Manon writes:
Dear Vincent Racaniello, Dickson Despommier, Daniel Griffin, and Christina Naula,
On this sunny afternoon, with unseasonably high temperatures of 28°C, we—a group of medical microbiology residents from Nijmegen, the Netherlands—would like to share our thoughts and response to the latest TWiP case.
For the differential diagnosis of macroscopic worms observed in stool, we considered the following possibilities: Enterobius vermicularis, Taenia solium or T. saginata proglottids (which can be mistaken for worms), Ascaris lumbricoides or A. suum, Anisakiasis (where humans can serve as accidental hosts, although it usually presents differently), or possibly an artefact.
Given the mild symptoms, unremarkable blood work, the size and shape of the worms (~1 cm), and the epidemiological context, we consider an Enterobius vermicularis infection to be the most likely diagnosis. The fact that the feces microscopy comes back negative is not remarkable, as a cellophane tape test is the diagnostic standard. Ova of the Enterobius vermicularis worms are deposited at night in the perianal region. Usually this comes with nightly itch, a symptom the patient however denies. Alongside personal hygiene measures, treatment should be considered for symptomatic patients, which consists of administering a 100 mg dose of mebendazole on days 0 and 14.
Thank you for your case, which gave us a nice starting point for our teaching session on fecal parasites.
On behalf of the Nijmegen Medical Microbiology residents,
Best regards,
Manon Alkema
M. (Manon) Alkema, MD
Resident Medical Microbiology
Clinical Researcher, PhD-candidate
Medical Microbiology – Radboudumc Centre for Infectious Diseases
Radboud university medical center
Nijmegen, The Netherlands
Rafid writes:
Hello Twippers,
Greetings from Quebec. I believe that the most likely diagnosis of the young woman who passed 1cm worms after returning from mexico is infection with enterbios likely acquired before she left for her trip. Perhaps her job has her in contact with young children maybe ?
I would also like to make a quick comment about last months case. Dickson was wondering how Lyme disease ended up in the islands around Nantucket. I was under the impression that ticks often hitch a ride on migratory birds and this is the explanation why Lyme disease is spreading so quickly northward in Quebec. This is something I teach the GPs when I give them little disease refresher talks. Please correct me if I am wrong so that I can improve my lectures.
Cheers and thanks for your good work.
Rafid
Charlie writes:
Greetings to the Amazing Erudites of TWiP,
Long time listener, first time writer from California offering my amateur guess to the case of the young woman who, when having returned from a trip to Mexico, noticed “small white roundworms” moving in her stool.
After reading through some NIH papers and consulting good old Dr. Google, I was fairly confident to diagnose Taenia saginata, commonly known as the beef tapeworm, which she would have acquired much earlier than her Mexico trip if it was already noticeably shedding proglottids. The description of the motile specimens in her stool matches the morphology of proglottids that this intestinal parasite sheds (around 6 per day for mature adults). The fact that she had no itchiness nor rectal discomfort (just abdominal) rules out pinworm, and also pinworm looks more like long threads than round objects. It seems that she is clinically defined as “asymptomatic”.
The only problem with this guess is that Dr. Griffin specifically says the O & P test came back negative, which specifically tests for tapeworms in a stool sample. Perhaps more tests are needed to confirm this result, but just maybe the sample of her stool that was tested did not contain any proglottids. A PCR test could be another way to confirm T. saginata. If her diagnosis is confirmed, a treatment of praziquantel (Biltricide) or niclosamide (Niclocide) would be started, although only Biltricide is approved for use in the United States.
As a current graduate student in computational biochemistry, I find that this is the absolute best scientific podcast out there (MicrobeTV as a whole), in terms of its rigor, depth of analysis, and expertise of the members. It is such a treat to hear such hard science being offered! Thank you so much for your contributions! Wishing all of you only the best in life.
From an adoring fan,
Charlie
Felix writes:
Dear hosts,
I am writing to you from the sunny French Atlantic coast! This case was not easy for me. The absence of anal itching led me to believe that a pinworm infection is unlikely, as that’s normally the main symptom. The symptoms described seem quite mild, so anisakiasis also seems less probable. The most likely diagnosis, to my knowledge, is taeniasis with the passing of proglottids. I’m not entirely sure how this patient would have contracted the infection, but that’s my best guess. Repeated stool exams and serologic testing could provide clarification.
Greetings,
Felix
John writes:
Still hoping to win the textbook
Hello, esteemed hosts. I am still very much a newbie with this being my fourth guess and I hope I didn’t miss something obvious, but I also feel confident this is similar to TWiP 87 “Stumped by Pinworm” where that person also reported abdominal discomfort and no anal itching.
Enterobius vermicularis, commonly known as pinworm, isn’t known for causing disease and can be treated with medications and hygiene. Sometimes, these nematodes can show up in stool and be motile, small white round worms, around the length reported.
Since the life cycle is measured in weeks, it appears the trip to Mexico is a red herring and that would explain Dr. Griffin telling Dickson to not say too much when Dickson said, “I wouldn’t blame it on Mexico.” I’m glad to report I had come to my conclusion before that comment, as it was the final item I wrote down in my list of notes.
If she hadn’t refused a rectal exam, I imagine the scotch tape test would have confirmed diagnosis and since the eggs are not laid inside the GI tract but outside on the perianal area which is why itching is often associated, it makes sense that ova parasite test came back negative, although it is good to rule out co-infections too in the case of pinworm.
Treatment can be expensive, but Pyrantel is a comparably cheap OTC medicine that can save hundreds of dollars on its alternatives, and if taken a second dose two weeks later approaches 100% efficacy due to the multiweek life cycle of pinworm.
I wouldn’t be surprised if we found out the patient works with children since youths have the highest prevalence of infection, and she should pair her treatment with vigilance in hygiene to avoid reinfection.
—
John
Hazel writes:
Greetings Twippos; I hope you’re keeping well. I am writing again from Fake London, where it is an overcast and muggy 25 C, but feels like 33. Before I get to my case guess I wanted to share the cool new trichinella tattoo I got this summer! I hope Dickson especially will appreciate it. 😉
On to the case of the woman from Mexico! After consulting the PD7 pdf, my guess is good old Enterobius vermicularis, the pinworm.
I started my process of elimination by looking for white roundworms of the correct size (approx 1cm), and that narrowed it down to hookworms or pinworms.Both can be symptomless, but hookworm would not be present in stool, as they live in the small intestine. Hookworm eggs would also likely have shown up on the O&P as they are plentiful in stool; and lastly, neither anemia nor eosinophilia were noted in the blood test. Hookworm is voted off the island.
Pinworm infection is also often (even usually) asymptomatic, so lack of itching, cramps, etc. do not rule it out. O&P tests will not detect pinworm Neither does it cause any eosinophilia, or anything else that would show up on a blood test, as far as I can tell. And while it is uncommon, a heavy worm burden can result in adults being seen on the stool. I think we have a winner. PD7 tells me it typically takes 5 weeks from infection to egg laying, so I believe that the woman’s trip to Mexico is entirely unrelated. I’m going to go out on a limb and guess she works with young kids in some capacity, and was infected well before her trip.
As she is living in the US, treatment would be with Pyrantel, repeated after 2-3 weeks to catch any stragglers hatched after the first round. I’d also recommend washing sheets, blankets, towels, etc. in hot water, and drying on blast furnace setting.
Thanks again for all you folks do,
Hazel
PS. It’s my birthday on Saturday (August 31) and a copy of Parasitic Diseases 7 would be a great present, just saying. 😉
Jay writes:
Dear TWiPozoites,
I’ll start with a quotation. “Listen to your patient. He is telling you the diagnosis.” That was William Osler, a leader of 19th-century medical education and purportedly the first North American physician to bring medical students out from the lecture hall and over to patient’s besides for clinical training.
This patient, a woman in her 20s, saw motile white worms, about 1 centimeter in length, in her stool shortly after returning from a week-long trip to a luxury resort in Mexico. She had no other significant symptoms. The day after seeing these worms she presented to an urgent care. Stool O&P exam was ordered, and those results were negative. As I was listening to the case description, I was asking questions in my head such as, “What does she do for a living?”, and, “Does she live alone or with other people?” The TWiP team began asking those same questions.
Then Dixon made a comment, “I wouldn’t blame that one on Mexico.”
Dixon, you took the words out of my mouth. Motile, one centimeter-long, white worms visible on stool strongly suggest Enterobius vermicularis. It takes 4 – 6 eeks from ingestion of eggs to the time the roughly 1 centimeter-long female worms exit the anus to lay eggs on the perianal skin. Occasionally some of these worms end up in the stool. Given this 4 – 6 week maturation time, this woman acquired her pinworm infection before she went to Mexico.
I’ll end with a twist on Osler’s quotation. “Listen to Dixon. He is telling you the diagnosis.” Thank you for the hint Dixon, and thanks as always to the rest of the TWiPozoites for your education and entertainment.
Jay
PS: I’m not sure what to call all of you. Last month one listener wrote TWiPozoities, and I love that. What would you prefer? Perhaps you should take nominations and put it to a vote. I nominate TWiPanosomes.
Jay Gladstein, M.D. | Chief Medical Officer
APLA Health & Wellness
Olympic Medical Clinic
Frithjof (Freed-Yoff) writes:
Hello dear TWIPsters,
Greetings from Hannover, Germany. It’s always nice to think about something captivating like your monthly enigmas, when you really should be studying for your finals. The woman in her 20ies returning from Mexico has a pinworm-infection, I would say. Enterobius vermicularis can be detected with an adhesive tape test. This parasite is extremely common, here in Germany and probably also in the US. So the infection in this case is not necessarily connected to the vacation but maybe to an exposition at home or at her workplace. Talking of which, it seems like the real question here is what she does for a living. I would guess she works with children, maybe in a kindergarten or daycare. You should also reveal this second mystery!
Yours Frithjof (Freed-Yoff)
Rod writes:
Hi all at TWiP,
I have been enjoying TWiP for the past few years. I am a retired science teacher and studied parasitology as part of a degree in biology back in the 1980s at North East London Polytechnic.
Having recently listened to all the early episodes of TWiP in order to brush up my parasitological knowledge I suspect that the lady in question with small, white, motile worms in her stool has a pinworm infection- Enterobous vermicularis, (episode #19). Her doctor therefore should treat her with Mebendazole, or similar antihelminthic medications. Other members of her household may also require treatment as this is an infectious condition.
Thanks again for keeping us informed, educated and entertained.
Warmest regards from North Portugal.
Rod
Justin writes:
Dear twip hosts,
For the case of a young woman with small round worms and no other symptoms my first thought is pinworms. They are about the right size and very common. They can be asymptomatic but often cause anal itching. If it is pinworms it would have taken several weeks for worms to start being present in the stool ruling out an infection while in Mexico. Perhaps the patient works with young children? That might explain the route of exposure.
All the best,
Justin
Håkon writes:
Greetings again from sunny Athens,
For this week’s case, I narrowed it down to two potential options given the lack of worms in hand, the lack of ova seen on stool examination, and the lack of a scotch tape test mentioned. Law of averages says she acquired pinworms from the salad line by an individual who didn’t wash their hands, however it’s also possible she managed to acquire some sort of cestode. In this case I would suggest an infection by Dipyllidium caninum. While there, it’s possible a flea managed to work its way into the salad bar from a stray animal and she ingested it unknowingly, thus giving her the cestode. While much less likely than the pinworm, they are 1cm long “worms” you would not necessarily see ova in the stool for as the proglottids shed independently. I find it much more likely she contracted enterobius vermicularis while abroad, either through aerosolization, from handling infected currency, or from someone who inoculated the salad spoon after a trip to the bathroom. Scotch tape test might help confirm.
Thanks for another fun case,
Håkon
RITA writes:
Enterobiasis (Pin Worms)!
The young woman’s recent vacation in Mexico may be a red herring.
There are plenty of pin worms to go around here in the USA.
Pin worm ova escape detection in the feces, because the worm deposits her eggs on the external perianal area of the host.
This itches like the blue blazes. I know this because I have been a sufferer of Enterobiasis, myself.
I’m surprised that the patient did not describe itching symptoms, because it’s pretty darned hard to ignore. Was she perhaps too shy to mention it?
Pin worm ova are spread by the host scratching “down there”, and spreading ova by unwashed hands.
The unfortunate host may have ingested food prepared with insufficiently washed hands. ( Use a brush to get under those nails)
It’s remotely possible to contract during sexual intimacy.
Pin worms are more common in children, but I’m here to tell ya, young adults can also be infected.
I’m writing from beautiful Owyhee county, Idaho where it’s sunny and a comfortable 80f.
Thank you for the discussion on Babesiosis. I lost my good working sheepdog a couple of years ago, to hemolytic anemia, that I suspect was caused by babesiosis, acquired in the tick-abundant places where we work.
I’ve become a staunch believer in tick control products for my dogs.
Thank you for informative, and fun ( for me) shows and podcasts.
RITA
Jerod writes:
I am sure this one will be solved quickly so I will write now before bed:
This is the same sort of parasite in many cats.
My guess is roundworms and I cannot guess the occupation of the woman involved because this is far too common.
(Sadly I am between jobs at the moment so I too am a parasite.)
-Jerod
David writes:
Greetings,
I hope this email finds you all well and enjoying the remaining days of summer.
The case of the 1cm long white worms in stool reported by the traveler returning from Mexico seems likely to be a case of pinworms. While the stool O+P comes back negative, it may be that the infection is not severe enough to be detected yet. I considered tapeworms as a possible source, but that seems unlikely given both their rarity, and more importantly, the reported 1cm size of the worms seen.
Perhaps the young woman was exposed to pinworm eggs prior to the trip to Mexico, and the worms thrived and enjoyed the vacation as much as she did!
Very curious as to the source of the exposure, and looking forward to hearing the rest of the story.
Thanks as always for another informative and entertaining episode.
David in Maryland
John writes:
TWIPer’s,
Thanks for another great episode!
I have a suggestion for a parasite hero. I don’t think she has been featured before so please ignore if this is a repeat.
Dr. Mary Pritchard worked at UNL’s Manter lab of Parasitology and they recently celebrated her 100th birthday with a series of talks:
https://hwml.unl.edu/documents/centenary
peace
John Shea, SJ, Ph.D.
Associate Professor of Biology
Creighton University
Wayne writes:
Dear Dr. Griffin,
It is not very often I disagree with what you and the other experts say in the various TWIX podcasts. Most of the time I fully agree with the specialty crews, especially in the use of correct terminology such DNA mutations vs. amino acids changes in proteins; one of my pet peeves is diseases are not transmitted – pathogens are.
However, this week I feel as though I have to correct you. In your discussion in the TWIP 241 podcast (51:09) on Babesiosis you indicated that a tick can ‘jump’ from a piece of grass on to a host. I have worked with ticks for the past 25 years and have yet to see one jump. They will wait until you brush against the foliage on which they are waiting, then grab hold of you – they do not jump on to you.
That said, there was an interesting paper that came out last year that could suggest a jump: Static electricity passively attracts ticks onto hosts. https://doi.org/10.1016/j.cub.2023.06.021
- Their summary
- Static charges of animals result in strong electric fields when close to vegetation
- Ticks are pulled by these electric fields across air gaps of several body lengths
- This likely increases the host-seeking efficiency of ticks and other ectoparasites
- Electrostatic attraction of ticks is independent of the host’s charge polarity
As usual, another interesting podcast.
Wayne Hynes, Ph.D.
Professor, Department of Biological Sciences
Old Dominion University
Daniel agrees! https://www.nationalgeographic.com/animals/article/flying-ticks-static-electricity-diseases