Case guesses:

Iosif writes:

Dear Twip hosts.

Since Dr. Griffin stated he wanted a full workup and not just parasites, let’s start with the non-parasites first:

Cholera – This is listed on the CDC as a possible infection in Cameroon; however, our patient’s diarrhea was described as intermittent and cholera is generally a voluminous, watery and non-intermittent diarrhea. I would also expect some symptoms of dehydration or electrolyte disturbance if this has been going on for a few weeks.

E. Coli – Depending on the strain, the diarrhea could be watery or bloody. Most likely she may have EPEC or EIEC. EPEC is also more prevalent in the pediatric population and she may have gotten it from somehow from the school.

Leptospirosis – There are several cases within Cameroon, but there should definitely be more symptoms that what she is presenting with. At the very least I would expect a fever and headache and worst case scenario full blown Weil’s disease.

Salmonella – Another possible cause, but again usually with some more symptoms like fever, nausea or vomiting.

Campylobacter – May cause watery diarrhea or bloody diarrhea. I don’t think the symptoms would last for over a week though in someone not immuno-compromised. I would watch out for Guillain-Barre just in case though.

Adenovirus – Another possibility due to the proximity to children. Also unlikely from the lack of other symptoms such as some rhinorrhea, conjunctivitis or sore throat.

Rotavirus – I assume she has been vaccinated and so this is very low on my list.


Cryptosporidium parvum – Can be obtained from contaminated water. Could result in a diarrhea that last for about 2 weeks that would improve on its own unless the host is immuno-compromised.

Giardi lamblia – Definitely a possibility. I would expect more fatty and foul smelling stools though.

Entamoeba histolytica/dispar – One of the higher diagnosis on the list. Can lead to diarrhea that lasts for weeks to months. Although there may be blood in the stool it wouldn’t be visible to the naked eye and would need to be tested.

Cyclospora Cayetanensis – Especially since she has admitted to eating local fruits and vegetables.

In terms of treatment, I would order a stool ova and parasites be sent and also obtain a CBC to determine if there is any significant blood loss that may be going on or if there is an elevated white count. I would also make sure the patient is hydrated if there is any reason to suspect a significant fluid loss. Lastly, I may order NAAT for several of the parasites like cryptosporidium if the stool O&P is negative and the patient continued to worsen.


Iosif Davidov

Suellen writes:

I am so excited to finally be able to submit my first-ever possible diagnosis! It may be right, it may be wrong, but I don’t care cuz it was fun to research!

This is for the 24-year old Peace Corps worker who has intermittent diarrhea, loose stools, and abdominal discomfort, with no fever or rash.

I actually made a list of possibilities, 10 of them, and then went through them and finally narrowed it down to Ascariasis, caused by Ascaris lumbricoides, a species of roundworm. This is a very common parasite in that part of the world, and people in the early stages of infection often have few or no symptoms. I also picked this because it’s a common disease in children, who contaminate their hands and then stick those little paws in their mouths and infect themselves. As a teacher, our Peace Corps worker is in regular contact with these little infectious disease incubators, and so it seems likely that she may have become infected that way — or, through food or water contaminated with fecal matter.

The sources I checked say that, in the early stages of the infection, the worms may be visible in the stool, so if possible I would try to either get a stool sample or ask our intrepid Peace Corps worker to take a good, close look at that loose stool of hers. In later stages, the worm moves to the lungs and throat, and may cause vomiting or even cause the patient to cough up worms (ugh!), but she’s not at this stage yet.

Treatment? Well, I’m no doctor, but I googled it (just as good, right?) and the common treatments are Albendazole, Ivermectin (which we give our horses to treat worms, too!) , and Mebendazol.

That was fun! And a nice break from my long workday here, where I’m an IT professional (Oracle database administrator) for a big health care company. Even if I’m wrong, it was a nice exercise, and I’ll try again next week.

Thanks so much for TWIP — and all its siblings! Please keep up the good science, we really need it now!


Weather in Alpharetta, GA — sunny and 54 degrees F.

Dan writes:

Dear TWiP Trinity

I’m writing again from London where it’s a dull, wet 6 degrees Celsius. Thanks for an always-entertaining podcast and another fascinating case.

For the 24-year old Peace Corps volunteer with diarrhoea, abdominal discomfort and malaise lasting a few weeks, the differential diagnosis is pretty broad.

Many protozoa including Entamoeba, Giardia, Cryptosporidium and Cyclospora could be causing this. My first thought was Giardia lamblia – a common cause of prolonged diarrhoea in this population. Close contact with children (who could be asymptomatic carriers) and animals are risk factors.

What would I advise if I took the call? Volunteers may have been prescribed ciprofloxacin or azithromycin for ‘standby’ treatment of bacterial diarrhoea (which she may have taken) but this is unlikely to be effective. It’s not urgent, but she would need to have a clinical assessment in a reliable clinic, which may mean taking a trip to the Capital.

Daniel told us that a pathogen was confirmed in the lab. The first-line diagnostic test is stool microscopy – ideally done by a competent lab technician. I’m not sure what level of testing is available – does Yaoundé have a Pasteur Institute? Giardia can be hard to find on microscopy and multiple samples may be necessary. Antigen tests are more sensitive. Diagnosis of Entamoeba histolytica can also be challenging as cysts of non-pathogenic species look identical. ELISA-based adhesin testing (if available) can specifically detect pathogenic E. histolytica.

Cryptosporidium, Cyclospora and other opportunistic protozoa would be possibilities, but they rarely cause persistent symptoms in an immunocompetent host. She may well have a mixed infection after 5 months in the field.

Moving on to helminths, Strongyloides is not a common cause of persistent diarrhoea, but I would test for this if she had eosinophilia. Do the Peace Corps routinely ‘deworm’ with albendazole?

Anyway… these are my initial thoughts based on the limited info provided! As always I look forward to hearing your collective wisdom…

best regards


Steve writes:

Greetings Twipastafarians!

Okay, that was probably stretching the TWIP wordplay a bit far.

I got behind on my TWIP episodes and have only now caught up. I’ll just dive right in to our case study involving our Peace Corp worker in Cameroon.

There are so many possibilities here. I would order stool studies for giardia and cryptosporidium as well as a stool culture and oval and parasite exams.  This should cover most of the usual non-viral suspects.

I am unaware of any viruses that would cause 3 weeks of diarrhea, so I would tend to assume bacterial or parasites to be the culprits.  And, of course, one cannot rule out a mixed infection.

Given the symptoms, I’m inclined toward giardiasis, which presents as intermittent diarrhea in many individuals.  Other possible suspects include ascaris lumbricoides or tapeworms, though in the latter case the lack of proglottids tends to make me rule that out.  Of course, hookworms and other helminths are a possibility, plus a myriad other parasites I’m probably not considering at the moment. I have to confess that I don’t have the time to do a proper deep dive into my free pdf of Parasitic Diseases, sixth edition, this morning so I’m primarily relying on my own memory.

Water contamination is the most likely source. However, since she is teaching young children, contamination from the children is also highly possible. As my wife, a teacher, can attest, children are not notorious for sanitary behaviors.

We just got over a series of storms in the eastern Sierra making this the second wettest January on record. Hopefully this means our drought concerns are over in California.

Best wishes,


Thomas writes:

While listening to your discussion of Naeglaria fowlerii, I looked in both the 5th and 6th versions of Parasitic Diseases and found the word “cribiform”. Alas the word does not exist, although “cribriform” does. I checked Webster’s 3rd International dictionary and used  to search the Internet to be sure. They both indicate “cribriform” is correct. I only found this error because I look up words whose meanings I don’t know.

I especially enjoy your episodes where people write in with their guess at the cause of some medical condition. Other than an interest in medicine, especially infectious diseases, and now parasitic diseases, I have no medical background. During my working years I was in the field of intelligence.

As I am almost 80 now, my short term memory is infuriatingly patchy. I am glad Dickson has escaped this condition. Still I try to learn and enjoy what I can.

I bought a new Nikon medical microscope and a lot of histology and histopathology microscope slides. The Youtube has presentations on almost every histology slide I have, so I can look at what they show and see how closely it resembles what I see, as well as learn about the subject of the slide. My microscope does not have “darkfield” or “phase contrast” capabilities but I still can enjoy looking at protists from a nearby pond. When I was in my twenties, I bought a superb interference phase contrast Nikon in Tokyo, where I was stationed with the USAF. I remember how the water was a lovely blue and internal components of the cell were often ruby or gold in color. I haven’t found any such microscopes available currently. Any suggestions? I would spend up to $6,000 for such a microscope.

Thanks again for presenting material that is of interest to me. When I run out of parasites podcasts I have those devoted to microbiology  


Theodore writes:

First time listening I know you guys are a lot smarter but what If the best way to get the vaccine to the liver was putting it to alcohol isn’t alcohol broken down by the hepatocytes.


-Theodore M. Nursing student thinking of becoming a parasitologist

Iosif writes:

Dear Talented Thrilling Tenacious Tantalizing Twip Team,

Once again on behalf of the entire Hofstra Northwell School of Medicine, I express our extreme gratitude for the textbooks. They are being given out right now and here are the first four recipients (I’m the second from the right). Thank you so much!


Iosif Davidov

Wink writes:

Professors of Parasitism (and not parasitic professors!),

I was reading a case similar to one of Daniel’s [CID 2016:63 (1 November) page 1212] and it made me think again about how wonderful evolution can be. Does S. stercoralis sense that its host is dying when going to the autoinfection cycle? And then, does it prepare the proper stage for the soil and finally engineer its host’s return to the soil? Do filariform larvae develop in the human body and will they be infectious in the soil near a buried body? The 

Wink Weinberg

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