Marcus writes:

Hi TWiP,

I’m writing from the University of Washington, Seattle, after recently hearing about this podcast from my professor Dr. Drew Bell in my MICROM460 class. Although we haven’t covered helminths extensively in class yet, I still thought I would take a stab at this week’s case. I believe the parasitic worm described in the provided case is Ascaris lumbricoides.

Given the unsegmented nature of the worm as well as the description of being pointy on one end, but not the other, I began by narrowing my identification down to the nematodes. The large size of the worm eliminated my suspicion of pinworms or hookworms, and the lack of more severe symptoms beyond abdominal discomfort, bloating, and nausea indicated the possibility of ascariasis. This aligns with the pharmacist’s recommendation of mebendazole, as well as the patient’s location in India.

I really enjoyed listening to this week’s episode, and I’m looking forward to the reveal in the next one.

Best regards,


Charles writes:


We are the parasitology geeks from McGill Campus Outaouais (First-year medical students).

Our answer is Ascaris Lumbricoides for the clinical case from the podcast on april 19th.

Hope we win!

Charles Gervais, B.Sc (Hons)

Étudiant de première année en médecine/MED-1 Student

Rodolfo writes:
Dear TWiPers,

Greetings from Brazil!

The patient in question is very likely infected by Ascaris lumbricoides. Three facts must be taken into account here: the symptomatology, with a persistent abdominal discomfort, along with nausea and bloating, which, nonspecific as it is, could be caused by a parasitic disease; the use of mebendazole, an antihelmintic broad-spectrum drug, but mainly used to treat nematode infections; the vomited worm and its morphology, that leads us to think about a macroscopic parasite, and to discard cestodes and flukes. Among the nematodes the mebendazole treats, the biggest in size is the Ascaris, and the description given leads me to believe it is a male. Though they live in the duodenum of their hosts, these worms can be regurgitated during an emetic episode, and a bolus of adults might explain the abdominal discomfort, and an old paper (from 1917, to be precise) showed that Ascaris suum can survive more than 10 days outside the host’s body. Our patient should seek medical help, as killing the worms of a possible bolus could worsen his clinical condition and even lead to an intestinal obstruction.

To confirm this diagnostic hypothesis, an abdominal physical examination is in order, to seek any abnormal masses, signs of peritonitis or organ-specific affections, and ascites. Also, one should ask for a stool examination, and an ultrasound of the pancreatic and biliary ducts in order to investigate eventual hepatobiliary ascariasis – if this diagnosis is confirmed or not discarded, an ERCP could be performed.

Thank you very much for this great program!

Rodolfo Ventura Oliveira

Estudante de Medicina – FM

Universidade de Brasília

Krysta writes:
Hi TWIP hosts,

I just finished listening to this episode while getting ready for work; I often listen on my commute to campus. I did a quick search for mebendazole, and the first result was pinworms! However, the size of the worm doesn’t fit that, and the symptoms weren’t well aligned either. MayoClinic says this can also be used to treat whipworms, hookworms, and Ascaris lumbricoides. A quick search confirmed that the size and symptoms of A. lumbricoides fit, and that is an extremely common infection in many parts of the world including India, so that’s my guess.

I teach intro microbiology, and I’m planning to incorporate more case studies next semester- TWIP is such an excellent source, thanks for providing these!

All the best,

Krysta Bready

Pima Community College, Tucson, AZ

Tuomas writes:

7 inches – that’s an angry giant intestinal worm!

Jay writes:

Dear TWiPsters, 

I’m loving your podcast. I also have fun writing in which I began doing a few months ago. I’m a bit self-conscious of the perhaps excessive length of my recent submissions. So in an attempt to keep this one brief, I wrote a haiku. 

Medendazole roused

The nematode from its lair

The suff’ring host hurls

Perhaps this haiku would have been appreciated by Shimesu Koino who intentionally infected himself and his younger brother with Ascaris suum and Ascaris lumbricoides in the 1920s. I suspect this man had Ascaris lumbricoides which is very common in India. The prevalence there is estimated to be close to 20% of the population or about 150 million people. 

Keep hurling out your great work!


Jay Gladstein, M.D. | Chief Medical Officer

APLA Health & Wellness

Olympic Medical Clinic | Los Angeles, CA

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

Dear Lumbri-cuties,

The case presentation, or rather, the size and shape of the worm, is typical for ascariasis. Just this week we received a patient from the surgical department with inflammation of the gallbladder and a large number of worms visible in the gallbladder on MRI and ultrasound. While the morphology was also typical for ascariasis, the surgeons doubted the diagnosis because the patient had been living in Austria for 30+ years and denied traveling outside of Europe.

Of course, Sherlock Holmes teaches us that eliminating the impossible and leaving the improbable must lead us to truth, it is obvious that there is a bias at work here. Ascariasis is prevalent in many countries in eastern and southern Europe, but parasitic infections are often seen as diseases of poverty, of underdevelopment, of uncleanliness. In contrast, Europe as a continent is contrasted with the “global south”, despite the fact that poverty is prevalent and rising everywhere. 

We strongly recommend the article “Europe’s neglected infections of poverty” by Peter Hotez and Meredith Gurwith, which is open access and can be found here: 

Thank you for this great case. All the best, 

Michelle and Alexander from the First Vienna Parasitology Passion Club

Eyal writes:

Dear Vincent, Dickson, Daniel, and Christina,

Greetings from Sydney and the land down under.

I hope this guess arrives in time. Sometimes the podcast episode arrives late on the apple podcast app, leaving only a few days to submit a guess. However, this time I decided to take the chance and wait for a certain 7th edition of a certain large red book to arrive so I can be more certain about my guess.

(Vincent, thank you so much, the book has finally made the journey :))

As for the man in his 50s. Hearing about a large abdominal non-segmented worm my gut reaction (pun intended :)) was Ascaris.

After reading through the nematode section I’m fairly confident that the man is infected by a large number of Ascaris Lumbricoides.

In my mind all of Ascaris’s properties match the case:

Ascaris is extremely prevalent in India, 

size matches being the largest nematode infecting humans, with adult worms reaching between 15 and 30 centimeters

generalized abdominal symptoms match as well, indicating something causing obstructions in the gut.

Shape matches as well, with one end being pointy and the other I’m assuming tapers into a twirl?

Finally, mebendazol is available over the counter. being a treatment for Ascaris it’s an additional piece of evidence in favour of Ascaris.

As always, I’m grateful for the knowledge and perspective you share.

Best regards,


Rafid writes:


Please forgive the brief answer but I have been on call a lot lately and it has been very busy so I will keep it short. Ascarias. That is my final answer. Cheers and thank you again for your excellent podcast.


Byron writes:
Good afternoon TWIP Drs,

Writing from a rainy afternoon in Illinois. We had a stretch of great weather for spring and now back to the normal April showers. Not a lot of information for this case, I sense the treatment of mebendazole could be a hint so looked up PD Version with infection treatment of mebendazole. Received 7 entries, cross check those entries with worm size and life cycle, found Ascaris Lumbricoides offers the best match. Other parasites either are too small or do not involve a migration stage where they can be coughed up. I think this would be my guess. Waiting for the next case and hope this email is not too late. 

P.S. Thank you so much for mailing the book! I think I mentioned in my previous email that I often listened to the podcast while driving my son to his violin practice. So when I showed him the book, to my surprise, he immediately said, “Is this the book from the podcast by Vincent Racaniello that you listened?” . Good for him paying attention, I had thought he was asleep most of the time. 🙂 Thank you again for the book, this is priceless. 


Felix writes:

Dear hosts,

I have to keep this one really short since I am busy on vacation relaxing at the pool. Ascaris lumbricoides seems to check all the boxes in this one.

I am looking forward to some interesting differentials.



Christian writes:

Dear Twip Team

Greetings from a surprisingly cold Basel.

The description of this worm sounds very much like Ascaris lumbricoides, as not many non-segmented helminths grow to this size. 

Mebendazole would be toxic to the worm, so it is possible that it tried to flee the now toxic environment of the small bowl, where it usually resides.

Similar events have been reported from people being put under anesthesia (I do not recommend to google these pictures…).

It is also famous for causing anemia in heavily infested people and even bowel obstruction in extreme cases.

The infection usually occurs by ingesting fertilized eggs from contaminated food sources and although the eggs are very hardy, the worm itself is not, with usually

a single dose of albendazol or ivermectin being enough to kill it.

In this case it is possible that the over-the-counter dose of mebendazol was not high enough, hence the worm exited the unfavourable host.

All the best, looking forward to the next case.


Justin writes:

Hello all,

After looking online for “India Worm Vomiting” I discovered an article from the Times of India about a viral video of a worm vomited up after a patient took Vermox (mebendazole). The AI-generated photo the article used shows a segmented worm, but the video clearly shows a large unsegmented worm in a sink. After a brief further search, I will make a guess of Ascaris lumbricoides (roundworm) as India is estimated to have 20-25% of all cases worldwide.

All the best,


Alex writes:

Dear TWiP Professors,

Hola from the Camino del Norte in Northern Spain! I am currently in the small coastal town of Luarca, where it is a sunny 15 degrees Celsius with a light breeze — surprisingly similar to the conditions in my hometown of Calgary, Canada where it apparently snowed 12 cm just last week. I have been listening to TWiP on and off for the past few years through my undergraduate microbiology degree, and having some free time while walking has allowed me to finally catch up enough to write in with a guess. 

Firstly, I want to join the long line of people thanking you for all your efforts in science education. I am deeply grateful for the invaluable information and passion you share so generously and have in fact been inspired by this podcast and TWiV to apply for a research Master’s in Europe in the field of infectious disease. Since finishing my undergrad degree in 2023 I have been longing to contribute to the study of parasitic diseases, and I am hoping to eventually follow in Dr. Griffin’s footsteps of infectious disease medicine. I would simply not have discovered or been as passionate about the amazing world of parasites without the combination of your welcoming, patient attitudes towards new learners and vast knowledge in your respective fields. I along with many others truly owe a great debt to all of you!

I fear I may have already overstayed my welcome in my very first email, so I will resist my long-winded nature and keep it short for my guess: I believe this is an infection of Ascaris lumbricoides, indicated by the large nonsegmented worm, symptoms, and mebendazole treatment. 

Best wishes,


Corey writes:


Greetings from OU’s parasitology class. Today was a slightly windy and sunny day with the temperatures hitting 80. This week in our class we listened to episode 233 of the podcast. As a class, we conclude that the 50 y.o. male complaining of stomach pains and nausea was infected with the parasitic hookworm Ascariasis. This is due to the area this case was in (India), the lack of segmentation in the worm, how long the worm was, and presented the same symptoms that an Ascariasis infection would give. 

Thank you, 

























Dr. Aysha Prather 

Courtney writes:

Hello TWIP team!

My name is Courtney. I am an undergrad at California State University Dominguez Hills, majoring in Clinical Laboratory Sciences and minoring in Microbiology. Since switching from nursing to the laboratory, I have listened to the ASM podcasts for the last five years. I work the graveyard shift as a laboratory technician while in school, and your podcasts make the night go by quickly while streaking on agar or processing virology.

I have a niche passion for microbiology, specifically parasitology, and the case studies you presented will send me down the rabbit hole of textbooks and online searches as I try to confirm the answer. I hope I’m not too late to present my answer to last week’s case study.

For the following case study of a 50-year-old male presenting to the pharmacy with symptoms of abdominal discomfort, nausea, and bloating, later given Mebendazole.

Mebendazole can treat parasitic infections such as Ascariasis, Pinworms, Hookworms, Hydatid disease, and Giardia. 

However, the patient vomited a nonsegmented worm, so Giardia is out. Hydatid disease, or Echinococcosis, is a parasitic infection caused by tapeworm, a segmented worm, which is also out. 

Hookworms can travel to the gut from stepping on infected soil, but their total size can be 8-15mm, depending on the worm’s sex. These worms can travel to the lungs, mature, and be reingested where living in the gut is probable. Similarly, pinworms are transmitted through the fecal-oral route and primarily live in the large intestine. Their size is roughly 6-13mm long. Both of these worms are too small; when the case mentions the worm size was roughly 7 inches. 

This only leaves one left, and it’s Ascarias. This parasite’s structure fits the description of pointy at one end and the worm’s length. This parasite’s life cycle includes the individual consuming the eggs through unwashed fruits and veggies of contaminated soil. The eggs will hatch in the small intestine and travel to the lungs and heart through the bloodstream or lymph fluid. After maturing in the lungs for 10-14 days, they break into the airway, travel up the throat, coughed up, and reingested. Back in the gut, they mature and grow up to 40cm or 11 inches. The females reproduce in the gut, and the whole cycle of egg ingestion to egg deposit is 2-3 months, and the adult worms can live in the gut for a year or two. 

This parasite is highly prevalent in India, where the patient is located. Based on how many worms the infected patient has in their gut contributes to their symptoms of abdominal pain, bloating, and nausea. 

The laboratory I work for used to identify worms and other gut parasites a few years before I started working there. We no longer do that; many specimens are preserved in jars to teach our CLS interns. Often, when it is a slow night, I like to bust out the old slides, teach myself what to look for, and practice the identification of oocytes or cysts. 

Thank you for all that you do and the education you provide. As we say in the lab, “Ooooo parasites, fun to look at, not to have!”

– Courtney

(an aspiring parasitologist)  

Stefan writes:
Dear TWIP team,

greetings from cloudy/rainy/haily/sunnyHeidelberg with with typical changing April weather and 6 degrees Celsius.

The case description on morphology (no segments, size) would be in line with Ascraris lumbricoides and “teasing” the worm out (or scaring it away?) with mebendazole out of the intestines via the oral end is a rare but reported event, as is ectopic location in the bile duct.

Mebendazole would be the treatment of choice and repeated treatment for multiple infection may be considered.

Hope I’m in time this time with my response. Thanks for all your great work,



Jason writes:

Greetings TWiP hosts!

I am writing to you from Kabale, Uganda where it is 22 degrees C and raining, and with intermittent power outages. Since I last wrote in to TWiP I have received a Master’s degree in Infectious Diseases from LSHTM, and have just embarked upon the PhD in Health Professions Education program at Widener University in Pennsylvania. Your various podcast offerings continue to fuel my academic studies and I can’t thank you enough for all of your efforts.

In the TWiP 233 Case of the Regurgitated Wriggler, the history is highly suggestive of infection with Ascaris lumbricoides, also known as the giant intestinal roundworm. Oral expulsion of a 7-inch nematode following the administration of mebendazole is virtually pathognomonic for ascariasis.

Worm regards,



I have included two photos taken today at Uganda’s Lake Bunyonyi with Dr. Despommier in mind. I recall from earlier episodes that he is an avid fisherman, and the crayfish and catfish shown here is offered as tribute to his Louisiana origins.

Håkon writes:

Hello again from balmy Athens- this week’s case of a large “approximately 7 inch long worm” in a man from India made me think of Ascaris lumbricoides. While I’m familiar with other large nematodes that infect people ( D. renale, D. medinensis, etc), none of these are typically treated with mebendazole nor as ubiquitous as A. lumbricoides- especially in India. Without the worm in hand to look at, the law of averages is my muse. Thanks again for another episode.


Carol writes:

I believe this is Anisakiasis


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