Dear Professors Twip,
After a longer time of absence in writing, I am finally writing with another case guess.
The presentation of the worms found in the stomach (white, burrowing in the stomach wall) immediately brings to mind Anisakiasis, caused by the nematode Anisakis simplex. These worms that can be acquired through the consumption of raw or undercooked seafood try to borough through the stomach wall, which they are unable to pass, causing pain and a local esosinophilic reaction. Two things, however, do not fit with the suspected diagnosis. First of, the larvae of Anisakis are typically bigger (around 2 centimeter in length). Maybe the case description was referring to 2.8 mm in diameter and not in length? Or maybe it was supposed to mean 2.8 centimeters?
The second obstacle in the diagnosis is the timing. Anisakiasis is typically an acute infection with symptoms occurring only hours after ingestion of the raw fish or seafood. However, there have been rare reports of extended periods of symptoms following the dislocation of parasites in the small or even large intestine(1,2). So either there was a low-grade infection that has been going on for some time, or the patient is especially indolent and suffered repeated exposures acute Anisakis infections after ingestion of his self-made foods.
On another matter, I wanted to ask how far Vincent has come with the overseas mailing of the signed PD6-copies? I ventured guesses in the past and was lucky enough to win for TWiP #162 in December 2018. However, I still did not receive the long-awaited book. I’m sorry to bother you with this but I just wanted to make sure that you didn’t ship it months ago and it got lost on the way. I attached my address below just in case.
Please keep up the great work, new episodes of your podcast are always a highlight.
All the best,
Hello TWiPle-decker hosts,
I’ve just listened to this week’s episode and I feel compelled to offer a guess for the case of the week. The symptoms from this case remind me very much of a previous case (I think from Episode 93: A Fishy Tale Unfolds) in which the individual experienced severe gastric pains shortly after consuming sushi. In this case the culprit was the Anisakis worm. What gave me pause about this week’s case was the chronic nature of the symptoms described. Anisakiasis is quite an acute ailment which can occur within hours of consuming contaminated raw or undercooked seafood, and is the result of the Anisakis worms crawling out of the contaminated meat and attempting to burrow into the lining of the stomach. The patient’s chronic symptoms made me doubt Anisakis until Dickson proposed that the individual may be continually and unknowingly reinfecting himself with his meat-preserving practice. It could be that he eats the preserved and contaminated meat regularly and never drew the connection between the stomach pain and the meat.
The other thing that seems somewhat off is that the worms that Daniel described seeing in the stomach were only a few millimeters long. Anisakis worms can be as long as 2cm when uncoiled. Could it be that these worms just happened to be somewhat smaller than the average?
Overall, I think Anisakiasis is the diagnosis I would give, even though there were a couple irregularities from what I’ve read is a typical case. Although humans are a dead-end host for this worm and won’t survive for long, they can be treated with albendazole.
Dear TWiPloid organisms,
I’ve thought long and hard about this week’s case and I just cannot come up with an answer that I’m happy with. My not so shortlist included Diphyllobothrium latum, Trichinella spiralis, Paragonimus, Strongyloides, Ancylostoma, and a few others. All fit part of the description, but not all of it. I will therefore concede defeat this week, be glad I am not making real diagnostic decisions for this man, and excitedly await the outcome!
I just wanted to add an interesting point on some of the things you covered in TWiP #173 where the idea of using RNA interference to try and characterise the Matryoshka virus was brought up. P. vivax can’t be grown in continuous culture so that would make doing genetic studies difficult anyway, but if P. knowlesi or P. falciparum, which can be cultured, could be infected with the virus; Plasmodium parasites lack RNAi machinery. They don’t have homologues to Drosha, or Argonaute or any of the RNAi genes and some had hypothesised that this potentially meant they didn’t have viruses because of the key role of RNAi in antiviral immunity. This is exactly the reason I’m doing gene knockdown experiments with a glucosamine inducible ribozyme system! Plasmodium parasites also don’t undergo non-homologous end joining when they get a double-stranded DNA break, and always need a repair template, which can make CRISPR/Cas9 gene knockouts more difficult. All bundled up with a genome that has a primer design nightmare inducing 81% AT content, I’m therefore convinced that Plasmodium has evolved to be difficult to work on in the lab, thus increasing its fitness by making it harder to develop antiplasmodial therapies J
Winter back in South Australia means today is 19oC and blue skies!
Bad, bad news for our current antimalarial drugs, the authors discover artemisinin resistance in Papua New Guinea, which has a very high prevalence of malaria. https://www.biorxiv.org/content/10.1101/621813v1.full
Treating malaria parasites with certain antibiotics kills parasites in the replication cycle after treatment in a phenomenon called delayed-death. The authors uncover the molecular basis for delayed death.
PhD Candidate – Malaria Biology Lab (Wilson Lab)
Research Centre for Infectious Diseases
School of Biological Sciences
The University of Adelaide
Wow — I learned a lot from making the wrong diagnosis for our patient in TWIP #172 — the retired physician with the bad stomach cramps and rash on his torso. To paraphrase the old medical saying, I heard hoofbeats and thought “Zebras” instead of “Horses.” And as a horsewoman myself, I should know better! hahaha In choosing between B. coli and E. histolytica, I chose the less wide-spread of the two. It really did not occur to me to even think about which was more likely to be infecting our patient, so now I’ve added that to my differential diagnosis notes.
Also, that rash! Instead of digging deeper to try to find something besides a parasite that might have caused it, I sort of ignored it, which is why it’s really probably a good thing I’m not a real medical doctor. Now I’ve noted that Samonella typhi not only can cause a rash, but is certainly something to look for when trying to complete a diagnosis, since curing the patient’s E. histolytica only to have him die of salmonella poisoning would not be a good outcome.
As for this week’s case, I did have a possible diagnosis in my head as soon as I heard the case: I’m thinking Trichinellosis, from Dr. Despommier’s favourite parasite, Trichinella spiralis.
From the CDC’s info on Trichinellosis:
“Curing (salting), drying, smoking, or microwaving meat alone does not consistently kill infective worms; homemade jerky and sausage were the cause of many cases of trichinellosis reported to CDC in recent years.”
And from PD Seventh Edition:
“Currently, prevalence of trichinellosis is low within the United States, occurring mostly as scattered outbreaks, less often involving
pork consumption and more often involving poorly cooked game, with the majority of human cases being due to Trichinella spiralis and T. murrelli.”
Also from PD7, treatment is commonly mebendazole or albendazole.
Keep the great cases coming, doctors!
Suellen in Roswell, GA.
TWiP has blindsided me with such quick turnaround from the last episode. The wormy answer is still maturing in my brain, like a larval nematode. My initial thoughts on hearing the case of the 2mm long gastric worms was some kind of nematode or less likely a diptera larva (myiasis), though that is unlikely. Also could be a nematode that is not adapted to a human host and is just hanging out for awhile. Anyway, sorry for such a larval reply. Looking forward to listening. I will up my game for the next episode, midnight oil etc etc. Happiness,
Vincent et al,
Spotted this while reading the news from home and thought it might be of some interest. I appreciate it’s not from a peer reviewed journal but a curious emergence nonetheless.
I really enjoy your program. Thanks for making it broad enough that those with a limited biology background might enjoy it.
Chitre, (pronounced Chee-tray) Panama
Just listened to episode 168. And heard the suggestion from a listener about having another interview w Peter Hotez. That sounds great I heard one interview with him that you all did a while back and it was great.
I love your podcast but think I would like to see more interviews with researchers and discussions and explanations of parasitic infections. You guys do a great job of making medical and scientific discussion accessible interesting and fun for any kind of listeners. My friends and I with animal husbandry experience love to listen to twip on road trips. We always learn so much and are well entertained.