Case guesses:

Shelby writes:

Hello from Nashville!

Currently its sunny and 16° C.

My guess diagnosis for the long haul trucker is cryptosporidosis caused by Cryptosporidium parvum or C. hominis which can cause the massive fluid loss reported. The patient most likely ingested oocytes from fecally contaminated food or water.

I just finished my registration for the next semester at MTSU and am very excited to say that I’ve enrolled in a parasitology course looking forward to using the podcast as a resource and inspiration for my studies.

Have a great day,


Brian writes:

Hello TWiPanosome docs! After the last paper I couldn’t help myself to try that one out. First off, I must apologize for my last letter, I must confess that I was a bit embarrassed at how poorly written it was.  I am still at work, still on my smartphone but I have at least stopped long enough to write this email.

I think the 48 yo male from Mali suffers from cryptosporidiosis. I did a quick search online and there is a paper ( a little dated) from 1997 that I found on Google Scholar that references Enterocytozoon bieneusi also, (I think this is a parasitic fungal species) but another study showed higher percentages of C. parvum in this region among patients with HIV/AIDS.

Thank you for suffering through my last guess and I hope that autocorrect didn’t outrun my fingers this time. Thank you for the shows I love them all and always look forward to the next one.

I didn’t get into the description of my guess because you have already provided pathology and usually give a good brief lesson after the reveal so I’ll let others ramble on about such things. Thanks again, hope I’m right.

Thank you,


Iosif writes:

Dear Twip team.

It is ironic that you asked me to make sure that my classmates had access to the sixth edition of Parasitic Diseases since I already handed it out! The second year medical students recently had their parasite lecture and so I put up the PDF of the textbook on Facebook so that anyone that was interested could look up more information. I made a selling point that all of the pictures were in color! On behalf of the medical school I do thank you for the free access.

As for the differential for our patient, my number one diagnosis would be a cryptosporidium infection. While cryptosporidium can be well managed or even asymptomatic in an immunocompetent patient, in immunocompromised patients it can lead to severe diarrhea and has a high mortality rate. In this patient, he may be severely dehydrated by the vast amounts of fluid that have been lost leading to activation of the sympathetic system in order to compensate. His BP being 80/40 is particularly concerning. I would  put in two large bore IVs immediately and give 2 liters of NS or LR before doing anything else. Next I would get a CBC to see if there are any electrolyte abnormalities from the severe diarrhea and try to replete accordingly. A diagnosis could be obtained via stool culture or PCR/immunoassays if they are available. I would also want to check for any other infections that may also be present. Particularly Pneumocystis jiroveci, MAI, or tuberculosis since the patient is breathing fairly rapidly and I don’t know what his breath sounds are like.

Treatment for cryptosporidium for this patient would require the initiation of HAART therapy so that his own immune system would start to fight back. While nitazoxanide and paromomycin seem to help immunocompetent patients, it does not offer much benefit to immunocompromised patients.

If I may pose a question to Dr. Griffin; what is the chance of developing immune reconstitution inflammatory syndrome in this patient? If we find another infection, should we treat it first, then reinstate HAART therapy? Basically I am trying to find out if IRIS is worse than having the diarrhea or the other way around.


Iosif Davidov

Hofstra SOM class of 2018

P.S. In the case, it was mentioned that the patient had around 3L of diarrhea a day. In the textbook, it says that immunocompromised patients may get over 3L of diarrhea per day. Coincidence?

Fredrik writes:


Getting “a blooded tooth” (Swedish expression for acquiring a craving after having a first taste of something) from last week’s contribution I will venture another guess.

First of all his hiv subtype of course suggests he contracted the virus in the us rather than Africa which is reasonable to assume from his history. It would be reasonable to think that he contracted the parasite in Mali though, via contaminated food e.g. The state of his anal cancer indicates that he is not particularly prone to seeking medical advice, you would think. Tracking his sexual contacts will probably be an arduous process, given his occupation and hardly recent infection.

Obviously there are several parasites could cause diarrhea in a severely immunocompromised patient. I’m gonna go with the classics however and guess cryptosporidium which could cause this clinical manifestation with profuse, I’m assuming, secretory diarrhea. No colitis symptoms (blood and pain mainly). When it comes to diagnosis, stool would provide it. In our lab you would have to ask specifically though, I think it may be a pcr test. I’m guessing O&P might be challenging with the volumes of sample matter but to test for coinfections of both eu- and prokaryote kind would be wise as they may contribute to symptoms and may be possible to treat etiologically. If the diagnosis is correct his diarrhea may be severe and prolonged.

This is an intensive care patient showing signs of hypovolemic shock so prompt volume expansion is indicated before anything else, with your preferred crystalloid. Once he is in the hands of the icu doctors I would concentrate on getting him on an appropriate antiretroviral regimen as getting his CD4-count up >200 is what could possibly save him in the long run as the pathogen itself is virtually untreatable but self-limiting in a competent host.


Pediatrician in training at University hospital of northern Sweden in Umeå

Zachary writes:

Dear TWiP triumvirate,

My name is Zac and I am a second-year medical student at the Medical College of Wisconsin in Milwaukee, WI. I have been listening to the TWiX podcasts for nearly 6 years but have been part of the silent majority; however, as a Milwaukee resident, it is time to put in my two cents. There wasn’t a lot of data to go on but my tentative Assessment and Plan is as follows:

This is a 48-year-old male, who was recently diagnosed as HIV positive with a CD4+ count less than 100, presenting with diarrhea, cachexia, fever, hypotension, tachycardia, and tachypnea. My differential diagnosis includes diarrhea secondary parasitic etiologies (e.g. Cryptosporidium, Giardia, Entamoeba, Cystoisospora, or Cyclospora); fungal etiologies (e.g. microsporidian spp.); viral etiologies (HIV, CMV, HSV, or HHV-8); bacterial etiologies (e.g. Mycobacterium avium complex (MAC), Vibrio cholerae, C. diff., E. coli, Salmonella, Shigella, or Campylobacter); or non-infectious etiologies (e.g. lymphoma or Inflammatory Bowel Disease). Because the show’s name is This Week in Parasitism, the patient’s immunocompromised status, the severe watery diarrhea, the weight loss, and my Milwaukeean intuition, Cryptosporidiosis is suggested.

Fluid and electrolyte management should be initiated as well as HAART. The stool should be examined via cultures, toxin assays, and O&Ps. Staining techniques can reveal the presence of cryptosporidium, as well as other parasites.  If the patient does in fact have Cryptosporidiosis, and the medication is tolerated by the patient, nitazoxanide can be initiated.

Although I am too young to remember the Cryptosporidiosis outbreak in Milwaukee, WI, I am sure Dickson can enlighten us all (we are briefly mentioned in your book)!

Thanks for all of your hard work,

Zac T.

Wink writes:

Dear TWIP Professors,

As it says in the 6th Edition, “diarrhea may be severe with several liters per day of diarrhea” due to cryptosporidiosis. That’s my guess. I have seen many advanced HIV patients waste to a marked degree, as did your patient, and Cryptosporidium is often their presenting opportunistic infection. My only reservation is that in HIV severe infections usually occur at a lower CD4 count and improve when it comes up to 75 CD4/ml. I wonder if our truck driver ingested a hefty dose of cysts in his travels.

Wink Weinberg


Suzanne writes:

Dear Professors:

A few months ago, I finally listened to TWIP after much encouragement from my grown son.  I’m hooked.  I started from the beginning and just finished episode 41. However, I was curious about the new episodes.  So I skipped ahead and just listened to the last few.  It was exciting to find out that the 6th edition Parasitic Diseases is online at my fingertips.  The case studies presented by Dr. Griffin are thought provoking.  

In the 1980s and early 1990s, I attended medical school and completed internal medicine training.  Sadly, I witnessed many horrible infections that overwhelmed AIDs patients.  So hearing this case in TWIP #120 brought back memories.  My first differential included: Cryptosporidium parvum, Giardia lamblia, and Entamoeba histolytica.  The poor man seemed very ill and had a very low T cell count.  I am surprised that his diarrhea wasn’t bloody.  I think that he most likely had amebic dysentery with Entamoeba histolytica.  It can cause a severe diarrhea and abdominal pain.  Plus, the rectal mass was not a cancer but it was an ameboma.  He had direct spread to the perianal area and had cutaneous amebiasis.  I bet you saw cysts or trophazoites in his stool or in that fungating mass.  Hope the poor man survived.  

Last month, I completed my recertification boards (which we do every 10 years).  It was an all day test about internal medicine knowledge.  Out of all those questions, I believe there were only 3 parasite questions.  Two were about AIDs patients with diarrhea.  The other question stumped me.  My brain froze.  The question started with a case study about a 30 year old female who lives in America but went to visit her family in Korea.  She stayed there for a few weeks.  The case mentioned that she had eaten lots of raw fish while visiting her family.  When she was back in America, she had abdominal pain.  An ultrasound of her abdomen showed a large thick walled cyst in the liver.  The question was “what parasite caused this?”  It was a multiple choice question and there were 5 different parasites to choose from.   All I could think about was that Dr. Despommier would be so disappointed in me for not knowing the answer.  Why did the history point out that she ate all that raw fish in Korea?  Can liver flukes cause a thick walled cyst?  I thought they went to the bile duct.  I knew that Entamoeba could make a nasty cyst but is it thick walled? I struggled with that stupid question for so long that I confused myself. Dr. Despommier, can you tell me what parasites cause a thick walled liver cyst?  Please help me put this case at rest.

Thank you for presenting this material in such an entertaining way.  It has helped me remember old information from medical school.  Furthermore, I learn so many things about the world from your brilliant brains.  Please keep doing what you are doing.  

The fall weather here in Idaho has been wonderful.

Niall writes:

Hi there! I’m a fly fisherman from Montana and you may remember several years ago when I asked to learn more about Whirling Disease in trout. Well, unfortunately another parasitic disease has popped up in the state. Most of the Yellowstone River has been closed to recreation due to a massive whitefish die-off caused by Proliferative Kidney Disease. It is apparently caused by Tetracapsuloides bryosalmonae and more than 2,000 fish have been found dead. If you could tell us a little about this parasite, that’d be awesome!

As a side note, Dr. Racaniello, it was an honor to meet you last time you were at RML! Thanks all for what you do!


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