Case guesses

Chris writes:

Dear TWiP ternion,

It is a humid 27°C at the Morningside campus of Columbia University, and I am taking a quick break from the bench to write you. I was introduced to the TWiX podcast family by a lab mate about six months ago, and I have since worked through the entire backlog of TWiP, most of TWiM, and have kept current with TWiV and TWiEVO. Now that I have run through the past episodes, I think it’s time that I take a guess at one of your case studies. I work with P. aeruginosa biofilms and have been fortunate enough to not have any “personal” experience with parasites, so it is probable that my guess will be entirely off-base…but it can’t hurt to try.

I believe the patient from TWiP episode 112 may be suffering from a case of CNS schistosomiasis, brought on by a Schistosoma trematode. The “usual suspects” are S. hematobium, S. mansoni, and S. japonicum. Generally, México isn’t a country in which this condition is thought to be “endemic” (source), but Daniel seemed to make it very clear that this patient spent his ten-month stints in the southern portion of the country, which is quite close to other regions where it is more common (Venezuela, Dominican Republic, and Puerto Rico, for instance).  

The parasite’s eggs are introduced to fresh water through the feces and/or urine of an infected person, where they invade an intermediate snail host (as many trematodes do), and are later able to survive in a free-swimming larval state before encountering and penetrating the skin of a human host. Once inside, the worms sexually mature, pair up together (isn’t that romantic?), and settle down inside the blood vessels. Females lay eggs, which travel throughout the body, most commonly ending up in the bladder, lungs, heart, digestive system, and sometimes, in the CNS and brain (source). The WHO indicates that agricultural workers are part of a high-risk group that are regularly at risk for schistosomiasis. (source)

Anemia, urinary incontinence, and bowel issues are commonly associated with schistosomiasis, and they can either present with an acute onset, or can be chronic in nature, taking years to be notable enough to raise serious concern. I suspect the numbness and severely reduced function in the legs is due to the spinal mass mentioned, which would be caused by the presence of schistosome ova (which are responsible for the pathology associated with these parasites) which can spur granuloma formation in that area. In fact, I found a publication from the CDC outlining cases of spine/brain-associated schistosomiasis in Peace Corps volunteers, which closely mirrors the symptoms described in the case study. (source) It is worth noting that almost every other case I encountered in my PubMed searches also mentioned that standard blood screens also returned unremarkable results.

Diagnosis is achieved by urinalysis and examination of stool for the characteristic eggs, blood test for presence of schistosome antigens, and biopsy of lesions to look for the presence of worms and/or eggs. The tricky part is, there may not be evidence of the worms at one area at any given time. I would collect urine and stool samples for a few consecutive days, order blood tests to look for associated antigens, and if it is possible, obtain a biopsy of spinal lesion in hopes of observing granulomas containing schistosomes and/or their eggs.

Treatment seems to be a combination of praziquantel and corticosteroids. Since the praziquantel only kills the adults, it is necessary to continue to monitor the patient and probably re-administer the drug periodically to ensure that the successive generation is killed. I’m not sure what to do about the brain, but I would presume that it is best to tackle this active infection first and then reinvestigate (with a neurosurgeon, perhaps).

I am unsure if treatment for the schistosomes will lead to a complete restoration of function and feeling in the legs, as it seems like the spinal mass would need to be removed or reduced in order to return to normal function.  

If my guess is wrong, I still got to spend an hour break from the bench absorbing a bunch of fascinating information about these parasites. Who could complain about that?

Thank you for the amazing podcast—and Dr. Racaniello, I will see you in Spring 2017, when I will have the pleasure of taking your virology course!


Chris (Dietrich Lab)

Christopher Beierschmitt

B.A. Candidate in Biology | Columbia University

Wink writes:

We had a case in Atlanta of a man with cysticercosis in the spinal cord. That’s my guess for this week’s case. We had a brave neurosurgeon who operated successfully on the cord.

Wink Weinberg

David writes:

Dear Docs,

After getting last week;s diagnosis incorrect (although strongyloidiasis was the next choice on my list), I hope to have more luck with this week’s guess.

The 59 year old gentleman from Mexico (an area highly endemic in the disease that I am about to guess) seems to have contracted an unfortunate case of neurocysticercosis, perhaps contracted somewhere during his farming days in Mexico. Symptoms of the disease may not develop for years with this parasite but when they do they can have dire consequences: in this case, pork tapeworm larvae have travelled to the spinal column, and it there the damage is done.

The larvae blocking cerebrospinal fluid and pressing on the spinal cord are major contributors to the man’s symptoms – back pain, weakness, and loss of mobility due to the spinal cord damage, and hydrocephaly due to the problem in recycling CSF. The lesions in the T9/T10 vertebrae via MRI help seal this diagnosis.

Treatment of neurocysticercosis is tricky – surgery may be perilous since the parasites are so close to sensitive nerves. Praziquantel is the most common drug used in treatment of neurocysticercosis, along with albendazole combined with corticosteroid to reduce inflammation. However, this will only kill the parasites – for complete removal, surgery is required. Hopefully the man made a full recovery.

Thank you once more for the informative podcasts


Dave P.

Emi writes:

TWIP Trinity,

Let’s start with a stool sample (O&P). This won’t give us any definitive answers, but can help form a clearer clinical picture, with minimal invasiveness. I am particularly interested in any gravid proglottids or eggs of the Taenia solium variety (15% Taeniasis-Cysticercosis coinfection), and amoebic cysts. Sounds like you did a CBC, but I didn’t read anything about eosinophils…

I would also like a lumbar puncture, ideally some fluid from the mass lesion if that doesn’t pose too great a morbidity threat. My guess is it would reveal cysticerci of Taenia solium, which the patient probably picked it up in Mexico. He would not have had to personally dine on undercooked pork (consuming cysticerci does not lead to cysticercosis!!). Rather, he likely acquired T. solium eggs fecal-orally from unclean water or uncooked veggies. Treatment is Albendazole, Praziquantel, and Dexamethasone for the inflammation that occurs during die off. Hopefully this cocktail works, so surgery and excision are not necessary. If the patient is also hosting a mature tapeworm, it will be evacuated following administration of Praziquantel. In parasitic diseases 5th edition, Dickson says, “All patients selected for treatment with antihelminthic drugs should undergo a prior ophthalmologic exam in order to rule out intraocular cysts,” so let’s do that first.

Would you ever initiate a prophylactic antiepileptic drug?

Additional possibilities: other cestode infections seem unlikely due to epidemiology and presentation (neuro hydatidosis, cerebral sparganosis). Couldn’t find a spinal case of CNS toxoplasmosis without severe immunosuppression, so that’s not a likely candidate either. Cerebral amebiasis is possible but no dysentery was reported and the onset tends to be much more abrupt.

Thanks for the great podcast! A welcomed break from my pre-med organic chemistry summer school.



Elise writes:

Dear TWIP Trifecta

How are you? After some torpor-inducing humidity earlier in the week, we seem to be in a patch of excellent weather in New York: sunny and 82 F (28 C).

I have an attempt at a diagnosis for the 59 year-old patient in TWIP 112. I believe he is suffering from spinal schistosomiasis. His symptoms are consistent with this particularly unpleasant form of schistosomiasis, especially the ones involving  his progressive lower body weakness and incontinence. Schistosomiasis can manifest itself in many, many parts of the body, and while this is not  extremely common, it can show up in the spinal cord where it can take a number of forms, among them granulomas. I believe the mass that was observed at the T9/T10 vertebrae could be one of these.  It can also be difficult to diagnose this form of schistosomiasis because the disease can be asymptomatic or progresses slowly, and finding evidence of the parasite can be tricky. (Rectal biopsies and stool examinations often don’t reveal eggs.)  The best diagnostic tool is to perform a biopsy of the granuloma if one is spotted on an MRI.

The patient is  a good candidate for encountering schistosomiasis because of his frequent extended trips to Mexico and his time spent in rural environments when he is there.

I had some difficulty with a differential diagnosis. The patient’s symptoms could indicate a number of neurological or spinal problems or multiple sclerosis. IN addition his primary symptoms resemble  Cauda Equine Syndrome (which actually might have been a more frightening diagnosis than spinal schistosomiasis).

As always, thank you so much for your wonderful podcast and all of your work.

Jeff writes:

Hello TWIP Doctors,

The weather here is South San Francisco is 55F and overcast/fog.  Quite strange for a late June day!

This is a quite interesting case. I would like to see an O&P, although I am not sure it will be informative to the case presented.  In any CNS infection a cestode would be the most likely suspect.  Neurocysticercosis is pretty difficult to diagnose and when suspected I would order an MRI or CT scan.  This is definitely an atypical case with no headache or seizures (although there is hydrocephalus), but I am going to venture a guess of neurocysticercosis due to Taenia solium.  Treatment would be with albendazole, but I would wonder if the patient would need to be monitored closely and have anti-convulsive or steroid given concurrently to anti-helminth treatment.  I would hypothesize that the muscle weakness is due to the inflammation of the spinal cord and may partially or fully resolve upon treatment.

Love the show and the case studies as it gets me to think outside my scientific focus!


Jeff Fairman, Ph.D.

Vice President, Research

SutroVax, Inc.

South San Francisco, CA 94080

Joella and Donny write:

Dear TWiPerati –

It is storming this evening in eastern Connecticut, not that comfortable at 20C due to the 97% humidity. We’re a recently married couple writing in for the first time. She is an MPH grad now at Brown University for a PhD in Epidemiology and he is an Infectious Diseases fellow at UConn. Thanks to each of you for this excellent podcast!

First guess comes from the wife who is a foodie and thought of corn smut, the Mexican delicacy often consumed with tortillas. The husband recalls a case report of a CNS lesion caused by Ustilago maydis (corn smut), however, that patient was severely immunocompromised. Also, it’s not exactly a parasite. Maybe on TWiF.

Post-polio syndrome could explain the chronic, slow decline in nerve function but not his imaging. We wonder if this could have an immune dysregulation component precipitating his disease.

Our guess is Neurocysticercosis, caused by larva of Taenia solium. Latin America has the highest incidence of cysticercosis which can cause a variety of problems in the brain. We suspect this patient has a malignant form, with parasites in the subarachnoid space blocking CSF flow through his cerebral cisterns and/or ventricles causing hydrocephalus. Taenia solium has also been reported to cause masses in the spinal cord, though this is “supposed” to be rare.

We could look for increased levels of antibodies in the spinal fluid compared to blood, but with hydrocephalus we worry a spinal tap could cause herniation and dramatically shorten our patient’s lifespan, so nevermind.

First thing to do is start corticosteroids to block inflammation and second an antiepileptic to block seizures. Ultimately, we think it will take some neurosurgery to remove the spinal mass and place a ventricular shunt. Then we can treat with albendazole or praziquantel.

That should do it, unless we’re wildly inaccurate.

Joella and Donny

Mike writes:

Hi Guys,

I’ve got it this time. The man has neurocysticercosis. YooHoo! But when I told my wife that I had the answer she said, “Let me tell you the story about flying pigs, how they go higher and higher into the sky trying to get to pig heaven. But what they don’t realize is that it is really cold up there and they freeze to death and fall to earth like hailstones. And one of those hailstones hit the man while he was working in his cornfield, penetrating his skull, plugging up one of his ventricles, and that’s what caused his brain to swell.”

What can I say. My wife is always right so I guess I’m going with porcine hailstones.

Mike from Oregon

Hi it’s me again,

My wife made me write that last letter but we all know she was wrong. The hailstone didn’t hit the man in the head. It hit him in the back because that’s where the mass was seen on the MRI.

OK gotta go. Mike

Iosif writes:

Dear Twip Trio,

My main guess for this case would be Taenia Solium. The extraparenchymal forms of neurocysticercosis can develop within the ventricles (leading to the hydrocephalus) and within the spinal canal itself which would lead to the symptoms that our patient is presenting with. The cysts forming in the spinal cord is exceedingly rare (1% of cases), but are more common when cysts are found within the subarachnoid space within the brain. The last hint of this diagnosis are the ” “ring-enhancing lesions” found within the MRI of the brain that Dr. Griffin probably tried to avoid saying. Treatment will be complex and may include VP shunting to fix the hydrocephalus, surgery to remove the cysts within the spinal cord, albendazole and/or praziquantel to kill of as many worms are possible, and steroids to reduce the inflammatory response to the cysts which would cause further damage to neural or spinal tissue.

Secondary Diagnoses: Toxplasmosis could also cause the neurological symptoms and the spinal cord findings; however, the patient is HIV negative. Unless there is another source for an immune deficiency, this is unlikely.

Schistosomiasis can rarely spread to the spinal cord and brain and cause a demyelinating syndrome that could present similarly. It is unlikely due to the area of which this patient is from and the fact that I would expect more common symptoms along with his presentation.

Echinococcus can also cause these findings and can be found in Mexico. I would expect either a mention of liver cysts, expectoration of salty mucous or a mention of dogs.

Non-parasitological diagnoses: Primary neoplasms such as Glioblastoma Multiforme, or ependymomas would be on my list. Metastasis from a whole host of cancers such as prostate, lung and melanoma like to spread to the brain and spinal cord.


Iosif Davidov

Hofstra Northwell SOM Medical Student

Class of 2018

Mark writes:

Dear Twip Triumvirate,

My guess is that gentleman has neurocysticercosis caused by the pork tapeworm.  Consistent with diagnosis are the mass lesion at T9-10 and hydrocephalus. Also he is from Latin America where this parasitic disease is common.  Most cases are asymptomatic and benign according to CDC website.  And if patient is symptomatic it usually manifests as seizures.   Treatment for this parasite is albendazole 15 mg per kg per day twice daily for 14 days after shunting csf fluid causing hydrocephalus. There are concerns inflammatory process could exacerbate symptoms by precipitation of inflammatory reaction, so dexamethasone  6 mg daily for 10 days may be added to therapy.  Spinal lesion and may require surgery?

Thanks for interesting case. Temp is 34 degree c day in Oklahoma, but heat index makes it feel more like 37 degree c plus.


Jaime writes:

Greetings and best wishes from Caracas, Venezuela. After an unusually severe, dry, and prolonged El Niño event, we are already going through a strong La Niña cycle, with plenty of rain and milder temperatures.

Again, congratulations for producing such a highly addictive, fascinating, and informative podcast.

Your current clinical case is certainly a difficult challenge for any clinician.

In a context other than a discussion on parasitism like TWIP, the first consideration of the differential diagnosis must include intramedullary tumors, such as astrocytomas or ependymomas, or else, extramedullary tumors such as schwannomas, meningiomas and neurofibroma; as well as other cysts (arachnoid, ependymal, or neurenteric cysts), sarcoidosis, and infections such as abscesses. Most patients end out undergoing a diagnostic biopsy procedure to confirm or rule out the possibility of a tumor.

However, based on the epidemiological history of this patient, spinal intramedullary cysticercosis by Taenia solium appears a good possibility.    

Intramedullary cysticercosis typically affects the thoracic cord, with a few cases involving the cervical and the lumbar cord. Its course is often progressive, worsening from weeks to years. Inflammatory reaction against the dead parasite is associated with perilesional edema, which can damage medullar parenchyma and therefore, worsen symptoms.

The characteristics of the lesion on MRI may help to differentiate between a colloidal or viable and a degenerating cysticercus.

A spinal tap often reveals increased CSF proteins, a low or normal glucose, moderate lymphocytic pleocytosis and eosinophilia. Cysticercal antibodies found in CSF either by ELISA or in serum by enzyme-linked immunoelectric transfer blot assay have good sensitivity and specificity in cysticercosis diagnosis.

Current treatment includes an initial course of the anti-parasitic drug Abendazole for those patients highly suspected of intramedullary cysticercosis and whose clinical courses are stable or when the lesions is considered surgically unreachable or multifocal. Moreover, Albendazole is often used with corticosteroids preoperatively, because its blood level could be synergistically increased by the latter. On the other hand, surgery is procedure of choice only when diagnosis is in doubt. Preoperative adjunctive treatment with albendazole is thought to be helpful to consolidate the lesion and thus induce a clear plane of dissection during surgery. Albendazole is normally used postoperatively as a regular treatment (15mg/kg/day) for 4 to 6 weeks, according to the idea that cysticercosis is a generalized disease with focal manifestation and additional undetected lesions cannot be ruled out completely.

I hope the patient had a successful resolution of his condition without permanent sequelae.


Emi writes: (case 111 guess)

Hello TWIPsters,

My name is Emily, and I’m new to the podcast. My credentials as a guesser are limited but relevant–TA’d a university course on Parasites and Pestilence and am headed to London next year for a Masters in the Control of Infectious Diseases. Let’s see how I do!

When I found out that the patient had minimal relevant contact and no recent travel, my mind shot to Strongyloides. Watery diarrhea, albeit mucosal, and can recur many years following initial exposure (thanks to autoinfection). But, we would expect to see bouts, whereas our patient suffers from continuous diarrhea. Not Strongyloides stercoralis.

Not Entamoeba histolytica. While amebiasis can start with watery diarrhea and progress to bloody diarrhea, 10 days of continuous non-dysenteric diarrhea seems unlikely.

Not Giardia lamblia either. Her diarrhea isn’t fatty.

While I’m at it, I’ll also rule out Trichuris trichiura and Trichinella spiralis (sorry, Dickson). Trichuris generally occurs in children. It would explain her loose stools throughout the night, but the shear volume and duration of reported diarrhea make it an unlikely candidate. Trichinella can result in a few days of diarrhea, but the rest of the picture doesn’t fit–particularly her lack of undercooked meat consumption.

Although Cystoisospora belli results in watery diarrhea, it tends to be foul smelling. The parasite is usually picked up during travel to tropical regions. Out.

Our patient eats raw fruits. Berries? Raspberries have been the source of US outbreaks of Cyclospora cayetanensis, a fecal-oral parasite. Infection does result in watery diarrhea. I would be surprised, though, if she were the only one in her home to contract it. Plus, the typical course of diarrhea is quite a bit longer than 10 days. Unlikely candidate.

Capillaria philippinensis is quite rare (unheard of in the US), and results from undercooked fish, of which there was no reported consumption–still, gotta be thorough with the parasitic ddx.

This brings us to Cryptosporidium spp. According to our friends at Medscape, “Temperature higher than 39°C is not characteristic of cryptosporidiosis,” so that fits. Did find a case report of one individual with hypoactive bowel sounds. Check! To quote from Dickson himself in Parasitic Disease 5th Edition, “Cryptosporidiosis is self-limited, lasting from several days to one month.” About the right length of time. Where she contracted it, and why that rash has developed, I can’t say.

In practice, there’s no real need to narrow it down–can wait for the suggested tests to come back–but I’ll hanker a guess: Crypto!

Anthony writes:

For whatever my opinion is worth, of course you and Professor Despommier had been great on TWiP, but the addition of Dr. Griffin has made the show even better yet.  I now have to wonder what Dr, Arthur Conan Doyle might have accomplished if he’d stuck with disease and not wandered off to fiction.

On a separate note, in one of the shows you mentioned Benny Tudino’s pizza in Hoboken (though not by name).  I was in the place once maybe 25 years ago and I pegged it as a tourist trap.  

If you’ve ever the time — and the spirit of adventure to go past the Disney version of Jersey City at Noport — the local pizza joint that I went to is Gino’s on Central Ave. near Charles St.  I’ve been a vegan for almost 20 years, but I still remember the phone number.  I go past regularly and it’s always busy, so I guess that they still are good.

When you added Dr. Griffin to TWiP, my thought was that you’d found a great angle — human health — to increase audience size and depth.  For myself, I prepared for disappointment.  My (admittedly superficial) impression is that physicians are trained to practice and — like  musicians and athletes — don’t articulate well what it is that they do.  With Dr. Griffin and his case thought puzzles, clearly I was very wrong.  That’s when I remembered that Arthur Conan Doyle was a physician.

Dr. Despommier’s perspective is something very valuable.  Even his mistakes can contain insight.  In one show he confused Monotremes with Insectivores.  Since I heard that I’ve been wondering why Insectivores are called that.  After all, they do eat a range of arthropods, earthworms, slugs, amphibians and basically any animal small enough for them to kill.

Thank you again for your great shows.

Alex writes:

I saw this Frog Applause comic by Teresa Burritt, and…thought of you.  

William Walter Cort

Thanks for the education and entertainment.

Best regards to all at TWiP.

Alex, in South Orange County, CA

P.s. We’re having a hot spell today and tomorrow, expected highs of 33C.  Even so, it’s a considerable relief from last Monday’s (20 June) high of over 43C.

Anthony writes:

In a recent TWiP Professor Despommier noted that coprophagy can be due to some deficiency in the diet.  This is certainly true.  (If memory serves me correctly, it can be demonstrated that in model animals coprophagy results a predictable number of days after the removal of particular essential nutrients from the diet.)  More often in animal care it’s believed / assumed that coprophagy is induced by blood in the feces.  It occurred to me that for parasites using a fecal – oral route, causing a bloody stool may provide the direct benefit of transforming their transportation from a slow train to an express.  Are there any parasites that cause blood in the feces where this action is “extra?”  By that I mean damage done beyond that to be expected from activity necessary for feeding / breeding — blood letting just to encourage coprophagy?

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