Case Guesses:
Frithjof (Freed-yoff) writes:
Dear Professors,
Greetings from sunny Caen, Normandy! To pronounce the name of this charming city, try saying “Kah(n)” while holding your nose; it adds a bit of local flavor! 😀
Regarding the case of the pregnant woman from northern Tanzania presenting with bloody diarrhea, the most likely causative agent is Schistosoma mansoni. To confirm this diagnosis and rule out other possibilities such as amoebiasis, stool microscopy is recommended.
Treating schistosomiasis during pregnancy poses certain challenges, as praziquantel is generally contraindicated. Each case should be carefully evaluated, and the risks and benefits of treatment thoroughly discussed with the patient. Alternatively, oxamniquine may be considered as a treatment option.
In accordance with the UN’s Global Goals, we should work toward providing safe and reliable sources of drinking water for all, to help prevent cases like this from occurring in the future.
WORM regards
Frithjof (“Freed-yoff” – please do not cover your nose while pronouncing my name)
proud owner of a signed copy of “Parasitic Diseases”
Paul writes:
My signed copy of Parasitic Diseases, Seventh Edition was very helpful in this case.
The statement “Stool studies are sent and Ockam would be confused but Dr. Hickam would know what to do” suggests confounding findings.
Entamoeba histolytica seems the likely pathogen with the clinical history of sticky, bloody stools. There are several non-pathologic Entamoebae which could be seen on stool exam making diagnosing E. histolytica difficult with microscopy alone.
The differential diagnosis would include Cryptosporidium but it’ s clinical presentation of watery non-bloody diarrhea makes it less likely. Another possibility would be Giardia but it’s clinical features of steatorrhea (stools with fatty or oily characteristics) and no bleeding make it less likely.
Microscopy alone is not very effective in making the specific diagnosis for these organisms. Multiple species of organisms might be present. NAAT testing on stool specimens can identify the specific Entamoebae involved.
My diagnosis is E. histolytica. Metronidazole is the antibiotic of choice which is considered safe in the second trimester of pregnancy.
Thanks for all you do.
Paul
John writes:
Greetings esteemed para-nauts, I’m still seeking to win the book and good luck to everyone.
The clue allowed me to consider Giardiasis despite it not being commonly associated with blood in the stool. Symptoms do match dehydration, greasy stools, fatigue, and spread by contaminated water endemic to this region. Stool samples can be used for diagnosis too.
Leaning on Hickam, I found another stool diagnosable parasite endemic to the region with Schistosomiasis, something Dickson would have no doubt suspected and perhaps referred to as blood flukes. This would match up with anemia and in severe cases damage to the intestinal walls can lead to bloody stools. The elevated creatinine levels can be a concerning sign of chronic kidney disease associated with this parasite.
Praziquantel is a typical treatment for Schistosomiasis and metronidazole and tinidazole are antibiotics effective against Giardia. While Giardia can go away on its own, due to the pregnancy I could see reason to go ahead and treat that too and hydrate. I would try to communicate best methods to deal with contaminated water sources to prevent recurrence for the whole family.
Cheers and thanks for the great show
John
Ben writes:
Dear Twippers,
My guess is Schistosomiasis and a soil-transmitted helminth.
Regarding soil-transmitted helminths, Perera et al. (2024) state: “In the gut, the “weep and sweep” response predominates, which is defined by increased mucous production and smooth muscle contraction (79).” This could explain the sticky diarrhea. The Schistosomiasis could account for the subsequent bloody stool and elevated creatinine. Both could contribute to the low hemoglobin. I am tempted to walk upstairs and ask a colleague who works on Schistosomiasis co-infection but that feels like cheating.
Sincerely,
Ben in Liverpool (returning champion)
Perera DJ, Koger-Pease C, Paulini K, Daoudi M, Ndao M. 2024. Beyond schistosomiasis: unraveling co-infections and altered immunity. Clin Microbiol Rev 37:e00098-23.
https://doi.org/10.1128/cmr.00098-23
Jay writes:
Dear TWiPosomulae,
We’re told that Ockham would be confused but Hickam would have no problem. So there is more than one disease process going on here. This being TWiP, I assume that means two or more parasites. A recent review of parasite-endemic areas showed that approximately 10% of pregnant women are infected with 2 or more intestinal parasites.[1]
The greasy stool that is difficult to wipe clean is virtually pathognomonic for giardiasis. That’s parasite number one, and that may be what was detected in her stool sample. However, giardia is not known for causing bloody stool and anemia. Based on high prevalence in the region, I suspect the second parasite is schistosomiasis, likely mansoni. Getting water from the river puts her at risk. Her son and husband, if they are not spending time in the river water, avoid exposure to the circariae of schistosoma. There are mass drug administration campaigns (MDA) to help decrease schistosoma infection in endemic areas. If the most recent MDA campaign occurred when she was pregnant with her first child, she might have been deemed ineligible for praziquantel. Praziquantel appears safe in pregnancy based on my cursory literature review, but I suspect many MDA practices exclude pregnant woman.
The other interesting question that comes up here is immune modulation during pregnancy. Not surprisingly, it’s more complicated than the simplified view that pregnancy is an immune-compromising state.[2] I need to start listening to Immune.
Excellent case. May your great work continue to flow like a river.
Jay
[1] Mohan S, Halle-Ekane G, Konje J. Intestinal parasitic infections in pregnancy – A review. European Journal of Obstetrics and Gynecology and Reproductive Biology, Volume 254, 59 – 63
[2] Mor G, Cardenas I. The immune system in pregnancy: a unique complexity. Am J Reprod Immunol. 2010 Jun;63(6):425-33.
Jay Gladstein, M.D. | Chief Medical Officer
APLA Health & Wellness
Los Angeles, CA
Angela writes:
Hello from Bristol, UK
The weather here is cool but clement with a warm, sunny day forecast for tomorrow.
I have recently started listening to your podcast because I like learning about parasites. I intend to send in guesses until I win a book.
My guess for the mystery parasite from TWIP 259 is Entamoeba Histolytica.
I asked google what parasites are a problem for pregnant women in East Africa which gave me some relevant pub med articles. Then I looked for ones which could be caught from dirty water, which would cause internal bleeding and which would produce asymptomatic cases.
I think this patient was infected with Entamoeba histolytica from drinking river water. Her family members might have asymptomatic infections. I think her pregnancy made her more vulnerable because it weakened her immune system. The raised creatinine levels could be from kidney damage, maybe a renal cyst.
Wikipedia tells me that a direct fecal smear can be used for diagnosis but a PCR would be needed to differentiate entamoeba histolytica from entamoeba dispar.
I would treat the asymptomatic family members as well as the patient to avoid future transmission. I would avoid the nephrotoxic treatment option as this lady’s kidneys are already not doing great. I’d also not use the one that is not recommended for women in early pregnancy.
I would use paromomycin as wikipedia tells me this treats amebiasis and is okay for pregnant women.
I hope I would not have killed this patient.
Justin writes:
Hello dear hosts,
In the case of the pregnant woman from northern Tanzania my first thought jumped to Cryptosporidium, but there are so many diarrheal parasites to consider. For bloody, sticky stool perhaps Entamoeba would be more likely. Other options would include whipworm, Strongyloides, and Giardia. Giardia seems unlikely since no mention of foul-smelling stool and Strongyloides would likely result in a noticeable rash.
I think the most likely cause of this infection is an Entamoeba species, possibly with co-infection of whipworm, considering the mention of Hickam’s dictum.
Hoping I am at least in the general vicinity of the answer and hoping to win a book one day.
Thank you all,
Justin
J writes:
Good afternoon TWIPSTERS.
This poor woman sounds like she picked up two parasites. Most likely giardia and e.histolytica. Here’s my logic: River water in east Africa, home to both bugs. Pregnancy increases susceptibility. Afebrile, both check out. Greasy stool but also bloody? Not typical for any one parasite! Hickam nods and smiles. Creatinine is likely elevated due to her dehydration. Stool o and p should be diagnostic! Treatment? Metronidazole is usually safe in pregnancy.
Awesome case. Thank you doctors for this amazing resource. I’ve listened to so many Twix episodes and it’s become a favorite part of each day. I wish my little NJ lab had more interesting cases like these!!
Thank you!
Clinical micro tech, J
Eyal writes:
Dear Vincent and the sages of the Microscopic Eukaryotes.
Greetings from Sydney Australia and the land down under. Where the rain has finally relented. The weather is nice and fresh, perfect to go outdoors and sleep with the critters.
For the case of the 32 year old pregnant woman from North Tanzania suffering from 3+ weeks of diarrhea, sticky stools, dehydration, and bloody stools.
She seems to be suffering from more than one parasite. As Daniel eludes to, exclusivity is not typical in natural infections, or in nature in general.
As the woman is pregnant, I would assume she would be immune deficient, which will allow infections she has built immunity for in the past to re-emerge.
Based on a google search, Schistosoma mansoni is the most common intestinal parasite in Tanzania. It fits the symptoms of diarrhea.
Although Schistosoma can cause blood in the stool, from my limited reading that will not be noticeable by eye. So for the bloody stool I would assume the culprit would be Hookworms which are also typical to the area and rural living.
For the sticky stool my guess based on prevalence in Tanzania would be Giardia lamblia. Although Entamoeba histolytica wouldn’t be my first guess.
As always, thank you all for the knowledge you share and all your advocacy.
I will leave you with a few pictures from the weekend’s hike to Mount Solitary in the Blue Mountains where I probably consumed a few protozoans myself.
Best regards,
Eyal, returning champion 🙂
Jason writes:
Greetings TWiP Hosts!
In the TWiP 259 Hickam Goes To Tanzania case, we are admonished to adhere to Hickam’s dictum in the consideration of the diagnosis. In other words, “It is possible to have two things” – tip of the hat to Dr. Griffin for that quote.
Our patient is a 32-year-old pregnant woman who lives in rural northern Tanzania and draws her household water from the local river. Now she is in the hospital, presenting with melena, hematochezia, dehydration, fatigue, low hemoglobin, and elevated serum creatinine levels. Based on her clinical presentation and environmental risk factors, the parasitic culprits that stand out in her differential diagnosis include a combination of nematodes and platyhelminthes, specifically, whipworm, hookworm, and schistosomiasis.
Whipworm, more formally known as Trichuris trichiura, is a member of Dr. Peter Hotez’s “Unholy Trinity” of soil-transmitted helminths, with hookworm and ascariasis rounding out the trio. Adult whipworms reside in the lower GI tract and can cause both anemia and hematochezia.
Hookworm in Africa refers to either Necator americanus or Ancylostoma duodenale. Adult worms of these species reside in the upper GI tract and can cause both anemia and melena.
Elevated serum creatinine is rarely caused by infection with soil-transmitted helminths, but it is known to occur in cases of schistosomiasis. As no genitourinary signs or symptoms were given in her clinical findings, infection with Schistosoma haematobium seems unlikely, but an index of suspicion should be reserved for Schistosoma mansoni adults residing within the mesenteric veins.
A thorough ova and parasite stool exam should be conducted to rule in or out the presence of these helminths.
Worm regards,
Jason
Seattle, Washington
returning champion
Albert writes:
Dear TWiP
My guess would be amoebic dysentery due to Entamoeba histolytica. Prolonged bloody diarrhea with sticky stools and no apparent systemic signs (fever) suggest chronic invasive protozoal infection rather than invasive bacterial enteritis like Shigella or Salmonella, especially that she’s HIV-negative.
Low hemoglobin could reflect chronic blood loss from colonic ulcers and elevated creatine points to pre-renal azotemia due to dehydration.
Her pregnancy may be a risk factor for contracting the protozoa and we need to be aware of the risk of preterm labour.
Stool ova and cyst examination should reveal E. Histolytica cysts or the characteristic trophozoites with ingested RBCs.
Since she’s in 2nd trimester, metronidazole for 7-10 days is the treatment of choice. Although older studies suggested risk of teratogenicity associated with metronidazole, more recent studies could find no strong evidence and therefore I would still use the widely available metronidazole in early pregnancy especially when the benefits outweigh any theoretical risk.
Looking forward to hearing the diagnosis and my name when that TWiP book prize comes up!
Warm regards,
Albert
Malaysia
Joseph writes:
Greetings to the tremendously terrific TWiP team!
It is your friendly neighborhood lab safety specialist from Cut & Shoot, TX. Since my last e-mail, I have been accepted into the Infectious Disease Epidemiology MPH program at Texas A&M. Part of the program is required field experience. I am currently volunteering with my local mosquito control department. They have a wonderful little lab and are doing some great surveillance on WNV and working with the state regarding pesticide resistance in mosquitoes. They are proactive in the notion that climate change may bring more diseases to coastal regions of Texas. On that note, a fun fact…in 2023, Texas had its first locally acquired case of malaria (P. vivax) in 30 years. A sign of things to come? We shall see, but I digress. I’d like to take a stab at the new case presented in episode #259.
Given the symptoms of the patient from Tanzania, I am going with the diagnosis of amebiasis caused by Entamoeba histolytica. The patient lives in an area with poor sanitation and high risk of contaminated water sources – in this case, river water. The bloody/sticky stool, weakness, and anemia would be caused by amoebic dysentery. The lack of fever ruled out Schistosomiasis. While the intro of this e-mail is longer than my diagnosis, I am hopeful that it lands me a physical copy of PD7.
As usual, I had a great time listening to the episode and working through Dr. Griffin’s case! I truly appreciate all that you do.
Kind regards,
Joseph Jacobs, MLA(ASCP)CM, QLSCM
Michelle and Alexander from the First Vienna Parasitology Passion Club write:
Dear Giardians of wisdom,
We believe that Dr. Hickam would astutely reconcile two organisms in the stool; one responsible for the consistency and one responsible for the blood. Sticky, fatty stools are characteristic for Giardia, while macroscopic blood would be typical for Entamoeba. Both species can be transmitted through contaminated water, and while many parasitic infections can lead to anemia, blood in the stool is rarely observed.
Metronidazole or Trinidazole should treat both organisms.
Thank you for this great case! All the best,
Michelle and Alexander from the First Vienna Parasitology Passion Club
Email:
Rich writes:
Dear hosts,
When I studied parasitology a few years ago I became interested in trypanosomes and the co-evolution of the APOL-1 gene and the parasite of sleeping sickness, Trypanosoma brucei, and I thought it might be a worthy topic for your TWEIVO podcast – or jointly with TWIP (I can imagine Daniel Griffin will have come across the parasite a few times!).
I remember Dr Dickson Despommier commenting that the person who gave his name to the species, David Bruce, never understood the regional variation in resistance to the parasite in Africa – and it turns out there are two main sub-species each with a different mechanism of resistance. You die of Eastern sleeping sickness T, brucei gambiense, but die with the western, T b rhodesiense…
The whole story seems very interesting including a split in the original parasite lineage, a red queen co-evolution of host and parasite and a balanced polymorphism as changes to a host protein, ApoL provide some protection – but at the risk of kidney disease (similar to sickle cell anaemia). African-Americans who express only the G1 or G2 APOL1 variants that provide Trypanosoma brucei gambiense resistance have 7–30-fold higher rates of several types of kidney disease – a similar model to Haemoglobin S.
One of the world leaders appears to be Etienne Pays – and I came across a recent summary paper he wrote:
https://www.researchgate.net/publication/363251611_The_Pathogenesis_of_African_Trypanosomiasis
Many thanks & please keep podcasting!
Rich
Megan writes:
TWIP 246 was a really enjoyable episode about Trichinellae. I hope TWIP will continue to include senior or retired scientists to talk about their work. Getting the summary of a lifelong career researching a subject is informative, inspiring and very helpful. Thank you Dixon Despommier.
I also wonder if the book Dixon was referring to was Robert Desowitz’s New Guinea Tapeworms and Jewish Grandmothers ?
Megan
Chris writes:
Hello Professors,
I was browsing around the internet and I found this paper that appears to suggest that papaya seeds were able to reduce egg infection load of Ascaris lumbricoides by ~64% in african children when it was added to their porridge. I know these papers tend to be full of bad methods/ pseudoscience but I can’t find any obvious faults with this one, I was hoping Dr. Griffin might have some input on it. Or does this look like a possible method to help with deworming campaigns
Best,
Chris
https://link.springer.com/content/pdf/10.1186/s12906-018-2379-2.pdf C
Valerie writes:
Are there non-successful ie non-parasitic/ almost cross species parasites that sensitize the consumer? Is the suppressive effect unique to known parasites as opposed to the many non-parasitic nematodes we interact with? The true parasites must be a tiny fraction of the nematodes we are commensal with.
Perhaps mice are not a good system for studying the diversity found in the human gut and the immune system brain axis that interacts with the organisms and complex metabolites produced in the gut.
How much gut flora is shared by mice and men? Is this unique to different geographical and economic populations? Is colitis more prevalent among the mobile global level of society?
Valerie
Tom writes:
Dear TWIP family,
I am shamefully behind on TWIP episodes but I just listened to episode 254 and I wanted to express my deepest condolences for the loss of Dickson. But what a legacy he leaves behind!
I have been an infrequent emailer, but I started listening to TWIP in my first year of medical school in 2013 and have listened to nearly every episode since (and the backlog before). I was in no small way inspired by Dickson’s incredible story telling to pursue training in infectious disease, multiple tours at the London School of Hygiene and Tropical Medicine and global health work which now includes working in Uganda to combat the ongoing mpox (and Ebola) outbreaks. While you may not have known it, the entire TWIP team has been with me from the start of my career and in part trained me to be the public health and infectious disease physician I am today. I’m sure I am one of many mentees of Dr Despommier’s whom he never had the chance to meet.
Many more condolences to Dickson’s family and friends. He will be greatly missed but not forgotten.
Best,
Tom McHale
Kampala, Uganda
Jason writes:
Greetings TWiP hosts,
I wanted to send you the In Memoriam piece I included in the recent Compass Journal from the College of Remote and Offshore Medicine.
He was one of my greatest mentors, though I never met him. May he rest in peace.
Sincerely,
Jason
Seattle
PS, the link to the full version of The Compass is below
Jason writes:
I just wanted to extend my condolences to the TWiP family, Dickson was a titan of humanism and knowledge and will be dearly missed.
In addition to the priceless TWiP archives, he will live on in my Tropical Medicine lessons, as you may see in the photo below (Norway, circa 2023).
Worm regards,
Jason
Seattle
