Case guesses:

Alexander writes:

Dear TWiPsters,

The patient from Ghana has two different kinds of egg in her stool:

One of them quite large, with a characteristic lateral spine, must be the egg of Schistosoma mansoni, which is endemic in the region and can cause diarrhea and abdominal discomfort. She likely acquired these parasites by failing to towel off vigorously and immediately per the recommendation of Dr. Griffin after a bath in standing water. 

The other egg resembles those of Hymenolepsis nana, a cestode that can be found in most parts of the world and whose potential for pathogenesis is still unclear, as an infection is very commonly asymptomatic and often found concomitantly with other intestinal protozoa.

The question is, of course: which infection is responsible for the symptoms? Putting our quest for truth to the side, a simple solution might be proposed: Treatment with praziquantel 20mg/kg will be sufficient to treat both infections, and while we may be none the wiser, the patient will hopefully make a recovery. If this fails to yield results, another round of stool examination and peripheral consideration of the millions of other differentials of diarrhea might be in order. 

Thank you for this fascinating case, I had great fun as always. Best,

Alexander from Vienna, Austria

Trevor writes:

hi All

I really appreciate all you do to help educate us laymen about all things Microbe related.  Being retired now, I follow all your TWiV episodes and most of the other episodes when I can.  While I have an Arts degree with a science major, at most I can only be considered a science advocate as I enjoyed a career in business.  

My first time writing to you.    Relating to TWiP 204 and the case of the 20 yr old pregnant women with abdominal stress.

Regarding the larger oval which I suggest might be Schistosomiasis.   This disease is prevalent in Ghana, near fresh water, with symptoms as described.  The size of the eggs found in the feces was about right in the area of 150 microns and oval with single lateral projection.   

So, my uneducated guess is Schistosoma mansoni, which I have selected due to its presence in the intestine rather than the urinary tract.  Merck suggests treating with Praziquantel which is safe for pregnant women.  

Regarding the smaller oval present in the feces.  I first thought that the cause was Ascaris lumbricoides which had the added possible pathology of increasing pregnancy rates and given the women’s age and pregnant with her second child, it seemed like a possible fit.   The size of the eggs in the feces were a possible match to the smaller of the observed ovals.    

However, the presence of polar bodies suggest that it might be Trichuris trichiura or whipworm. It is not unusual that both are present in certain individuals in certain areas.  Treatment can be Mebendazole or Albendazole.     

Safety data might suggest that combined use of Praziquantel and Mebendazole may be tolerated.  Surgery might also be an option.

Here in Toronto it is -8 C, mostly cloudy.  Cool but very little wind, so not a bad day for a walk.  

Love all your shows.



Eyal writes:

Dear professors of the microverse,

Greetings from Sydney Australia where it hasn’t stopped raining since the last episode 🙁 we have been having once in a century weather events every year or so now, with severe bushfires and floods. But I have to say the latest floods are quite extraordinary with some places on the northern rivers being inundated by 17 meters of water (>40 feet).

Here is a picture of Lismore city centre before and during the last flood.

Enough of my rant.

To the case of the Ghanian woman with abdominal symptoms.

Again not being a medical professional or a biologist/parasitologist I only had Daniel’s microfilariae size and shape to go by.

The first one was quite distincts with its relatively large size and “lateral protrusion”. I think that would be Schistosoma Mansoni.

The second smaller one was a bit harder. At first I thought it might be Schistosoma Japonicum but the egg size of Japonicum was too large at 70-100 microns and also from images it looks like you don’t have a bilateral body inside.

On the other hand the description marches Strongyloides to a tee so I would go with that.

For treatment I’m a bit conflicted (and lost) as I don’t really know of any cross reaction between different medications.

On one hand, based on the WHO Praziquantel is the treatment of choice for all Schistosoma. For Strongyloides it seems that Ivermectin is the bees knees.

However, surprisingly I’ve stumbles on a pubmed article about a Ghanian 27 year old male who was diagnosed in 2015 Spain with both Schistosoma M. and Strongyloides but he was first treated with two doses per day of Bassado Antibiotic (tetracycline) for twenty days and then with a single dose of 3 mg of ivermectin that was repeated after 3 months.

Being completely uneducated in this I can’t make a call.

Am I correct to think that all guesses from last week were actually incorrect as the actual infection and symptoms of Onchocerciasis are in fact due to the Wolbachia bacteria?

Can’t wait for the next twip to drop (and for my book to arrive :)).


Patrick writes:

Dear TWiP,

Your call for more guesses several episodes back has borne much fruit. So as I write this, amidst a hovering freezing-mark and winter weather that refuses to yield its grip on Ontario, I’ll try to make this a short email.

The pregnant woman in TWiP 204, whom I thought may be suffering from two simultaneous infections, may in fact be suffering from a single parasitic infection.

Diagnosis (in part) is relatively easy, for what parasite enthusiast could fail to recognize the telling lateral spine of Schistosoma mansoni?

The major pathology in this case could be due to intestinal schistosomiasis, related to the presence of eggs (lodged in tissues and/or destroying tissues with proteases) in the small intestine. In my recent reading I gather this is not an uncommon presentation of Schistosomiasis in endemic regions.

The treatment would be Praziquantel, at 20 mg/kg twice per day. In this case treatment is recommended by WHO regardless of pregnancy stage. The CDC lists Praziqauntel as pregnancy category B, so I expect treatment with Praziqunatel proceeded.

All this said, I am surely missing something with the secondary smaller ovoid form mentioned by Dr. Griffin; thus I look forward to hearing what it is! 

My warmest April regards,


Michael writes:

Kia ora TWIPsters!

Hello from the antipodes in eNZed where Fall weather is heavily influenced by the southerly winds from the Tazman Sea and Southern Ocean.  It is slightly overcast today on the Tutukaka coast and 23 C (73 F), with showers forecast for this afternoon and evening. We “fell backwards” gaining an hour on Sunday and the annual tsunami siren test reminded those of us who forgot to change our clocks. This siren also reminds many Kiwis to claim daylight saving as a New Zealand invention, proposed by the entomologist  George Hudson, to allow for more after work hours to collect butterflies! As worthy a reason as any…

(If I can throw in a “Listener Pick”: , )

I was not planning to reply to Daniel’s “stump the chump” case but two things piqued my interest and forced me to dig in.  Daniel’s patient is a pregnant 20 yo from eastern Ghana with a history of frequent fresh water exposure in the Volta River Delta.  She is G2P1 in her second trimester of what appears to be a previously uncomplicated pregnancy now reporting bloody diarrhoea, abdominal pain and microscopic evidence of two ovoid forms seen in her stool sample.  

Ignoring a myriad of other pathogens that may play a role in this young women’s presentation, I wish to hop on “Ockham’s Razor” and cut to the chase:

1.  The 160 micron lateral spined ovoid unknown is the egg of Schistoma mansoni which is common in the Volta Delta where I believe the range of the Biomphalaria snail host was expanded after damming at Akosombo and Kpong such that it now overlaps with Schistosoma haematobium.  I know this structure well from my thesis work (with Dan Colley) embolizing eggs into mouse lungs to study T helper mRNA cytokine dynamics during granuloma formation.  Meanwhile, a young Barney Graham (of COVID19 mRNA vaccine fame) worked on the bench behind me using the same system to evaluate T helper responses to RSV vaccine candidates for his thesis. This, his seminal breakthrough on how viral surface protein structure can influence protective vs pathological host immune responses. (Vincent, can we please have him on TWIV?)

2. Initially I assumed the second ovoid unknown would be “ectopic” excretion of Schistosoma haematobium from a concomitant urogenital infection. But the 45 x 30 micron did not fit. Nor did this cryptic reference to a “polar body”.   To stop the bloodletting from the razor, I went back to listening to the banter between Daniel and Jackson, and even to watching everyones’ facial expression while Daniel described unknown #2!  Something was up between those two merry pranksters. I scoured the web and plied through old texts I have not touched in years and but for a size comparison of helminth eggs would I not have come across an uninteresting cestode ovum sizing at 45x 30 microns. Hello Hymenolepis nana, the dwarf tapeworm of world wide distribution and little medical consequence, and “polar thickenings from which extend filaments”.  Ha! I was hooked! 

And even better, I was in on their little inside joke. Fortunately for me, I was also rewarded by a heavy dose of geek and a deep dive into the wonders left to discover in this field as I listened to TWIP 99: You get your “Polar Bear” from your nana.  I will not spoil it here.

3.  To complete the workup, it would be prudent to confirm our patient’s other risks which may complicate her pregnancy.  Standard prenatal screening should include among other regional recommendations an HIV test and if positive CD4 count and viral load if possible.  Treatment as per local guidelines should be followed for any concerning investigations to include treatment for her helminthiasis.  I was aware Praziquantal had a category B recommendation from safety developed in prior animal studies, but I see now a number of case series and a recent placebo controlled RCT shows safety and efficacy in pregnant women to prevent complications. Verifying expulsion of the scolex would complete treatment I believe.

Can’t wait to find out if you stumped this chump! Hope not as I could really use a new Parasitology text updated to include the “Polar Body” bantered about by my most esteemed colleagues on last week’s TWIP!

Thanks for helping this peripatetic emergency doctor/Immunoparisitologist rekindle a love for the most mind-blowing field on the planet!

Kia kaha!


PS: Picture of me in a shirt I designed for the Biology of Parasitism Course at Woods Hole back in the day (1990): “UP PARASITE” featuring H. nana as a periscope!

Michael Howard MD PhD FACEP FACEM

Emergency Consultant, Whangarei, NZ

Anthony writes:

As luck would have it, a volume recently arrived at Jersey City Free Books.  The cover photo is of a well-groomed, adolescent boy in a suit.  The smile could be from Norman Rockwell, but the eyes are from HP Lovecraft.  In my mind I heard Dr. Griffin’s voice “a dark time in American History.”  The book is Manson by Guinn.

The ova with the lateral projection — knife like spike — are from Schistosoma mansoni.

Schistosoma  species are prevalent in Ghana since dam construction.

Professor Despommier has said “Once you’ve found something, keep looking!” and Doctor Griffin “Occam was not a physician.”  The crystal ball/ microscope slide has more to tell us.

From what I can make from the CDC chart

the smaller objects are the eggs of a tapeworm:

Hymenolepis nana



Neil writes:

Hello TWIP Quadrifecta

Greetings from Guelph, Ontario where it is 5 degrees C and rain-snowing (super gross). I’m a long time listener – started about four years ago when I joined the parasitology lab of John Barta at the Ontario Veterinary College (OVC) – on top of lecturing at OVC he also teaches a really excellent parasitology undergrad course that my friend Alex and I had the pleasure of taking. Thus, we submit a joint guess (I guess if we win we’ll set up a timeshare with the textbook?).

As for the pregnant 20 year old woman in Ghana presenting with abdominal pain and bloody diarrhea: We think that she is suffering from both schistosomiasis from s. mansoni infection, and trichuriasis from t. trichiura. Both seem to be present in this area of Ghana. Her symptoms seem to align well with trichuriasis, and the smaller ovoid body matches the egg morphology of t. trichiura. The schistosomiasis may be asymptomatic (for now), as we don’t think the symptoms align very well, but the size (or length?) of the ovoid form fits with the two schistosomes present in Ghana, mansoni and haematobium – however the lateral projection suggests mansoni because we believe haematobium’s projection is more distal. At least, according to the single picture we have decided is 100% representative of both species (we’re really good scientists). Both could occur from extended time spent in and around the river.

Love the show, thank you so much for what you do!


Kevin writes:

Dear Worm Doctors,

Regarding the pregnant Ghanian woman with two types of ovoid forms in her stool, my guess is that she is co-infected with Trichuris trichiura and Schistosoma mansoni. I would guess that the abdominal pain and bloody diarrhea is caused by a heavy whipworm infection, though schistosomiasis could contribute to both. I would go with albendazole for treatment of the whipworm, and praziquantel for treatment of the schistosome. I found sources indicating both are safe individually during pregnancy (PMID: 33914732; 29403101), and that a combination therapy of the two is safe (PMID: 19325515). 

Worm regards,

Kevin H

(still waiting to win a book)

Sara writes:

Dear TWiP experts, 

It’s evening in Philadelphia where it is -2 Celsius (28 F) with blue skies, intense sunlight with paroxysms of snow and gusts of freezing cold wind. My neighbor, an older gentleman, referred to this weather as “wake up weather.” I am indeed awake.

Dr. Griffin presents a 20-yr-old woman with abdominal pain and bloody diarrhea in the 2nd-trimester of pregnancy. She resides in eastern Ghana, in a wet environment, spending time in the river, where her skin has likely encountered mosquitos and snails (and cercaria released from them).  Viewing her stool under a microscope, Dr. Griffin found two distinct ovoid morphologies: (1) oval, 160 microns along a long axis with a single lateral spike, (2) 45-by-30-micron ovoid forms with two polar bodies within them. 

I believe the 160-micron eggs are Schistosoma mansoni. I can’t think of anything else that fits this description. I am guessing Dr. Griffin treated her with praziquantel (unsure of dose) x 2 and then checked her stools for cure. They probably also repleted her iron to address any iron deficiency anemia in pregnancy. Praziquantel should be reasonably safe in 2nd trimester pregnancy. I would not delay treatment. The blood in her stools seems to mean that the S. mansoni has begun to cause inflammation of her bowel wall leading to ulceration and anemia. S. mansoni climbs into the blood vessels draining the intestines. 

Somewhere in my piles of papers, I have a drawing of “Mansoni the Rhinoceros” which was my silly way of memorizing that Schistosoma mansoni eggs are the fattest and have a “rhino” horn that protrudes from the side of the eggs.  S. intercalactum I drew as an “intergalacticum” spaceship because it is narrow and really does look like a spaceship) and haematobium which I think of as haematuriabium and drew the egg looking like a bladder. Mekongi and japonicum are the smaller and rounder two and I think of “mini mekongi coin” to remember the roundness of the smallest of the Schistosoma group (which have relatively huge eggs as a cluster compared with other nematode eggs)

The 45-by-30-micron ovoid forms are harder to pin down. They seem a bit too small for a hookworm, too round to be a whipworm (but the two “polar bodies” sound like whipworm) and she isn’t complaining of perianal itch, so I won’t even consider pinworm. The term “Ovoid forms” is vague enough that it could include the largest-size ameba eggs–Cystiospora–but 35 microns is probably as big as the biggest amoeba eggs could be. So, I’m going to say it’s a whipworm, Trichuris. The polar bodies are hard to imagine as anything else. I would give her albendazole or mebendazole which are safe in the second trimester, though not in the first. I would also make sure she is taking multivitamins, and while she is in the clinic do a thick smear for malaria and treat if necessary. 

I hope she is doing well and taking in plenty of iron!! Two questions I had for the experts: Is there any particular reason why East African Trypanosoma is decreasing in prevalence? and (for Dr. Griffin) what counseling would you have us offer this patient to avoid reinfection? 

Thank you so much for always teaching me so much, and for the joy you bring!! I look forward to TWiP episodes so much!! 


Sara, MS4 (starting intern year in June!!) 

Byron writes:

Hello TWIP hosts,

A new case, how exciting! Really appreciate Dr. Griffin’s effort to bring cases to the podcast so we can all be armchair ID doctors without license or insurance or both… In this case, I think the lateral projection gave it away, sounds like  they were the eggs of schistosomes which according to PD 7, could be seen throughout Sub-Saharan Africa. 

No book yet but will keep trying. Thanks again for the wonderful podcast. Have a great rest of the day.


Kimona writes:

Greetings TWiP team!

I have been an ardent listener for some time now and frequently enjoy older episodes during my drives to work or hikes in the woods. Full disclosure – it began with TWiV, then I added some TWiM, and finally TWiP. At Daniel’s recent suggestion (thank you!) I plan to be in Panama with Floating Doctors for a few weeks in July – which has accelerated my quest for Parasitology knowledge even further! So, after much trepidation surrounding the public shaming that a ‘mis-diagnosis’ may bring me – I am submitting a response. 

The 20 y/o Ghanan female in her 2nd trimester presenting with abdominal pain and (bloody) diarrhea who lives near the Volta River Delta and stool microscopy findings of ovoid egg forms of ~160 microns with a single lateral projection – immediately makes me think of a Schistosoma mansoni infection – as one of the likely culprits of this woman’s ailments. Heavy intestinal infections can cause intermittent abdominal pain and also intestinal hemorrhage from damage to the submucosa – which could explain the blood detected in her stool.

Diagnosis of S. mansoni is by ID of eggs in the stool, with its very diagnostic lateral spine. A rectal snip can also be used in lighter or intermittent infections, to look for the presence of “flame” cells, and thus identify whether an infection is ‘active’ or not, and whether treatment is indicated. Blood tests looking for two schistosome glycoproteins, CCA and CAA, can also be used, as well as NAATs.

The second and much smaller egg of 45 x 30 microns, with its polar bodies, caused me more trepidation…..I turned to page 535 of my recently obtained (but unsigned!) copy of PD7 and found only Hymenolepis nana fitting this size. H. nana, or ‘dwarf’ tapeworm, is a Cestode and is listed as having worldwide distribution. Most infections with H. nana in adults are described as asymptomatic and self-limited whereas heavy infections can produce diarrhea. Headache, anorexia and abdominal pain are also listed as possible, but unclear if these symptoms may be due to coinfections with other parasites.

Diagnosis of H. nana is made by the identification of embryonated eggs in the stool (since it completes its entire life cycle within the human host). The polar bodies seen (which is what threw me off) – I am guessing is simply a byproduct of cell division of the fertilized, embryonated eggs?  

Treatment with Praziquantel is recommended in both S. mansoni and H. nana infections.

In S. mansoni, it will depend on whether her infection is acute or chronic. The fever and flu-like symptoms, or Katayama fever, of an acute infection was not mentioned – so hers is more likely chronic, and a single dose of Praziquantel could reduce or eradicate the worm burden and may even reverse some of the pathology of liver fibrosis (if present). However, it should only be initiated if the infection is ‘active’ – so, perhaps a rectal snip is further indicated?

In H. nana, a single dose of Praziquantel (5-10mg/kg), affecting both the cysticercoid in the villus tissue and the adult worm in the intestinal lumen, is recommended. Niclosamide can be used against the adult but it is not effective against the metacestode and must therefore be used for several days and possibly repeated until no further eggs are present on stool exam.

I did question the safety of Praziquantel in pregnancy, and found a 2016 correspondence in the Lancet reporting multiple cases of rather high-dose Praziquantel treatment in pregnant women without adverse effects on the fetus, leading me to believe this would be considered safe.

So, to summarize, I can imagine that this unfortunate young woman may have carried reasonably asymptomatic and undiagnosed infections of both H. nana and S. mansoni for quite some time, yet the added burden of pregnancy, the enlarging uterus and its space consumption within the abdominal cavity and pressure on her IVC, could be causing additional portal hypertension and congestion, perhaps exacerbating symptoms that were not previously prominent. She may also have immunocompromise (I do not recall Vincent’s usual questioning of her HIV status – one could imagine a co-infection w/ S. haematobium and its associated FGS and increased risk of HIV – despite marital status! – as possible) Her bloody diarrhea could exacerbate the mild anemia of pregnancy, largely due to volume expansion required to include the growing fetus. The good news (if any…) is that both these infections seem to respond to Praziquantel treatment – squashing “two parasites with one stone”!

I eagerly await listening to the final diagnoses.

Thanks to you ALL for keeping me engaged and excited about Parasitology!

Kimona, from rural southern Vermont (currently a balmy 51’ Fahrenheit)

P.s. much of the above came directly from PD-7!

Martha writes:

Dear TWiP team, 

Greetings from eastern Massachusetts. Hope you are all staying well. 

I’m responding to episode 204. This is the case of the young woman from the Volta River delta region in Ghana. We are told she is frequently in the river. She is in the second trimester of pregnancy when she presents with abdominal pain and bloody stool. We are also told that this is not her first pregnancy, but not the outcomes of prior pregnancies. (how many prior pregnancies, did she deliver at full term, was the infant’s size appropriate for dates, and are the children living? I digress.)

We are given the result of a stool examination. Findings are a 160 μm ovoid structure with a single lateral projection and 45 x30 μm ovoid structure with some polar structure.

A browse through images of parasite’s ova suggests that the larger structure is Schistosoma mansoni and the smaller is Hymenoleptis nana. 

Both could contribute to her symptoms. Although H.nana may be self-limited, because she is pregnant and therefore somewhat immune suppressed the infestation may persist.

Both can be treated with Praziquantel which is Category B in pregnancy. She is more likely to have a better pregnancy outcome without a parasitic infection. Is it possible for her to stay out of the river?

Best wishes to you all


Owain writes:

Dear TWIP,

I really enjoyed the last episode’s paper discussion and this case!

The larger eggs sound like Schistosoma mansoni, which in heavy infections can cause blood in the stool and abdominal pain. She has freshwater exposure too. The smaller eggs took some googling! But my guess for those is Hymenolepis nana, which might also be contributing to diarrhoea and gastric discomfort. Luckily, I think praziquantel is the treatment for both!

All the best,

Owain (just pronounced “Owen”)

Daniel writes:

Hello Team Twip,

It is 15 degrees with bright puffy clouds. Spring has sprung on the west coast, so now the garden is getting some attention. But now we must turn our attention to the pregnant woman in Ghana. Based on her symptoms and the ovoid forms found in stool it seems she has a dual infection with a schistosome and a nematode. Schistosome infections are acquired by wading in freshwater. These worms spend their adult lives in the mesenteric venules laying eggs in the endothelial wall which eventually penetrate their way into the intestinal lumen. I’m not exactly sure how the eggs accomplish this feat, but cysteine proteases assist them along the way. This process causes GI bleeding, diarrhea, and inflammation that leads to malabsorption syndrome (which would not be good for a developing baby). The lateral spine on the eggs means the identity of the schistosome is Schistosoma mansoni; unlike Schistosoma haematobium which have a single medial spine on their eggs. As for the other smaller ovoid forms they could either be eggs from Trichuris trichiura or hookworms. My notes are failing me again as I don’t have anything written down about polar bodies, I hope the rest of the team can fill in!


Daniel from Vancouver, Canada

Andrew writes:

Kia ora from Pongaroa,

Weather is autumnal with a long lasting La Niña supplying warm and humid weather.

It is so good to be able to use my physical copy of PD7 to answer a question. Thank you TWiP team, I so much prefer to read off paper than a screen. 

I could not find a table of parasitic ova and morphology online but the suspicion that the young pregnant woman was infected with Schistosoma mansoni was firmed up by looking at the pictures in the book. She has either that or is hosting miniature sharks. The second type of eggs with polar bodies I cannot identify with such confidence but I suspect Ascaris lumbricoides. 

So if my guess is accurate then, after confirmatory tests, the young lady should be treated with Praziquantel as that is safe for pregnant and breast-feeding women according to and Nitazoxanide if A. lumbricoides is the second infection. 

A tangential question – is a reliable source of information? Not that I am ever going to recommend anyone take anything stronger than an aspirin. 



Jon writes:

Hello Twipperati and wishes for good weather to be Springing forth for each of you.

I have previously submitted some guesses but unfortunately either submitted just a hair too late, been filtered out and mistaken for spam, or, in the case of TWIP 199, I’ve not quite known how to submit an answer with the tact of a Clinician.

I can only hope that I am not submitting a guess that is too far delayed again for this March 28th episode release.

In the case of the 20 year old Ghanan woman who is with child, it appears that there is evidence of both parasites that may be the source of complaint as well as possible sourcing for future complaint. 

As the woman admits to often being in the rivers of the delta, and the geography and description matches the specifications of exposure to Schistosoma Mansoni via penetration by waterborne cercariae, it is likely that the ovoid forms found in the stool that measure 160 microns, as well as having a single lateral projection, are in fact the eggs of the adult female trematodes being shed from their residence in the patient’s mesenteric venules. 

That said, it is not necessarily the case that the S. Mansoni would be related to the patient’s complaint of abdominal pain and bloody diarrhea, as the patient is an adult and is not presenting typical acute response symptoms. It seems possible that the woman is a lifelong resident with repeat exposures to the parasite and may be developing toward indications of chronic schistosomiasis and associated fibrotic complications as well as hepatosplenomegaly.

Praziquantel treatment to remedy the infection may be administered immediately, as studies support an unlikely negative impact upon fetal development and birth weight, but label indications appear to assert use during pregnancy only if required.

The secondary entity found in the stool, however, leads me to conclude that the S. Mansoni may be the cause of the complaint. As, while I am uncertain that the the ovoid entities with “polar bodies” and measuring 35×40 microns fully fit the description, I am led by geography and the best description for what I take to be said polar bodies as indication that these entities are fertilized, non-embryonated eggs of Trichuris trichiura living and shedding in the large intestine of the patient. 

As treatment for T. Trichiura would be either albendazole or mebendazole, which have animal-model teratogenicity indications, and the mother is in her second trimester, treatment would only be administered if deemed necessary, which does not seem apparent due to the patient’s infection appearing to be correlated to the S. Mansoni infestation.

I can only hope that I indeed staggered my way through the logic and elimination for this case and, as always, thank you all for such a great podcast that has done a fantastic job in igniting an interest in parasitism in myself and so many others.

Jon A

Danika writes:

Hello Twip Team!

I very much enjoyed the discussion of the pronunciation of my name. Dickson is right, I do pronounce it Dan-IH-kah, not Dah-NEE-kah. HOWEVER, I have known several other “danicas” who pronounce it Dah-NEE-kah. So both are correct and it seems to just be a matter of preference! Regardless, I enjoy hearing Christina’s pronunciation of EVERYTHING!

Anyway, writing in for the Office of Infectious Diseases Assessment Unit parasitism club at a state health department! 

The most likely culprit of infection for the pregnant Ghanian woman is schistosomiasis, also known as Bilharzia, also known as snail fever. Bilharzia gets its name from Theodore Bilharz who discovered the disease and life cycle, though we agree we would not prefer to have this disease named after us.

Infection is acquired when people contact contaminated water and the fork-shaped larval worms penetrate the skin (IIIIICK!) and become adult worms. Infection can be acute or chronic, intestinal or urinary. Although most people do not develop symptoms of acute schistosomiasis, when symptomatic, symptoms include abdominal pain, bloody diarrhea, cough, malaise, headache, rash, and body aches. Individuals who have had prior infections are most likely to develop high temperatures known as Katayama fever. Although symptoms resolve after a few weeks, mortality rates can be as high as 25% during this acute phase. In chronic Schisto, symptoms can present months or years later and may include formation of granulomas. 

The gold standard for diagnosis is eggs in the stool, though eggs are only intermittently passed and require adult worms to be producing eggs, so serological tests can be used to diagnose less advanced infections.

Given that this woman is pregnant, treatment should begin immediately as studies do suggest schisto infection during pregnancy can lead to low birth weight, pre-term delivery, and an increased infant mortality rate. Fortunately, standard treatment with praziquantel appears to be safe during pregnancy.

Mass drug Administration of PZQ has been successful in Egypt where prevalence of S. haematobium in Middle and Upper Egypt fell from an average 29.3 % in 1977 to less than 3 % by the end of the 1990s followed by an even lower rate for S. mansoni (1.5% average prevalence). The assumption is that mass drug administration would lead to reduction in excretion of schistosome eggs, contamination of the environment, and infection of the snail population, which in turn would lead to less source of infection for humans. However, for those who do not comply or are not covered by mass drug administration, such as school-aged children who are not enrolled in school, they may still spread the infection.  Interestingly, one of our team members is from Egypt, and he said that the flip side of the Mass Drug Administration project was that it utilized syringes (this was before disposable syringes) and was the unfortunate main cause for Hepatitis C spread. Fortunately, Hep C is now controlled by the modern treatment options, and PZQ can be administered orally.   

Most of our team works in sexually transmitted infections so we took particular note of the fact that urogenital infection in women can increase the risk of HIV. 

Final note, (for Daniel) rigorous towel drying after contact with potentially contaminated water is advised, but may not be sufficient to prevent infection.

Thanks for the fun case!

Assessment Unit Parasitism Club

Dear TWIP professors

Greetings from Parasitology Club at University of Central Lancashire in the beautiful northwest of England.

We would like to add our considered opinion for the case of a 20-year-old pregnant woman who resides near Volta River in eastern Ghana in sub-Saharan Africa. The woman was in her second trimester and complained about abdominal pain, often with bloody diarrhea. 

The Volta River basin is a fresh-water body used by locals for daily chores. 

The most probable cause of her condition is schistosomiasis. Schistosoma mansoni is a blood trematode (fluke) producing elongated ova 155-160 microns in length which has a small lateral spine as shown in Figure 1 (Despommier et al., 2019).

When excreted through the faeces of an infected human into a freshwater body, the eggs hatch and release miracidia which uses freshwater snails (of genera Biomphalaria) as their intermediary hosts (CDC, 2019a). Free swimming cercaria develop and are released from snails into the water body. Cercariae can easily penetrate through human or animal skin and transform into schistosomulae which migrate via venous circulation and reaches the portal vein system to mature into male and female adult worms. After copulation, the female lays eggs in the mesenteric venules of bowel or intestine which are passed into stools. The worms are relatively harmless to human hosts however, eggs cause severe disease and symptoms in the intestinal tract (, 2020). Granulomas form around the egg and early symptoms include rash or itchy skin. After several years of infection, the adult worms can damage the liver, intestines, lungs, and bladder.

According to a study conducted by Derso et al (2016), pregnant woman in their second trimester have increased chances of getting intestinal parasitic infection due to several factors. These infections can be treated with praziquantel since it is most effective against the adult worm (Brunette and Nemhauser, 2020)

Thank you for another interesting case.

Prathamm Surana

On behalf of the Parasitology Club, University of Central Lancashire.

Reference list

Brunette, G.W. and Nemhauser, J.B. (2020). CDC yellow book 2020 : health information for international travel. Oxford: Oxford University Press.

CDC (2019a). CDC – Schistosomiasis – Biology. [online] CDC. Available at: [Accessed 9 Apr. 2022].

CDC. (2019b). CDC – DPDx – Diagnostic Procedures – Stool Specimens. [online] Available at: [Accessed 9 Apr. 2022].

Derso, A., Nibret, E. and Munshea, A. (2016). Prevalence of intestinal parasitic infections and associated risk factors among pregnant women attending antenatal care center at Felege Hiwot Referral Hospital, northwest Ethiopia. BMC Infectious Diseases, 16(1).

Despommier, D.D., Griffin, D.O., Gwadz, R.W., Hotez, P.J., Knirsch, C.A. and Katz, M. (2019). Parasitic diseases. New York: Parasites Without Borders. (2020). CDC – Schistosomiasis – FAQs. [online] Available at: [Accessed 9 Apr. 2022].