Amber writes:

Good afternoon, TWiP team, it is a frosty -22 degrees Celsius with a wind chill of -34 here in Halifax, Nova Scotia, Canada. Luckily, it’s going back up to +2 Celsius tomorrow.  I am a long time listener of TWiP (and all other microbe tv podcasts), but this is my first time emailing you.  I have an MSc. in plant and soil biology, but I absolutely adored the parasitology course I took in my undergrad, so TWiP is a treat for me.  

I searched Google for parasites in Corsica causing hematuria and was rewarded with an article in Emerging Infectious Diseases entitled “Developing Endemicity of Schistosomiasis, Corsica, France.”  It was on the PubMed Central site and it appears to describe Dr. Griffin’s exact case study, a 49 year old German male with hematuria after a trip to Corsica.  He appears to have been infected with a hybrid parasite, Schistosoma haematobium x Schistosoma bovis, which was apparently responsible for a schistosomiasis outbreak in Corsica in 2013.  It goes on to say that although no previous cases from the Solenzara River have been documented, Bulinus truncatus snails and their DNA have been found there through environmental sampling (this is the intermediate host species for these schistosomes) and their density around the patient’s primary bathing site was high.

Based on this article, I am going with Schistosoma spp. infection as the diagnosis.  According to the CDC, treatment for urinary and intestinal schistosomiasis is 1 to 2 days of Praziquantel.

Thanks for everything you do at, you all helped me get through the pandemic and stay sane. I am presently enjoying Dr. Racaniello’s Columbia Virology course (for the 3rd time, there’s something new every year) and I hope I can win a copy of Parasitic Diseases, 7th edition!

All the best in 2023,


Josef writes:

Dear TWiP Tetrad,

Long-time listener, first-time emailer. I started listening to TWiP while I was an undergrad at Penn State studying molecular biology. Six years later, I am in the 4th of (hopefully!) 8 years in the MD/PhD program at the Medical University of South Carolina in Charleston, SC. While my current PhD research lies in the field of liver biology and metabolism, I love listening to the TWiX podcasts to get my dose of infectious disease content while waiting for Western blots to develop.

I believe the 49-year-old German man with gross hematuria and a history of freshwater exposure during travel to Corsica is suffering from schistosomiasis caused by Schistosoma haematobium.

An outbreak of schistosomiasis occurred in Corsica in 2013 (described here in a 2016 article) and was traced to infection foci in the Cavu River. The patient in our case study describes swimming practically everywhere except the Cavu, but I think it’s conceivable that following the initial outbreak the parasites have spread to other rivers via endemic freshwater snails and river-hopping human hosts. The 2013 study demonstrated that, at least in laboratory conditions, snails indigenous to Corsican rivers could become infected with schistosomes which supports this theory. Interestingly, sequence analysis of Schistosoma specimens from the outbreak led the researchers to conclude that the parasites had likely traveled to Corsica from West Africa, specifically Senegal. It’s amazing what molecular biology can do! 

The diagnosis could be confirmed by identifying the presence of eggs with a hallmark terminal spine in the urine. Alternatively, serologic testing for antibodies against the adult worms could be employed. Treatment would consist of a two doses of praziquantel given over the course of one day. While one day of treatment is often enough to cure the infection, some patients may require a second treatment 2-4 weeks after the initial dose to increase the treatment effectiveness. 

Thank you for all that you do!


– – – – – – – – – – – – – – – – 

Josef Blaszkiewicz

MD/PhD Candidate

Medical University of South Carolina

Charleston, SC

Eyal writes:

Dear sages of microscopic Eukaryotes,

G’Day from Sydney Australia where the Summer is glorious and the Cicadas are so loud that you can’t hear yourself think 🙂

As to the 49 y.o. German male with significant gross hematuria. First, I’m sure this would have been 1000 times harder if this wasn’t a parasitic-focused show. 

I have approached this first by looking at parasites in France/Corsica which may cause hematuria.

A quick search returned the following list: Schistosoma mansoni, Echinococcus granulosus, Toxoplasma gondii, and Entamoeba histolytica.

Further examination helped me filter out the unlikely culprits.

Schistosoma mansoni is only known in mainland France but not on the island of Corsica

Toxoplasma gondii normally, as far as I know, infects the brain, skeletal muscles and eyes. it would also result in flu-like symptoms which the gentleman has not reported.

Entamoeba histolytica looked possible at first glance. it’s an amoeba so could be easily transferred in the unsanitary conditions of a campsite. However, it would have infected mainly the gut and the gentleman has not reported any gut symptoms.

Echinococcus granulosus (I really hope it was not Alveolar Echinococcosis) however looks likely.

It is caused by the larva stage of the tapeworm

the host is the dog with the infection occurring when the dog eats an intermediary host’s internal organs

This could easily contaminate the river

From the CDC website: Echinococcus granulosus often remains asymptomatic until hydatid cysts containing the larval parasites grow large enough to cause discomfort, pain, nausea, and vomiting. The cysts grow over the course of several years before reaching maturity and the rate at which symptoms appear typically depends on the location of the cyst. The cysts are mainly found in the liver and lungs but can also appear in the spleen, kidneys, heart, bone, and central nervous system, including the brain and eyes.

I would assume a cyst in the kidney has ruptured resulting in hematuria.

Recommended treatment is surgery to remove the cysts and Albendazole 400 mg orally twice a day for 1-6 months to kill any other parasites in the body or any eggs that might spill from the removed cysts.

Question: would it be required to scan the lungs, heart, and CNS for other cysts?



Unfortunately, my guess was not read out last month but I still want to share with you an amazing sunset we experienced while camping by Myall Lake (No Shistosomiasys in sight) over Xmas.

Håkon writes:


First time listener, and second year vet student at UGA on the wildlife disease track with hope to become a board certified parasitologist following my graduation. Having recently gone down a rabbit hole of reading about Schistosoma haematobium and mouse models attempting to replicate infection in humans (I was actually supposed to be compiling references for a paper on Clinostomum spp.); when I heard “urinary tract” and “mediterranean region” (Corsica) on your podcast about parasites, my mind went to this particular trematode. Given this guess it would be prudent to examine the urine sediment for ova to confirm as well as run a PCR for confirmation. Treatment would be praziquantel (assuming it’s the same for human medicine). From there, I did a little research to confirm this theory and I think I may have found the exact case you referenced on NCBI website-

 Was not aware that hybridization between the human schistosomiasis and the cattle varieties (S. bovis) hybridized as commonly as this paper suggests. Very cool stuff. Hopefully I turned this in on time for the drawing on the book, and I’m looking forward to meeting some of the TWIP cast this summer at the ASV conference!


Bren writes:

Aloha  TWIPers,  

It is 76 degrees Fahrenheit and balmy here on the beautiful island of Oahu.  I have just stumbled across this podcast and have decided to flex my Google skills.  My suspected diagnosis would be a parasitic infection by:

Schistosoma haematobium

as its geographical distribution includes Corsica France according to the World Health Organization.  

To confirm this diagnosis I would attempt to detect parasitic eggs in a urine sample and if confirmed treat with Praziquantel,

Then I would go back to balancing my spreadsheets, as I am not a medical professional!


Marcus writes:
Hi all, for once I’m not too late! I have previously gone on far too long tangents with these case guesses, but will try and likely fail to keep it short this time.

I have been listening to TWIP long enough to know that swimming in Lake Victoria = Schistosomiasis. Furthermore, that, in addition to denial being a river in Egypt; the the Nile carries S. haematobium. Now, if you were swimming in fresh water in those areas, and a while later developed macrohematuria – the answer would be clear – S. haematobium; and possibly squamous cell carcinoma secondary to the infection (unlike other bladder cancers, which are usually urothelial adenocarcinomas).

However, this guy was in Corsica – and we don’t do human Schistosomes (we do have avian schistosomes causing swimmers itch) in Europe, do we? Oh, yes we do! Multiple cases of local transmission and actual outbreaks of schistosomiasis have been reported in Corsica. Specifically in Cavu river, which our patient claims not to have entered; but likely also in Solenzara and Restonica rivers, where he did swim.

So depending on the cystoscopy and biopsy, treat for schistosomiasis with praziquantel, and possibly a bladder SCC with cystectomy with lymph node dissection if low grade (after radiographic examination with CT TAP).

Hope you are all well, thanks for helping me through the CTropMed;


Trondheim, Norway.

Joshua writes:

Dear Doctors,

I will simply guess schistosomiasis again, as a quick google revealed this disease has recently become endemic to Corsica.

Yours sincerely,


Derrick writes:

Hello TWiP! My name is Derrick and as a Floridian undergrad I might stand out from the usually more qualified submitters. Still, my introduction to parasitology professor sparked my interest on this subject, and your podcast has only furthered it! Speaking of my Professor, On the off chance he listens to this podcast shout out to Professor Paul Sharp! I hope a correct diagnosis can translate to an extra credit point or two, at the very least remember my name when you’re looking for new TAs.

Now, on to the case…

The first symptom; gross hematuria tells me that this particular parasite likely targets the human kidney or bladder. I figure the kidney is a more likely culprit as a parasite searching for high concentrations of water and useful biological material like sodium would likely end up there. 

Alternatively bloody urine could simply be a signal that the parasite is targeting another organ and then excretes its eggs through the urine of its host.

Considering the patient has been swimming around Southeastern France and that was the likely cause of infection I figured the pathogen most likely belongs to the genus Schistosoma. Freshwater rivers likely have freshwater snails, and freshwater snails likely have Shistosoma ready to bury themselves into human skin.

Googling ‘Shistoma bloody urine’ tells me that the most likely Shistosoma that causes bloody urine and a lack of other symptoms is S.haematobium otherwise known as the urinary blood fluke. This nasty little guy targets the venous plexus (a concentration of veins) around the urinary bladder and released eggs travel to the wall of the urine bladder, according to Wikipedia. My first qualm with this diagnosis was that this particular patient has visited rivers, which in my head are usually fast-moving and not snail friendly. Searching pictures of these locations dashed these worries as there seems to be locations with stagnant snail-friendly water.

This all seems good but to double check, I googled S.haematobium infections in France. Guess what popped up? According PubMed, and the European Center for Disease control cases of S.haematobium are not unheard of in, drumroll please, Corsica! In fact from June 16th 2014 to June 4th 2015 this trematode caused a ban on swimming in the rivers in Corsica! While the ECDC reports that Bulinas snails in multiple sites all tested negative for S.haemarobium in the summer of 2014, I wouldn’t be surprised if the pathogen has reared it’s head once again in Corsica at the time of our unfortunate patient’s trip.

Urological examination will likely result in observable eggs, and Serology examinations (ex.ELISA) will also likely point to whether S.haematobium is truly the culprit. Treatment may include an anti-inflammatory to alleviate symptoms and likely praziquantel. 

Enough fun parasitology, time to get back to Organic chemistry. 


Holtfreter MC, Moné H, Müller-Stöver I, Mouahid G, Richter J. Schistosoma haematobium infections acquired in Corsica, France, August 2013. Euro Surveill. 2014 Jun 5;19(22):20821. doi: 10.2807/1560-7917.es2014.19.22.20821. PMID: 24925456.

29-06-2015-RRA-Schistosoma haematobium-France, Germany, Belgium, Canada (


Jason writes:

Greetings TWiP Hosts!

It is a brisk 6 degrees Celsius in Seattle as I write this.

 For the TWiP 213 case of the German man with hematuria and no other symptoms, my first inclination was to suspect infection of the perivesical venous plexus of the bladder with Schistosoma haematobium. Reflecting on what I know about schistosomiasis, however, I thought I must be mistaken, because our patient had traveled only within Europe, and my recollection of S. haematobium endemic range heat maps confines this infectious trematode to its human and snail hosts residing in Africa, the Arabian Peninsula, and the Tigris-Euphrates river valleys.

Vexed, I turned to the 9th edition of Hunter’s Tropical Medicine and found a differential diagnosis table for patients presenting with hematuria. While there are many infectious and non-infectious etiologies contained within the table, the only parasitic malady listed here is S. haematobium.

Next, I searched “CDC Corsica” on the internet and the first page that appeared was a traveler’s warning on schistosomiasis, a warning which has apparently now been removed from the CDC website.

Other online searches for hematuria in parasitic diseases offered cystic echinococcosis as a possibility but I think that hydatid disease in this case is a bit of a stretch, especially when the case report heavily emphasized the “swimming in rivers” part of the history, and made no mention of contact with canids. Hematuria in malaria was also listed, but it seems improbable that a patient with malaria would not have other signs and symptoms to accompany the hematuria.

Therefore – while S. haematobium is not a typically endemic disease of European islands – I am pairing the evidence garnered between Hunter’s Tropical Medicine and the CDC and making a presumptive diagnosis of S. haematobium infection.

Worm regards,


Ben writes:

The patient likely has “…a mixture of Schistosoma haematobium, S. bovis and S. haematobium–S. bovis hybrids.” This was reported by the BMC blog “BugBitten” 

I Googled “corsica parasites,” and found this near the top of the results. The year, method of tracking with phone pictures, and the nationality of those infected matched. If I did not have this article to provide an incredibly detailed answer, I would look for evidence of Schistosoma with an antigen test. If present, then further phylogenetic work of the kind the ECDC conducted would be the next step. I guess patient treatment would be similar to that of the other Schistosoma species.

Then snail and bovid control. 

Thank you,

-Ben in D.C.

(prior book recipient)

Rawan writes:

Salam from Kuwait!

My name is Rawan and this is my first time writing in. I stumbled upon the TWiV podcast in 2020 (of course!), and was delighted to find many other podcasts where you guys discuss the fascinating subject of Microbiology.

I am currently a 3rd year Clinical Microbiology Resident at Kuwait Institute of Medical Specialization, after taking an 8 year hiatus to stay home with my 2 children while my husband completed his residency in the U.S.

I had originally planned a career in public health, but I fell in love with clinical microbiology when I entered the lab for the first time in 2019. 

The pandemic delayed my plans for a tiny bit but now I am half way through the residency and could not be happier!

Before I guess the cause of the German gentleman’s symptoms, I would like to comment on a subject that was discussed a couple of podcasts back: taenia solium:

Kuwait is an Islamic country where pork is prohibited, therefore nobody in the country is able to consume it, and yet, we do have cases of cysticercosis. This baffled me when I first knew about it, until I learned that the source was from cooks who were originally from countries where pork is a common part of the diet, who then come to work in Kuwait.

Now moving on to the case, hematuria of parasitic origin will always raise the flag of Schistosoma haematobium in my mind, a parasitic infection caused by swimming in freshwater lakes. 

A case report from 2014 reported the autochthonous infection of a young boy by Schistosoma haematobium after swimming in Corsica, France.

The distribution of this parasite naturally depends on the ecology of its intermediate host, the Bulinus snail.

Cercariae released from infected snails into lakes, will penetrate the human skin (causing a rash called the swimmer’s itch roughly 24 hours later), and migrate within their new host. The adult worms can be found living in the venous plexus of the urinary bladder, and weeks later, if large amounts are eggs are produced and shed, chronic granulomatous inflammation and fibrosis of the urinary tract occurs, which is the cause of “terminal” haematuria.

Diagnosis is by the detection of eggs in a terminal urine specimen collected between 12 and 2 pm.

Treatment is 40mg/kg of Praziquantel.

This was fun! Thanks so much for everything you do,

Rawan Dashti


Kuwait 🇰🇼 

Maria writes:

Hello twippers!

My name is María, I’m an infectious diseases clinician working at a small community hospital near Buenos Aires, in Argentina. I started following the podcast a couple of months ago and I’m slowly working through the early episodes as well as listening to the new ones as they come out. I must say one of the main reasons I got hooked on twip is that Dr. Despommier reminds me of one of my old teachers back in residency, Dr. Olindo Martino, both in erudition and in narrative prowess.

Into the case now. The one parasitic infection that comes to mind when faced with gross hematuria is urogenital schistosomiasis, caused by Schistosoma haematobium. Differential diagnosis that come to mind are either non infectious (bladder tumors, kidney stones, IgA Nephritis, Schonlein Henoch purpura) or non parasitic (bacterial UTIs including urinary tuberculosis). So when I heard about his travel history I was stunned for a moment. Reading up on the geographic distribution of S. haematobium I learned about the outbreak of urogenital schistosomiasis in Corsica 2013, with its epicenter in the Cavu River.  The parasite involved in this outbreak is a hybrid of S.hematobium and S.bovis and has been endemic in the region ever since. Most cases reported exposure to the Cavu River water, but more recently cases that had been exposed to nearby rivers such as the Solenzara River, where our German was. There is another report of a small outbreak of urogenital schistosomiasis in Almería, Spain; and the intermediate host, the Bulinus snail has been identified in Portugal, Spain, southern France, Greece and Italy.

So urogenital schistosomiasis caused by S.haematobium x S.bovis acquired in Corsica is my diagnosis, and my guess is the pathology of the bladder biopsy identfied granulomas surrounding the eggs. The diagnosis could have been made by microscopic examination of the urine, and treatment of choice is praziquantel.

Thank you for sharing this most interesting case, I can’t wait to listen to the resolution.



Michelle and Alexander from the First Vienna Parasitology Passion Club write:

Dear Schistosomu-Ladies and Schistosomu-Gentlemen,

As indicated by our unchanged greeting, we believe that what you have presented here is yet another case of schistosomiasis, this time most likely urogenital schistosomiasis caused by an infection with S. haematobium. We base this assumption not only on the typical presentation and history, but also on the fact that we recognise the case, which was published in 2021.

The condition known as urogenital schistosomiasis is brought on by S. haematobium worms that lay eggs and live in the veins that drain the bladder, uterus, and cervix. The parasite’s infectious larval stage, cercariae, which emerges from freshwater snails, infects patients by directly penetrating their skin. The worms travel to the venous plexus of the bladder, where they settle and lay thousands of eggs per day. Some of the eggs are eliminated through urination, the rest remain trapped in the capillary system of the pelvic end organs, where they can cause inflammation, fibrosis, granulomata, and eventually fibrotic nodules better known as sandy patches – all possible findings of cystoscopy and biopsy. Urinary schistosomiasis can also lead to more severe complications such as renal failure and bladder cancer. In fact, S. haematobium is considered a carcinogenic biological agent for bladder cancer and often affects patients at a young age. Treatment options depend on the severity of the disease and include treatment with Praziquantel or combinations of intravesical chemotherapy, immunotherapy, radio-chemotherapy and surgery in the case of bladder cancer. 

While staying in Corsica myself last year, I therefore took care not to expose myself to this infection. Granted, visiting in March, when the ambient temperature is around 15°C, makes it easier to resist the temptation of jumping into a river. That said, I wholeheartedly recommend visiting the turtle sanctuary “A cuppulata” near Ajaccio, which the patient also endorsed.

 Thank you for this great case. All the best, 

 Michelle and Alexander from the First Vienna Parasitology Passion Club

Mikayil writes:

Dear TWiP team, 

My name is Mikayil (ma-kyle) and I recently started listening to your podcast, and am excited for it to be added to my podcast repertoire. It’s a pretty nice day here in Knoxville, TN. I’m currently a sophomore undergraduate student at the University of Tennessee Knoxville, studying animal science as a part of the school’s pre-vet track. I also happen to work in the diagnostic parasitology lab at the university vet school. That said, my parasite knowledge is still fairly basic (and mostly animal based), but I felt it was worth at least trying to make a guess on the show.

Thinking about this case I started with what I know, consulting my borrowed copy of Georgis’ 11th edition from the lab in which I work. There are two main parasites that affect the urogenital system in dogs and cats (what I’m most familiar with) First is Pearsonema Plica, which can be found in the epithelium of the bladder. If infection is severe enough it can cause hematuria, but I wasn’t able to find much in the way of evidence that humans can be infected. I was therefore pretty quick to set that aside for now. The second parasite is Dioctophyme Renale, which will spend time growing in the kidneys and pass eggs through the urine. This parasite can infect humans, if they were to ingest a paratenic host (paratenic hosts for D. Renale include a number of freshwater fish and amphibians), but infection is rare. Epidemiologically speaking though, I was not able to find any evidence of Dyoctophymiasis in Central Europe. Also worth noting that Dyoctophymiasis is characterized with Eosinophilia which was not described in the patient, so I went ahead and set aside this diagnosis as well. 

After ruling out C. Plica and D. Renale I found myself out of my main area of knowledge, so I consulted the faculty lead of the lab I work in (Dr. John Schaefer) who mentioned that some schistosomes can cause hematuria, though he let me know I’d have to do my own digging to find out more about specific species. Which led me to Schistosoma haemetobium, which conveniently has been observed in Corsica France according the WHO. So my final answer is Schistosomiasis, by S. Haematobium which the patient must have contracted on one of his trips to France. Urogenital schistosomiasis is characterized by hematuria, but I hope the German fellow has not developed a severe case, because it can lead to kidney damage and fibrosis of the bladder and ureter, even bladder cancer. A standard filtration test of the urine would go to prove/disprove this theory. We may also be able to use some kind of antigen test (like the one we learned about in this past episode) in order to confirm schistosomiasis. If it is indeed schistosomiasis a course praziquantel should clear it up. 

I hope I did okay with my first (of hopefully many) entries on your show. Thank you again for making such an intriguing and educational podcast. Can’t wait to hear more! 

Best regards, Mikayil.

Martha writes:

Dear TWiPsters

I am behind in my TWiX listening. I just listened to Episode 213 and realized that the deadline for entries is in two days. So I am unable to do my usual mulling and ruminating. 

This is the case of a 49 yo German man who while vacationing in Corsica swam in several rivers. He avoided the Cavu river since it was known to harbor parasites. Hematuria prompted him to see a urologist who then referred him to ID. (Am I falling prey to some cultural stereotypes if I assume he was a smoker and wears a snug speedo when swimming?)

Prior to cystoscopic biopsy results, the diagnosis at the top of the differential was likely carcinoma of the bladder given the age and assuming a smoking history.

The urologist made the referral after the biopsy result and not because the cystoscope could not be passed due to an obstruction. So we rule out the Candiru, that spiny Amazonian catfish rumored to swim into human orifices. Our swimmer was not in the Amazon and the snug speedo should have offered protection from Candiru encroachment.

This takes us back to Corsica and parasites in the rivers. Although the Cavu was the first river to be identified as having Schistosomes it is likely that they have spread to the other rivers since the snail needed for the life cycle (Bulinus truncatus) is present in other Corsican rivers. More likely that the parasite was introduced by infected humans or other animal hosts, than that the snails made the trek from the Cavu to the Solenzara.

So my guess is that the man has Schistosomiasis due to S.hematobium, and that he will be treated with Praziquantal.

Best wishes to all

in haste


Byron writes:

Hello TWIP hosts,

Here we go, another case study, I really enjoy the monthly case study and please keep it coming! I  drive my kids every Sunday to his violin practice (about 1 hour each way) and it has been my time to consume all the Microbe.TV podcasts. It is been great!

49 yr German male with hematuria. No travel history outside Europe with two trips to France, including Corsica. Exam was unremarkable, normal blood count and no eosinophilia. The complaint triggered cystoscopy and biopsies and the findings triggered referrals to the Tropical Medicine department at LMU Hospital Munich.

Thought process. It appears it is the cystoscopy and biopsies that sealed the diagnosis. So diving into the procedure, cystoscopy is endoscopy of the urinary bladder via the urethra. So the biopsy was done from either the urethra or bladder. Next step, google search parasite causing hematuria. Top results from WHO website, “The classic sign of Urogenital schistosomiasis is hematuria.” mmm… could it be the schistosomes? Onto the PD version 7 textbook. It has been suggested that cases of hematuria might go back as far as ancient Egypt caused by S.haematobium. The textbook also mentions chronic schistosomiasis can develop hematuria as well as symptoms that mimic urinary tract infections, among other clinic presentations. So far so good, everything is pointing to S. heamatobium as the culprit. But one more thing, epidemiology. the patient had stayed in Europe the whole time, does that match up with epidemiology data? Further reading in PD7 showed S. haematobium is prevalent in most parts of the Middle East, however an outbreak of S. heamatobium was also reported in Corsica, France that was most likely initiated by an infected individual from Africa who had migrated there. The small print in the text refers to papers published in 2011 and 2014, and the patient mentioned travel history to Corsica 7 years ago. Not sure when is this case, but 2014 plus 7 years would be circa 2021, seems reasonable. Here we go, I think I am going with Schistosoma haematobium as the diagnosis for this case. Hoping for a book in near future, and thank you for everything you do educating the public. 


Christopher writes:<=winner

Hello twip malacologists, 

Could it be possible that the patient presenting with hematuria is one of the people infected with the Schistosoma Hematobium-Bovis Hybrid that occurred in Corsica, France? This hybrid is capable of causing hematuria as the eggs make their way from the venous plexus of the bladder where the schistosome adults live into the lumen of the bladder. This hybrid also seems better than its parents in infecting each respective snail host, suggesting that it has the potential to outcompete its ancestors out of the water. 

A quick short course of Praziquantel should do the trick. 


Christopher Hernandez

David Geffen School of Medicine, MSII 

MPH 2020

Infectious Diseases and Vaccinology 

University of California, Berkeley

Gina writes:

I m sorry but my best guess is schistosomiasis again from what meager research skills I have left.

Tell Dickson how much we liked Office Hours with Dickson and Vincent! 👍👍

Gina. 😊👍🙋🏻‍♀️

Kimona writes:

Dear TWiP Team,

“With age comes wisdom……but sometimes age comes alone.” I clearly struck out on the last case and am hoping to get it right this time. But, what are the odds that this month’s parasite is from the same genus as last month…..?

First, a few alternate parasitic causes of hematuria in a man who has visited Corsica and swum in many rivers:

Trichomonas: a protozoan parasite with worldwide distribution that is mainly transmitted by sexual contact and often asymptomatic. Its lower genitourinary tract symptoms can present as hematuria in males. I imagine Corsica could be a place where a vacationing man might contract such a parasite…..but we heard no mention of illicit sexual behaviour.

Ascaris lumbricoides: this was my wrong answer to last month (uggh!), but I did find a case review presenting w/ painless hematuria after passing a worm from the urethra, despite Ascaris rarely being found outside the alimentary tract. It does have a worldwide distribution and is associated with poor sanitation, which could certainly be true surrounding campsites.

Neoplasms: some would argue that cancer is the crudest form of a ‘parasite’ and can certainly present with painless hematuria when affecting the urinary system. But, not a true parasite.…so, on to my best guess:

Schistosoma haematobium – which shares much of its life cycle with the other schistosome species; penetrating the skin, migrating to the lungs, pairing with a mate in the liver, but it’s path diverges when the mated haematobium pair migrates and sets up shop in the venous plexus of the bladder; causing egg deposition in any of the urogenital organs (and not the liver, as with S. mansoni). With time, this can lead to granuloma formation and fibrosis, and calcified dead eggs in the bladder wall cause rigidity and obstructive uropathy, leading to hydronephrosis. PD-7 also mentions damage in the form of ulcerative lesions in the female genital tract, which unfortunately enhances susceptibility to HIV infection.

  1. haematobium is currently listed as prevalent in most parts of Africa, some of the Middle East and now also found in Corsica, dating back to 2013, when over 100 original cases were linked to swimming in its Cavu River. The assumption was that S. haematobium had been introduced to Corsica by an infected migrant individual. When whole genome sequencing was done on ova from the original outbreak, they found that many of the parasites were a hybrid between S. haematobium and S. bovis (a schistosome species found in cattle on Corsica). A few years later, in 2015-16, a few more cases appeared of the same parasite strain as from 2013. There was speculation as to how this ‘outbreak’ could persist through multiple years without either an animal reservoir or longer survival of infested snails since the free larval stage can’t resist the environment on its own. Both temperate and tropical schistosome strains have been shown to survive the colder temperatures, when infecting locally adapted Mediterranean molluscs (Bulinus truncates snails) on Corsica. This could explain the maintenance of schistosomes from year to year but is unlikely to explain how they later appeared in the Solenzara River (included in this man’s bathing sites), which is separate, but adjacent to, the Cavu river. It is now felt that reseeding of the river(s) by one or more infected bathers, is the most likely cause of the endemicity of S. haematobium on Corsica. I hope that my summary above correctly interprets the information I gleaned from my readings and do apologize if not.

 Diagnosis can be made by finding eggs in urine sediment microscopy, but these may also be seen in stool and rectal snip specimens; also used is urine PCR and serologic tests for schistosome glycoprotein antigens as well as antibodies; bladder biopsy and histology may show presence of ova associated with granulomatous tissue or calcification.

Treatment in PD-7 is listed mainly as Praziquantel, which in acute infections is given after a short course of corticosteroids. This drug alters the tegument structure of adult worms and increases calcium ion permeability and influx, resulting in muscular contractions and subsequent paralysis. This damage also induces a host immune response to parasite antigens. In parts of the world, Praziquantel is now being used in mass-drug treatment programs for intestinal helminths, lymphatic filariasis, and onchocerciasis. 

Many thanks for prompting yet another deep dive into parasitism. I eagerly await your next ‘parasite reveal’……

Kimona, from southern Vermont, where it is a balmy 41’F (5’C) and sunny skies

Felix writes:

Dear Twip Team

I hope I am Not to late as I am just writing on the 16th of February. My initial guess of Urogenital schistosomiasis led to some research into the parasitic situation in Corsica. Eventually I stumbled across the paper by Rothe et al that describes the case.

I am really looking forward to this episode to hear some more interesting facts about the topic.  

Greetings from Germany


Daniel writes:

Hello Vincent, Daniel, Christina and Dickson!

My name is Daniel. I am a medical doctor working in an emergency department in a South African Hospital.

Thank you for your entertaining and informative podcasts! They have stimulated a strong curiosity in parasites, as well as, other microbes in me. Please keep them coming.

I think my guess is probably late but here it is.

On hearing of a patient presenting with painless haematuria who has had exposure to fresh water sources, this immediately brought to mind Schistosoma haematobium. 

I worked for a year in an Anatomical Pathology Department where we saw many cases of Schistosoma ova in histological specimens in various organs specimens, including bladder, genital tract organs and intestinal biopsies.

I did not know of cases in Corsica. When I did an google search I was suprised to see an article by Roth, Zimmer and Boissier entitled “Developing Endemicity of Schistosomiasis, Corsica, France”. 

In this article the authors describe the case history of a 49 yo male from Germany who developed painless, macroscopic haematuria after swimming in multiple rivers in Corsica.

According to the article bladder biopsies revealed Schistisoma ova which were also seen in urine sediment microscopy. These showed a terminal spine resembling those of S. haematobium. 

Interestingly DNA samples of the ova showed a typical signature of S. haematobium while a  mitochondrial marker showed a typical signature of S. bovis. Which indicated that this organism was a hybrid which had been found to be responsible for an outbreak in 2013, associated with the Cavu river.

So my guess is Schistosomiasis. In particular, I believe the case that was presented in the podcast is the same case in this article which describes a man infected with a hybrid species of S. haematobium and S. bovis.

Thank you all again for you wonderful podcasts