: allergy, neoplastic disorders, hypereosinophilic syndrome and hypoadrenalism.

Infectious causes of eosinophilia


Strongyloides stercoralis hyperinfection GI signs, fever, abdominal pain but not usually myalgia

Toxocara visceral larval migrans –more likely to occur in children, can cause fever, malaise, nausea and vomiting, anorexia, and myositis, GI signs not predominating.

Hookworms- Necator americanus Abdominal pain, nausea, fever but generally no muscle pain/myalgia, outside of classic geographic range


Paragonimiasis-associated with ingestion of crabs, crayfish; pulmonary infection.

Nanophytes salmincola  trematode acquired through ingestion of salmon and related fish. Causes diarrhea, eosinophilia, nausea, vomiting and fatigue. In dogs, it is often fatal as the fluke carries the rickettsial organism, Neorickettsia helminthoeca.  This would have been a stronger differential if the patient had been a dog!


Cystoisospora belli GI signs but not muscle involvement, usually tropical

Sarcocystis spp can cause both intestinal and muscle syndromes in humans but not both, it seems and reports are primarily from Asia.


Coccidioidomycosis – Coccidioides immitis usually endemic to southwest US. Global warming hasn’t extended its range to Alaska yet?

Aspergillus, basidiobolomycosis, paracoccidioidomycosis, disseminated histoplasmosis, and cryptococcosis also associated with eosinophilia but not usually associated with GI signs and myalgia.

I ended up with Trichinella still being at the top of my list. I did find a reference that stated T. nativa in Alaskan bear and walrus meat is cold-resistant although this case did not hinge on whether or not the bear meat was frozen.

Anne Lewis, DVM, PhD

Beaverton, OR

David writes:

Dear Twiumvirate,

When I took Dr Racaniello’s Coursera Virology I course, I started listening to Twiv out of curiosity, it must have been around episode 238 around that time.  Contagion was almost instantaneous.

I am an electrical engineer, but have been working in education and software development ever since I graduated, and I have no biology degree.  Nevertheless, words like biochemistry or immunology always seemed surrounded by a glamorous mystic aura.  Having started with an old physiology textbook, a botany manual and a book on neuroscience some 5 years back, Twix really pushed me over the edge with its wide variety of science gems launched at us at a weekly basis.  I listen almost daily, generally at the end of the day, but also while doing small maintenance tasks in the house like painting.

After Twip75 (a glorious episode with Bobbi Pritt), something went wrong with my mail subscription, and I sadly regretted that Dr Depommier was probably busy traveling, while diving into Twim and going through the Twiv catalog.  Around new year I found out that Twip had just continued and upped the stakes by including diagnostics, and great was my joy.

While listening to the last 20 episodes, I felt taken aback and intimidated, even after listening to all Twip episodes and taking the coursera course on parasites.  Even professionals (sometimes) get it wrong, and I felt powerless.  This week, after listening to some eosinophil related episodes, I decided that I would have no rest until I got to the bottom of this.

So here is my diagnosis:

I go with trichinosis as the diagnosis for the case, because it fits so well: the bear meat was a give away to begin with, recalling the stories of polar explorers when Trichinella was initially discussed.

I actually started my diagnosis with eosinophilia, because I am practically clueless at all how one should diagnose a patient. Keeping in mind Dr Griffin’s warning that Twip could also include non parasitic diseases, I checked the non parasite options first:

I found lots of allergies which I discarded because of the generally very healthy state of the individual, and the fact his wife got infected too excluded these. Then there were the eosinophilic primary diseases, but these I also excluded because there obviously was something else going on. Tumors like leukemia and lymphoma also got excluded based on their non infectious nature. For the rest, as the patient was HIV negative and the other options seemed rather far fetched, I turned to the main dish: the parasites.

The high eosinophil count excluded most non helminths, except for Dientamoeba fragilis, Isospora belli and Sarcocystis. Dientamoeba appears to contaminate through water which the man drinks from the stream, so this was an option, as it causes diarrhea and fever, but it seems to focus mainly on lower intestine, while the victim also displays elevated muscle enzymes pointing towards tissue breakdown

Isosporiasis is less realistic as it transmits fecal to oral and mostly attacks the immuno compromised.

Sarcocystis appears to be an option.  It is caused by undercooked meat and leads to diarrhea and vomiting, and wiki tells me it also has elevated CK levels associated with it.  However, the time of the initial sickness is only 36 hours, while it lasted a week for our poor hunter.

Then for the (most common) helminths

Ascariasis, Trichuriasis, Strongyloidiasis and tapeworms do not seem to match the symptoms well enough. Filariasis could be excluded because we are talking Alaska, as well as Schistosoma.  I must say I did not check geographical distributions thoroughly, mainly because I could not find them but these are tropical for all I know.

Then there was the wiki on trichinosis, which had it all: the edema around the eyes, the muscle pains and muscle weakness.  Larvae travel to the myocardium and to the skeletal muscles, this should explain the tissue breakdown leading to CK.  Conjunctivitis and retinal hemorrhages featured among symptoms, so that explained why Dickson asked about it.

The CDC image for Trichinella spiralis nicely includes the black bear.

I must say it is quite a thrill to have more than an educated guess, and although I may be wrong, I am just happy that I managed to wade through the symptoms to come up with a reasonable diagnosis.

I guess the diagnosis can be confirmed by using a microscope to have a look at the larvae.

Treatment should probably be the miracle drug  albendazole, or mebendazole.  Prednisone is mentioned to help relieve muscle pain.

So, here is my guess, I hope I did not make wrong inferences, but the case seems to have trichinella written all over it.

It is a pleasant 33 C in Jinotepe, Nicaragua, and I send you my regards, thanking you for all these wonderful episodes and those still to come.




I was initially thrown off by a document I examined “Intestinal parasite guidelnes for domestic medical examination for newly arrived refugees” of the CDC,, which does not even mention trichinella as a parasite causing eosinophilia.  I still wonder why that is.  Is trichinella not an intestinal parasite?  The larvae do hatch in the small intestine… Or is it because of the geographic distribution, with the US rarely receiving refugees with trichinella?


Johnye writes:

Dear TWiPersonae,

Ran across this and thought of you. I am trusting Ted-Ed to have had their science facts checked and verified. PERSONIFICATION ALERT!!! Note: There has been shameless and wanton projection of human behavior and intent on the viruses and parasites portrayed in this video.


Alexa writes:

Hi there,

I was referred to you guys from a listener and fan. I was wondering if you could tell me anything about Chagas disease and the Triatominae insects that carry it?

I rescued a pregnant dog from a shelter, who had 4 puppies. 2 of those puppies died suddenly (no symptoms or warning), one was only 8 weeks old and one was just over 1 year. I had the other 2 pups (now in other homes) taken to a cardiologist to see what we could learn, and one of the siblings showed some minor heart abnormalities… I’m in Texas, so I’m assuming the cardiologist knew from experience what this looked like, and had that dog tested for Chagas. The test, tragically, came back positive.  

I’m working on getting the momma dog (who I still have) and the remaining puppy tested, though based on what we know it is strongly believed that mom was the vector and passed the disease in utero to the puppies.

As I understand it, there is no “cure” for Chagas in dogs… only experimental treatments, which I am pursuing. I wanted to know if you knew of anything regarding drugs or treatments that are being tested besides the “standard” drugs like benznidazole or nifurtimox (which are not available for veterinary use unless they are approved by the CDC for “investigational protocols”).

I was also wondering if you know anything further about transmission? I was told by my vets that dog-to-people transmission has never been documented and extraordinarily unlikely. I was also told there were no known cases of dog-to-dog transmission outside of a pregnant mother to pups… but is there any actual data on this? Would it be POSSIBLE? I know it can be transferred if people eat contaminated animals, or through blood transfusion… but what about casual contact with animal blood? I helped this dog give birth to her puppies, I have had contact with her blood… and I’m sure at one point or another, the other dogs in my house (unrelated to her) have too.

I really appreciate any information you can share. This is devastating to me… the first puppy died while still in my care, and the second was actually a puppy I ended up keeping… I love all of these dogs tremendously, and am terrified of losing them.

Thank you so much,


WilsonEsper writes:

BTW, huge mistake in TWiP 104: La maladie du sommeil.

Wilson was born of a volleyball, not a basketball as mentioned. Picture attached.

I could tell it was a volleyball during the movie, since it is a world recognized sport, as opposed to some strange sports you play in America.


David writes:

Was just listening to TWIP104 again, and I overheard Dr Libman mentioning that Belgians worried about the health state of their slaves because sleeping sickness would not get them safely across the ocean.

Being a Belgian by birth and having studied the history of the Congo somewhat extensively, I need to point out that this is not quite correct.  Slavery had already been abolished in the US 20 years before Leopold II surreptitiously snatched the huge territory of the Congo from under the nose of the British and French contenders. “Freestate” Congo remained personal property of Leopold II until 1908.

No slaves were exported in these years, although the period was particularly brutal.  Leopold II was desperate to recover his investments, and the few mercenaries on the ground who oversaw operations did everything necessary to increase rubber production – the bubble commodity of the era when bicycles were just gaining momentum.  They famously cut off hands of natives resisting forced labour.

I know it’s a detail and that science and not history is the protagonist in Twip, but this seemed like a flagrant misconception.

Kind regards,


Michael Libman writes:

My bad luck to have a listener interested in both parasitology and Belgian colonial history. So my apologies to him, and to Belgians in general for the error he points out. While the brutality inflicted on local workers under Leopold, particularly in the rubber and mining industries, has been well described, accusing the Belgians of complicity in the slave trade was certainly incorrect.

The relationship of colonial era health care and trypanosomiasis is still quite interesting. It is clear that at the start of the 20th century, as French and Belgian health care workers established themselves throughout West Africa, they found that trypanosomiasis was rampant, and decimating the indigenous population. The reasons for this are speculative, but likely involve earlier population movements related to both the slave trade and developments in the forestry, rubber, and agricultural colonial industries. We presume that this led to movement of non-immunes into endemic areas, and perhaps enabled spread of tse-tse flies into new habitats.

The colonial powers, first France, and later Belgium, became interested in mass control programs primarily as a way of protecting their labour force, but also to protect expatriate Europeans. Among the first was a French military doctor named Jamot, who made an incredible contribution to controlling this disease in French Central Africa and Cameroon using injectable arsenicals. The medication sometimes killed individual patients, but was very successful at reducing the human reservoir. Between 1917-19, Janot examined almost 90,000 individuals, diagnosed and treated over 5000 cases, all with exactly 3 microscopes and 6 syringes. His team travelled largely by foot from village to village. Some of his European colleagues succumbed to the disease, and published the progression of their own symptoms in journals.

The Belgians were a bit less organized in this respect, and trypanosomiasis control was undertaken by physicians working not only for the government, but also for the private industries, missionaries, and philanthropies. From 1910 to 1940, the number of doctors in the Belgian Congo increased from 47 to 302, with particular directives for treating trypanosomiasis as well as yaws and syphilis.

After the war, Belgium, perhaps moved by a sense of moral debt towards the Congo, invested heavily in health care, with over 10% of the colonial budget dedicated to this area. In 1958, the colony had 2815 health institutions of various types, with 85,000 hospital beds, probably more than the rest of colonial Africa combined.

For those interested, I actually stole much of the above information from a fascinating book, “The Origins of AIDS” by Jacques Pepin. Indeed, the study of parasitology is intimately intertwined with human history… Thanks again to the listener who gave me another opportunity to prattle on…


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