Case guesses:

Chris writes:

I am enjoying these increasingly challenging cases with either a lot of noise or essential data points. 

As a famous infectious physician often repeats on an edutainment podcast, Occam was not a physician. This patient has many things going on, and the symptoms he is experiencing could be attributed to different processes. A COPD exacerbation could explain the acute respiratory and hemodynamic symptoms including shortness of breath, dyspnea on exertion, orthopnea, and white sputum. This respiratory episode and/or associated treatment could have exacerbated his renal condition. Nausea, vomiting, anemia, elevated BUN, and creatinine are consistent with progressive renal failure, especially with missing a dialysis appointment. The eosinophilia could be due to COPD.  

The generalized rash and pruritis seem to be transmissible within the dialysis clinic so it argues against a process secondary to renal failure. My guess would be scabies, another potential and likely reason for the eosinophilia. My gut tells me I am overlooking something, but I cannot put a finger on it. I am looking forward to hearing the way Dr. Griffin approached this case. 


(please pick my name!) 


Christopher Hernandez

MPH 2020

Infectious Diseases and Vaccinology 

University of California, Berkeley

Joshua writes:

Dear Doctors Despommier, Griffin, Naula and Racaniello,

Congratulations on your wonderful and engaging science communication work! Some months ago, thanks to a mention of TWIV on my then-favourite podcast, “This Podcast Will Kill You” (TPWKY), I discovered first TWIV and then TWIP, and they rapidly become all engrossing, though I trust they have proven symbiotic, rather than viral and parasitic. Since this happy accident, I have abandoned most of the other podcasts I had been following (except for TPWKY), as I have been listening to many back episodes of first TWIV and then more recently of TWIP, though I still have hundreds to go.

It is currently 18°C, at the end of a sunny day which reached a high of 24°C (I have no idea what that is in Fahrenheit) in my home city in northern Tasmania, as we enter into late spring. The school year has almost ended, and the Year 11 and 12 students are about to sit their final exams; I have been a high school teacher for over a decade, but the pandemic and my consequent burgeoning interest in public health is making me consider a possible career change.

Tasmania has been largely spared the worst of the pandemic: our State border was closed in mid-March 2020, for the first time since 1919, at the same time as the national border was also closed, and we only fully reopened to the Mainland of Australia in mid-December 2021. As vaccination rates were very high by then, despite a deluge of cases since, less than two hundred deaths out of a population of half a million have been recorded. I remain profoundly grateful to all the virologists and other scientists who developed the COVID-19 vaccines, particularly the Pfizer and Moderna, which I have received; I’ve had my fourth dose, and so far as I’m aware I still haven’t had “the ’rona” as we Aussies call it. The terrible and needlessly high death toll in the USA is a tragedy. I do hope that Dr Despommier has made a full recovery by the time this email reaches you all.

But on to the case, who seems to be suffering from two parasitic maladies, in addition to his chronic health problems! It was immediately obvious, once track marks between fingers was mentioned, that the itchy rash suffered by the unfortunate victim was scabies, which he has endured for three months – why did the dermatologist not recognise this, instead of blaming it on a food allergy? I well remember my horror when a flatmate many years ago revealed he had that infestation – thankfully I avoided catching it, but my flesh still creeps at the thought. The other dialysis patients mentioned must also have contracted this pruritic pest from exposure at the treatment clinic – my sister, who is a nurse, and with whom I’ve just discussed this case, opined that the dialysis ward should have been cleaned more thoroughly.

As to the acute condition that has developed over the week prior to seeking treatment, having downloaded and consulted a certain free pdf well known to you all, I initially thought that the gentleman, being originally from Hong Kong, may have enjoyed tasty but undercooked crab, crayfish and crustacea, which are dangerous delicacies enjoyed in some Asian cuisines, resulting in an infection with lung flukes, either Paragonimus westermani or P. kellicotti (the latter being endemic to the USA). However, paragonimiasis, while characterised by shortness of breath, a cough, diarrhoea and eosinophilia, is not characterised by nausea and vomiting. Moreover, this disease would result in bloody sputum, not “white” sputum.

Therefore, I changed my diagnosis to Wakana, or “green vegetable” disease, reported from Japan as occurring between the end of August and the middle of October, which is a form of hookworm infection contracted by accidental ingestion of the parasite Ancylostoma duodenale, and is described as resulting in nausea, vomiting, coughing, difficulty breathing and eosinophilia. This diagnosis better suits the case described, rather than lung fluke infection.

To treat the scabies, lindane or permethrin cream could be applied, or ivermectin used (if any is still available, supplies having been misused by the misguided), but I leave it to Dr Griffin to carefully select whichever treatment is safest for this patient, who has multiple chronic conditions. To treat the hookworm, either albendazole or mebendazole could be used, as the doctor will decide.

Thank you again for all that you do, and for your kindness, patience and unfailing good humour.

Yours sincerely,


Fiona writes:

Hello Twiplets,

I am Fiona, from the currently not so sunny, but still beautiful, seaside town of Oban in Scotland. I am a Clinical Fellow working with Public Health Scotland and am also studying for a  Diploma in Tropical Medicine and Hygiene with the University of Glasgow, which is how I was introduced to this wonderful show by our tutor Christina Naula. 

I feel a bit of pressure to get this right knowing she is one of the hosts of this show, and my classmates may also be listening in, but am inspired to give it a go to develop my learning and confidence! 

I believe this gentleman has been infected with Strongyloides stercoralis, which has resulted in disseminated strongyloidiasis. His significant medical history including being immunocompromised puts him at higher risk of severe infection. His respiratory, gi and dermatological findings are also suggestive of this although diagnosis can be difficult. The larvae may be seen with stool microscopy but multiple samples may be required. It is likely the other 3 patients mentioned have also contracted this infection.

Ivermectin is the drug of choice although immunocompromised patients can apparently be refractory to treatment and multiple courses may be required. It is also worth noting that ivermectin dose should perhaps be considered with caution in this patient due to possible liver impairment secondary to his chronic HBV infection (although LFTs not shown) as it is heavily metabolised in the liver, however this shouldn’t prevent him from receiving the drug. 

I hope I did my Glasgow Tropical Med Diploma team proud and if did receive the prize I would donate it to my local Hospital library as they lack any parasitic or tropical medicine books, but we do get exposed to travellers from all over the world and think your book would be an invaluable resource for other clinicians and med students.

Thanks for all your hard work, banter and entertainment – especially when I have to make the long commute to Glasgow from Oban (6 hour round trip!) for work every couple of weeks. I’ve learned a lot not just about parasitism but other interesting facts – including fishing! 

Warm regards,


PS I hope Dickson is feeling better soon 🙂

Jason writes:

Greetings Twip hosts!

 It is a cool 7 degrees Celsius in Seattle, Washington. The tide is high and the Puget Sound is choppy as I write this.

As to the parasitic diagnosis of the man from Hong Kong with multiple comorbidities, this patient appears to be suffering from a case of Strongyloides stercoralis hyperinfection.  

This patient was probably infected with the Strongyloides nematode many years ago while residing in rural Hong Kong. The helminth is normally acquired via the transcutaneous route, after which immunocompetent patients may enter a chronic infection state. During chronic strongyloidiasis, patients typically exhibit nonspecific symptomology such as intermittent diarrhea and constipation. It is during this time that the spread of the disease is normally held in check by the host’s immune system.

Our patient likely received steroid therapy for a recent episode of acute hypoxic respiratory failure secondary to COPD, at which point chronic strongyloidiasis – no longer held in check by a robust immune system – shifted into a hyperinfective phase, in which the L3 larva stage of the parasite autoinfected the patient en masse. The patient now exhibits a constellation of signs of Strongyloides hyperinfection, including eosinophilia, a cough producing white sputum, a diffuse rash which may be either the result of an immune reaction to migrating worms or secondary bacterial infection, linear scabs between his fingers (larva currens, in this case), diarrhea, and shortness of breath.

While there are several high-tech methods to diagnose strongyloidiasis, the gold standard diagnostic method remains visualization of larvae, either in stool or in the duodenum itself. Effective tests include the Baermann concentration method, Harada-Mori filter paper culture, nutrient agar plate culture, or duodenal biopsy.

Once the diagnosis is confirmed, treatment with ivermectin should begin promptly. The 2021 Sanford Guide to Antimicrobial Therapy recommends 200 micrograms per kilo per day (by mouth) for two days. However, a 2019 paper published by Krolewiecki and Nutman in Infectious Disease Clinics of North America suggests that ivermectin therapy may be administered for an even longer duration in severe cases such as in hyperinfection, and the CDC page on Strongyloides states that ivermectin – in cases of hyperinfection syndrome / disseminated strongyloidiasis – should be given as follows: “200 mcg/kg per day orally until stool and/or sputum exams are negative for 2 weeks.”

 Worm regards,


Mark writes:

Hi TWiPpers,

My guess is that the patient in TWiP 210 has a hookworm infection.

That is consistent with the symptoms and signs and their ordering.  First there is a rash and itching as the parasite migrates through the skin, possibly with an allergic reaction causing the whole-body reaction.  (I think that might be consistent with the “symmetrical, raised rash” described.)  Then there are respiratory symptoms as the parasite enters the lungs.  Then there are GI symptoms after the parasite travels up the trachea and is swallowed, entering the GI tract.

Another possibility would be an infection with Strongyloides stercoralis, which has a similar progression, but the nausea and vomiting seem to be more associated with hookworm, presumably from the irritation that hookworms cause as they attach to the intestinal walls.

The most likely hookworm species for the US would be Necator americanus.



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

Highly regarded Sarcop-teachers,

We will try to be brief this time. The patient is suffering from a severe infection with the scabies mite Sarcoptes scabiei. The clinical signs of itching, erythematous papular eruption and lesions between the fingers point towards this diagnosis and are very typical. 

In this case, the patient’s immunosuppression predisposes him to a more severe presentation, which includes generalized erythema and blood eosinophilia. This is not uncommon in medical settings like dialysis units or care homes and these infections, like in this case, often present within the context of an outbreak. Also the fact that our patient obviously seems to have a parasitic disease which can be transmitted from patient to patient significantly reduces the list of possible differentials. We could not think of anything besides scabies, which fits the mentioned symptoms very well. 

Most other symptoms of the patient may be due to his extensive PMH (COPD exacerbation, CAP, etc). It’s easy to think that dialysis can replace kidney function, but patients with end stage renal disease commonly have several comorbidities and, without transplant, their prognosis is not great. This patient has a life expectancy of 4,8 to 5,7 years, as compared to 16,3 to 19,9 for his peers (U.S. Renal Data System).

Treatment is with permethrin cream or oral ivermectin. Additionally, a hygiene plan should be implemented, which could be difficult considering the functional status of the patient and the lack of social support. Furthermore, some form of outbreak management at the dialysis unit is probably in order.

We are very happy to hear in your other podcasts that Prof. Despommier is doing well. Thank you for this great case. All the best, 

Michelle and Alexander from the First Vienna Parasitology Passion Club