Case guesses:

Erik writes:

Hello TWiP crew,

This is my first time writing in with a guess for the case of the week. I felt compelled to write in because it turned out that my guess for last episode’s case was correct and, on hearing this week’s case, I felt that I had a pretty strong guess (without even having to utilize Professor Google!).

The staggeringly high eosinophil count in the patients immediately made me think that this is likely an infection with some parasitic worm or other. The symptoms imply that the infection is in the GI tract and, while I admit the mention of raw fish consumption could be a red herring (pun intended), the symptoms associated with the parasite that I’m guessing are too close a match for me to think it’s anything else.

I think the patients have a case of anisakiasis. After double-checking on, anisakiasis symptoms include: abdominal pain, nausea, abdominal distention, and diarrhea. Unfortunately I can’t guess any particular species because I don’t know enough about this parasite. I don’t think I have any good differential diagnosis either.

Hope I got it right on my first time writing in!! Maybe I’ll submit guesses more often!

Wink writes:

TWIP Professors,

My guess this week is gnathostomiasis. I think it can be found in Australia on freshwater fish. For the first few weeks of infection you get GI symptoms. Later, you may get skin swellings and errant parasite distribution.

Wink Weinberg

Jeff writes:

Dear TWIP Doctors,

A sunny 65F in South San Francisco today.  An interesting case as most of the family was infected.  When thinking about parasitic infections from fish usually you think of Anisakis simplex for salt water fish or Diphyllobothrium latum for fresh water fish.  The clinical presentation isn’t consistent with Anisakiasis so I would rule that out based on the presentation.  Diphyllobothriasis is more consistent clinically but there are a few things which make this also unlikely.  A number of cases of diphyllobothriasis are asymptomatic and most of the family members have disease.  Furthermore, Daniel didn’t mention the presence of anemia in any of the family members, which is common in cases of diphyllobothriasis and resembles pernicious anemia.

So, I am really go out on a limb here and guess Giardia duodenalis as the infective agent as it is consistent with the clinical presentation and I have found some evidence of this being important in the region.  I ran across this reference in my research and thought it was pretty interesting:  International Journal for Parasitology 40 (2010) 779–785.


Jeff Fairman, Ph.D.

Vice President, Research

SutroVax, Inc.

South San Francisco, CA

Michelle writes:

Dear TWIP Hosts,

I am a long time listener, but first time writer. I am an Assistant Professor of Microbiology at a medical school in the Pacific Northwest. Although parasites are my specialty (especially schistosomes), I do not get to lecture about them very often. Unfortunately, our curriculum is limited when it comes to Eukaryotic pathogens. I love your idea of giving out your textbook to all medical students—the trick is getting them to actually read it as students these days appear to be afraid of textbooks.

For the family in Australia: Eosinophilia plus a range of symptoms from asymptomatic to abdominal distention to severe diarrhea and cramping suggests an intestinal helminth. The clue of raw fish connecting the cases leads to the hypothesis of infection with the broad fish tapeworm or Diphyllobothriasis. Although this parasite is typically thought of as having a circumpolar distribution, further research on Google Scholar indicates that the distribution of this disease appears to be expanding. In fact, it is included in the CDC’s Emerging Infectious Diseases journal (Kutcha et al 2015). A paper from 2009 (Scholz et al 2009) reports “no reliable recent reports” in Australia; however, there is a recent case report from Australia of a 3 year old infected with the tapeworm, Adenocephalus pacificus (Moore et al 2016). Infection was presumably acquired from eating raw marine fish caught by his father off the southern coast of Australia. The tapeworm, Adenocephalus pacificus was known to be endemic to Australian territories within pinnipeds for quite some time, which suggests that recent infections have more to do with changing dietary habits rather than imported parasites, although imported cases have been documented in other areas (from South America to Spain).

There are several species of Diphyllobothrium and Adenocephalus and their life cycles vary somewhat, but the general pattern involves three hosts, a copepod intermediate host, a fish intermediate host, and a fish eating mammal definitive host. They do not seem to be very specific to their mammal or fish hosts. The tapeworms are reproductive adults within the intestine of fish eating mammals. They release eggs with the host’s feces into the water and when the eggs are fully developed, they hatch, releasing a ciliated “coracidium”. The coracidium is eaten by a copepod (small crustacean), and develops into a procercoid within the body cavity. When an appropriate fish host eats the infected copepod, the parasite develops into a pleurocercoid. Several marine, brackish and freshwater fish species can serve as hosts for the different species of these tapeworms with salmonids being a common source of human infection. When the mammal eats the pleurocercoid in the fish musculature, the tapeworm establishes in the intestine and matures into an adult.

Symptoms caused by infection with these worms are variable and depends on the number of tapeworms present, the individual’s response to infection, and probably characteristics of the tapeworms (although this is not well understood). Many infections are asymptomatic, and symptomatic ones include diarrhea, abdominal discomfort or pain, nausea, vomiting, and bloating. Diphyllobothriasis is also classically associated with vitamin B12 deficiency and thus megaloblastic anemia, although this presentation is apparently rare and may not be caused by all species (Kutcha et al 2015).

For diagnosis, sedimentation of feces should reveal characteristic eggs. The eggs do not float well when zinc sulfate or a sugar solution is used to concentrate the eggs, thus sedimentation techniques are necessary. Egg shape varies somewhat among the species but they are about 40 x 60 micrometers, oval to round in shape, operculate, and have a knob or small protrusion at the abopercular end. Chains of the proglottids may also be found in a macroscopic examination fecal samples. The proglottis are more wide than long, hence the name “broad fish tapeworm”.  Identification of the species can be accomplished through DNA sequencing.

Praziquantel or niclosimide can be used for treatment.

Keep the cases coming.

From the ultra-rainy (even for us) Pacific Northwest,


Kutcha, R. et al 2015. Pacific Broad Tapeworm Adenocephalus pacificus as a causative agent of globally reemerging diphyllobothriosis. Emerging Infectious Diseases 21 (10).

More, C.V. et al 2016. Rare human infection with Pacific Broad Tapeworm Adenocephalus pacificus, Australia. Emerging Infectious Diseases 22 (8): 1510-1512.

Scholz et al 2009. “Update on the Human Broad Tapeworm (Genus Diphyllobothrium), Including Clinical Relevance” Clinical Reviews in Microbiology 2009 22(1): 146-160.

Michelle Steinauer, Ph.D.

Assistant Professor of Microbiology

Western University of Health Sciences

Lebanon, OR

Sofie writes:

Dear Twip-Team,

Thank you for the story about Schistosomiasis and how they eradicated it in Japan. I found it very interesting.

To answer your question Dickson, I graduated med school in 2011 from Aarhus University Faculty of Health

Unfortunately I don’t remember who of my microbiology teachers revealed the story about Katayama fever and Schistosomiasis in Japan, but obviously it made an impression.

Have a very nice day and thanks again for expanding my horizon.


Derek writes:


There’s a paper out in Nature Communications that would be appropriate for either TWIV or TWIP, but probably most so for TWIP. “Eukaryotic association module in phage WO genomes from Wolbachia”

This is fascinating, and as far as I know the first time a phage has been shown to carry around animal DNA. In this case the DNA for the black widow spider venom! Would be great to hear your take on this work.

Also, when I went to your website to remind myself of your email address, the entire page was shortly taken over by an ad for a virus removal company that tried very hard to raise popups preventing me from closing the page. I don’t know if your website is a wordpress site, but it is very reminiscent of an attack on a site I maintain that happened a year or so ago.

Keep up the great podcasts! Thanks,


Anthony writes:

Back in the recession of the early-’90s, the tide of yuppies on the Jersey City waterfront for a while reversed.  Left behind were here and there some yessies (Young Educated Scrounges), myself among them.  Not far away from where I lived on Warren St by Sussex, there was a block square ditch from construction suspended due to the inclement economy.  (the Onyx site) The fallow land had become marsh.  After the spring rains, each night from the muddy water came clouds of mosquitoes and the unbelievably loud chorus of mobs of toads mating.  Sleep was difficult, for even with screens mosquitoes found their way into the apartment.   Plus, even a block away and four stories up, the noise from the amphibians kept me awake.  

The thought came to me while staring at the ceiling one night that the Biblical plague of frogs must have been Malaria.  The Egyptians associated the unusual sound with the disease.  What I couldn’t understand was why they didn’t blame the mosquitoes.  Prof. Despommier seems have to answered that.  When discussing the culturing of mosquitoes he mentioned that the “volunteer” feeders became desensitized to the bites.  

– – –

In a discussion of Toxoplasma, there was some wondering on what attraction cat faeces held for mice.  Many years ago when I’d go walking in the woods I’d every so often see animal skulls.  I never saw a carcass or a skeleton.  My surmise was that when an animal died scavengers made quick work of everything including the bones.  The skull seemingly was too hard for small teeth to dent and so was the only thing that remained.

Domestic cats tend to catch small rodents birds.  The felines consume these by using their jaws to crunch the body and so break the bones.  They then swallow everything in chunks, leaving just the head or wings.  The undigested bones are passed.  Perhaps this calcium source is what interests the mice?


Bryce writes:

TWiP Triad,

This case comes at a great time since I have a test this Friday about hemolysis and other blood disorders.  Given the lower levels of hemoglobin and mean cellular volume as well as the slightly elevated bilirubin levels, this woman is presenting microcytic anemia.  Her symptoms appear to follow a cyclical fashion, which, combined with the anemia suggests Plasmodium to be the diagnosis.  To parse out the specific species, I am sure a PCR could be ordered.  However, by following the nature of her fever, the patient appears to be infected with either P. vivax or P. ovale as these parasites give a spike in fever, corresponding with the rupture of the schizont, followed by a couple of days of rest while the parasite infects other RBC’s to continue the cycle.  P. falciparium, on the other hand, undergoes continuous schizont rupture leading to a fever that never breaks.  Additionally, these two species (P. vivax and P. ovale) are associated with an enlarged spleen.  To treat the malaria, cholorquine to eliminate circulating parasite should be administered in addition to primaquine to remove the hypnozoite that can cause a relapse infection.  Thank you for the weekly (well almost weekly) study material through the case studies! Hopefully I did not get this one wrong otherwise that does not bode well for my test.



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