Anthony writes:

Visceral Larva Migrans Associated With Earthworm Ingestion: Clinical Evolution in an Adolescent Patient

After Dr. Despommier mentioned earthworms as a mechanical vector of Baylisascaris, I looked to see if I could find more on Google.  I didn’t come across anything specific to that, but I did find this report of a human infection of Toxocara (canis?) infection via earthworm.  

So, it would seem likely that earthworms could carry the embryonated Baylisascaris eggs not only to rodents but also to insectivores and to birds eating worms.  These might not be attracted to the partially digested grain in the raccoon latrines. Earthworms could be not only increasing the physical space infected by Baylisascaris, but also the species space of hosts.


Hetty writes:

Three year old boy, in tropical S. America, Stool O&P sent out, contained something that gave diagnosis.

Send your case diagnosis, questions and comments.

My diagnosis is Ascariasis.

30 years ago my boyfriend at that time did part of his internship in Brazil, where he investigated childrens stools, the mothers would bring him their childrens stool in exchange for anti-helminthics. He looked for eggs with the microscope. After treatment the mums brought him the worms that came out too, and got the second dose.

He did this in 3 environments; rich, middle and poor. He did measure the number of worms plus some characteristics of the children; weight, skin thickness etc.

He kept sending me (real!) long letters with photo’s of piles of yellow-brownish worms.

Good old times.

Hetty Koppenaal

Public health doctor

Infectious diseases & STD dpt

Municipal Health Services

The Netherlands

Peter writes:

A cháirde TWIP,

Daniel was wondering about people in Ireland speaking Irish vs Gaelic. To me they are both the same thing. In Ireland we call our language Irish (or Gaeilge if speaking Irish) and outside Ireland people tend to call it Gaelic. Some might say Gaelic is more associated with Scotland, but just as you can say Scot’s Gaelic you can also say Irish Gaelic. To bring it back to parasitology the Irish potatoe famine would have been one of the factors in the demise of the Irish language, with a disproportionate amount of Irish speakers living in poverty at the time, resulting in higher death rates and emigration amongst them. Fionn Ó Marcaigh in our department, who works on evolutionary divergence, is also a great advocate for the Irish language. I asked him about the Irish revival Daniel encountered last summer. He told me it is true, in Dublin in particular, there have been new movements such as “Pop up Gaeltacht”, where people meet to speak Irish in pubs and the twitter account @theirishfor is becoming very popular. So the language is being used by new people in new ways. Unfortunately there has been a decline in Irish speakers in traditional Irish speaking areas (Gaeltachts). Fionn pointed me towards quite a good piece in the Irish Times discussing this.

Fionn recently also wrote a great blog on Irish animal names and linguistic relativity, “the relationship between the language a person speaks and the way that person thinks and views the world” ( My favourite, the Irish for jellyfish translates as seal snot. Again to bring it back to parasitology Fionn tweeted on Valentine’s Day that the Irish word “Gaolín” can mean sweetheart or alternatively a parasite, literal meaning little relative. I think that tells you a lot about the Irish mind!

Onto the case study. As with the last episode I asked for help and this time all the parasitology postgrads rallied to my call. So as well as Gwen and Maureen mentioned in my last email, I was joined by Rachel Byrne and Paula Tierney. Rachel currently works on the parasites of the Eurasian badger, an important study due to badgers association with bovine TB, with little known of their parasites let alone how they may interact with TB infections or the planned badger TB vaccination. Paula and Dickson could probably spend a good afternoon picking each other’s brains on a riverbank, given Paula currently works on helminth parasite communities of common dace (Leuciscus leuciscus), an invasive freshwater fish in Ireland and brown trout (Salmo trutta), an economically important native sympatric species.

The case study symptoms were not as obvious to us as the Leishmania case, with the dirt floor allowing everybody to suggest their favourite parasite as a candidate, Ascaris or hookworms maybe. To narrow it down we searched Parasitic Diseases for constipation, which we thought an unusual symptom as parasitic diseases are normally more associated with diarrhoea. Constipation was only associated with Chagas disease and strongyloidiasis. As the faecal examination was key, as opposed to a blood test, we ruled out Chagas. We first thought it was Strongyoides fuelleborni due to swollen belly syndrome, but then realised it was limited to Papua New Guinea and Sub-Saharan Africa. This left our diagnosis as Strongyloides stercoralis, with infection coming from the soil, possibly contaminated by visiting animals, most likely the dogs or possibly asymptomatic family members. The abdominal distension is a syndrome that can develop with S. stercoralis in children as is the anorexia and cachexia observed. We found the increase in pain throughout the day interesting, but believe this may be due to pain when eating. The child is malnourished which appears to have led to a hyper infection. This could explain the toxic appearance of the child and secondary infection by micro-organisms making him febrile. We thought the anal rash could have been as a result of the worms entering when the child was sitting rather than through the foot, but reading it stated “Recurrent rashes are known as larva currens or creeping infection. It occurs from strongyloides autoinfection and appears as an eruption beginning in the perianal region”. Autoinfection would also explain the coughing. The breakdown of skin around the mouth and dark urine threw me off a bit and I thought perhaps there was a co-infecting parasite. Some searching suggested dark urine is not only caused by blood in the urine, which was my first thought, but also dehydration, which also explains the breakdown around the mouth. Some reading of the literature revealed dehydration associated with some severe cases of strongyloidiasis. So yes it seems to be Strongyoides fuelleborni. Diagnosis by examination of as much stool as possible using sedimentation. Further testing by ELISA due to the evidence of hyperinfection. Prolonged treatment with ivermectin and albendozole. Supportive therapy if hyperinfection confirmed as well as treatment to treat dehydration and malnourishment. Very sad case but helps highlight the great and I am sure too often unacknowledged work Dr. Griffin and his colleagues carry out. Thank you.

I am conscious this is already a long email and last week you got 15 case study emails, but listening to you talk about Theodor Bilharz I thought you would enjoy this story. In 2002, I watched a surfing documentary about some of the first American surfers to travel the world in search of the perfect wave. I believe it was in Africa where they used to travel by commercial riverboat and then paddle on their surfboards downriver to find the shore and hopefully some sweet breaks. Just as Daniel said, the local people are well informed and used to shout BILHARZIA, BILHARZIA at them in warning as they paddled past. These laid back surfers just thought cool, some guy call Bill Harzy must have surfed here before and kept on paddling! As far as I recall none of them got infected though.

Finally it being TWIP I have to mention “The beast from the East”, the forecasted weather due to hit Ireland with one of the coldest weeks in 3 decades!


Peter Stuart,

Trinity College Dublin

(PS Rachel being very good at Science Communication and suggested I add our groups twitter handle to my signature, she’s right! @TCDParasitology)

Arthur writes:

Hello Twipanosome trio

My name is Arthur and I am an undergrad student in CT studying infectious diseases and how they influence our species’ evolution and culture. I found TWiP through a recent mention on NPR and love it as well as the whole brand of This Week in blank.

I’m emailing you as a layman, but I have a guess for the case study in episode 147 of a three year old with perianal skin inflammation, distended belly, pellet-like stool and low weight. My guess, which is likely wrong given the odds, is a rare symptomatic infection with Diplydium caninum, the flea tapeworm. Diagnosis of this would be through identifying proglottids in the feces. There are two reasons I can think of that the older children are not symptomatic. Firstly, older children tend to behave differently around dogs and are unlikely to ingest a flea [the requirement for transmitting the disease] or

they are simply larger and would require a higher ‘dose’ of parasites to become symptomatic.

Either way, I worry I am likely wrong because the total amount of recorded symptomatic cases is somewhere in the low dozens, though that doesn’t discourage me from hazarding this guess. Thank you very much for the podcasts that occupy my nearly hour long commute.


PS: Do any of you have recommended reading that covers the parallel evolution of parasites and humans? Or any that might detail changes in cultures on account of specific diseases? Thank you again.

Andrew writes:

Hello TWiP-tologists!

I submitted an answer a few cases ago, but I was late submitting so it ended up getting read the next time around… so I’m not going to let that happen again! I wanted to submit an answer to TWiP case number 147 and hopefully win one of your fantastic (SIGNED!!!!) books. This one’s about the three year old boy from South America. As I said in my last response, I am the guy who sits at the microscope and diagnoses these organisms every day for physicians- think: a much younger Dickson Despommier! I consulted my Medical Director on this one, since it relies so heavily on the clinical presentation, so here is our combined response:

At first, I immediately thought of Schistosomiasis- probably Schistosoma mansoni. His cough, abdominal pain and febrile presentation could be Katayama fever, and this would also cover the suggestion of hepatobiliary involvement. As for the “scaly skin” around the perianal area and breakdown of skin around the mouth, I thought maybe he was sitting in a pond, while also drinking dirty water. But my medical director pointed out to me that Schistosoma mansoni is usually found in the venules of the large intestine not the small intestine and that the scaly rashes could be sequelae of malnutrition. I think it would be important to ask his mother is he has had any exposure to contaminated water (with snails) lately. I don’t think it is this though… no mention of water, he seems too sick and it seems more like one of my other two options- I would also expect his siblings to be sick if it was from the water, as a three year old would likely not be in the water alone.

Also at the top of our differential diagnosis list are Ascaris lumbricoides and Hookworm. Some longer shots, that don’t seem to fit (but could theoretically be possible) are: Strongyloides stercoralis, Trichuris thrichiura, intestinal Capillariasis, Toxocara, and Hymenolepsis nana.

Hookworm is an option as the dirt floor would be the perfect way to obtain it through the skin and the patient’s location in South America would fit. Hookworm has a lung phase that occurs after the larvae travel through the bloodstream or lymphatic system into lungs. After this, the worms then emerge into the throat and are swallowed and enter the small intestine, thus successfully auto-infecting the patient. High enough numbers of organisms (AKA: worm burden) could cause a distended abdomen, however a distended abdomen could also be from malnourishment and malabsorption, which we know he has from his stunted growth and general edema. Hookworm is very classically related to malnutrition and anemia that this almost wants to scream “Hookworm!!”, however the skin presentation is a curveball here for me. The rash associated with hookworm is usually at the site of penetration, or it can spread due to cutaneous larva migrans… and is very itchy. But, it appears this was not itchy -there was also no mention of spreading. I have read some sources that have said that the rear portions of the lesions can be dry and crusty, but I would still suspect an itchiness. I would ask the mother if she had noticed him itching… I understand the boy is three, so it may be hard to tell. However; in your book, there are a few nods toward the association of hookworm and dogs, which we know were present. Ancylostoma braziliense is associated with cutaneous larva migrans AND the host is dogs, but this doesn’t seem like a typical cutaneous larva migrans to me, and A. braziliense infection doesn’t seem to have a systemic phase to it. My guess here would be Necator americanus, not Ancylostoma.

Ascaris lumbricoides is our other guess. South America is a common place for this helminth as well.  Unlike the hookworm, Ascaris ova will usually be ingested. After ingestion of the Ascaris eggs, they hatch in the small intestine and the larvae migrate through the bloodstream or lymphatic system into the lungs. As they travel through the lungs, they will usually cause some sort of respiratory symptoms such as coughing or wheezing. Your book also states that Ascaris can produce an allergic response that mimics asthma. After spending six to ten days in the lungs, the larvae travel to the throat, where they are coughed up and then swallowed, to effectively auto-infect the patient. The distended abdomen, abdominal pain, constipation, malnutrition, stunted growth, and fever all add up to Ascaris. Ascaris infections can have distended abdomens as the worm burden can be very high- this is also what seems to cause the constipation. The source of Ascaris lumbricoides is soil-borne through hand-to-mouth contact which would make sense for a 3 year old who crawls everywhere and is close to the ground. The one thing that stops me from pulling the trigger on this one is the scaly rash, however as my Medical Director said, it could be a sequelae from malnutrition, and I have also read that there can be allergic reactions to Ascaris lumbricoides that may or may not present this way. It may also be possible he has a co-infection of Ascaris lumbricoides and Trichuris trichiura as these two are commonly found together in infected patients, and he seems too sick for it to JUST be whipworm.

If I were somehow granted a medical degree and given rights to see this patient, these three would be the first three on my differential diagnosis list. The two that are tied for number one are Hookworm infection and Ascariasis, with or without a co-infection of Trichuris. Given what we know, I would lean toward Hookworm, since there are dogs around and he is so malnourished. I would prefer to rely on the stool O&P exam for a definitive diagnosis, and I would give the boy Albendazole in the meantime while the results are pending from the lab, but I’d bet this was Hookworm infection, most likely caused by Necator americanus.

In an O&P exam, if the diagnosis is Ascaris lumbricoides, I would expect to see mamillated, ovoid eggs that are usually brown from being stained with bile and measure about 50-70 microns long under the wet prep or iodine prep exam. Ascaris eggs are very distinguishable from most other helminths. It is also not uncommon to see adult Ascaris worms in the stool/ toilet. Ascaris is known as the “giant roundworm” and that is because adults (usually females) can grow up to a foot long and typically the patient (especially if the abdomen is distended) is infected with many, many, many worms, and yes they are usually alive and moving!! I had an adult Ascaris worm submitted that was still moving when I was a student at my clinical internship and it was about 8 or 9 inches long! They make a really cool show-and-tell when we have lab visitors!

If the diagnosis were hookworm however, I would expect to see eggs that are ovoid with a clear shell and dark embryo on a wet prep or iodine prep exam. Hookworm eggs typically measure about 60-75 microns long and are also pretty distinguishable from other helminth ova. They appear a lot “cleaner” than Ascaris ova on microscopic exam. You would not see larvae or adults in the stool (unless the sample was old and the eggs hatched).

So, that’s my answer – but, I have one question that I was wondering about with this case that maybe you have answered already… You said the belly pain increases through out the day- can you tell me what is causing that?

Sorry this is so long, there’s a lot to consider here. Thank you for your fantastic podcast!

Your friend,

Andrew Berens, MLS(ASCP)

PS: There was some discussion last time regarding the letters after my name. MLS stands for Medical Laboratory Scientist, you got that right! But, ASCP stands for the American Society for Clinical PATHOLOGY, not Parasitology – although I LOVE Parasitology and totally would get that certification if I could. It means I am competent to work in all areas of a clinical lab, not just Microbiology or Parasitology.

David writes:

Dear Hosts,

I believe the 3-year old South American boy has been infected with the soil-transmitted helmith Strongyloides stercoralis. The filariform larvae residing in the contaminated dirt floor penetrated the boy’s skin near his mouth and anus, which explains the breakdown and inflammation of the skin in those regions. Those larvae which migrate to the small intestine have become adults, which result in the boy’s abdominal symptoms (distended belly, aches, constipation), and the remaining symptoms (cough, fever, unresponsiveness) can be attributed to the dissemination of the worms throughout the boy’s body. Typically, S. stercoralis is prevalent in the immunocompromised, but given the poverty the boy lives in, it is feasible he is malnourished and has an underdeveloped immune system.

Thank you once again for the informative and entertaining podcasts.

David P.

Patricio writes:


My name is Patricio Rojas and I live in Ecuador. I work in a private university in Quito and teach an undergrad course of Microbiology. I have been recently following TWiM & TWiP and I am becoming a fan of these wonderful programs.

My suspicion for case 147 is the geohelminth Ascaris lumbricoides which can cause partial or complete gut obstruction plus can migrate to pancreatic and biliary ducts. The diagnosis is performed by the distinctive ova shed on stools and occasionally by the presence of the worms. Other symptoms may arise by the fact that the larval forms have to migrate to lungs in order to maturate. Therefore, patients can present from cough to a pulmonary condition known as Loeffler syndrome. Geohelminth infections are highly prevalent in developing countries, especially in rural and suburban areas. Living without clean water, in direct contact with dirt and mud plus having pets and other domestic animals can increase the risk.

Best regards,

Patricio Rojas M.D., Ph.D.


School of Medical Sciences

Universidad Tecnologica Equinoccial