Case guesses:

David writes:

Dear TWiP Trio,

Although my guess from last week was incorrect, I always enjoy learning about a new parasitic disease I have never encountered in my studies.

That being said, my guess for this week’s parasitic puzzle seems to be related to last weeks guess, but with a little uncertainty attached to it: symptoms missing from last week’s case seem to be present here (jaundice, abdominal distension, mass below liver on the right-hand side (near the biliary duct). These, and Dr. Griffin’s hint, seem to point to either opisthorchiasis caused by Opisthorchis viverrini, or chlornochiasis caused by Chlonorchis sinensis. Both infections are extremely similar in their pathology and life cycles, and must be identified via egg microscopy. Both infections fall under the “Oriental liver fluke”, so I will use them interchangeably, but Opisthorchis viverrini is common in Thai dishes so I will venture that this is the organism involved.

Thank you once again for the informative podcasts,

David P.

Bryce writes:

Hello Parasite Prophets,

I would like to take a stab at the previous week’s TWiP case about the man in northern Thailand.  This is my first case study, but hopefully not my last.  

After a short patrol through PubMed, I believe this man is infected with Opisthorchis viverrini (I am very glad this is a submission in email format since I have no idea how to get my tongue around that word).  I was thinking flukes from the jaundice, which would be representative of destruction of the liver.  Prior to some of the clues dropped, I would probably have guessed the magnificent Fasciola hepatica. The bile duct and raw fish dish hints narrowed my search where I came up with O. viverrini, which also has been associated with a cancer of the gall bladder or its ducts that could explain the large, non-tender mass in the abdomen.  Additionally, it seems that this parasite is frequently found in Northern Thailand, giving it the common name of: the Southeast Asian liver fluke (a misnomer?).

Like Dr. Griffin, I would definitely try the raw fish dishes and hopefully not acquire any parasites.  Here’s to a future culinary experience free from flukes, tapeworms, or trichuris!



Um writes:

Dear Twippers

My guess is the Thai fisherman probably had liver fluke infection (Opisthorchis viverini). He probably had it for quite some time without knowing, and now he is developing the cancer of bile duct, and it is blocking the flow of bile. This is the reason he is having jaundice.   If we look at the stool sample, we should find the parasite ova that look like old fashioned light bulb.  Treatment – praziquantel and removal of the tumor by surgery.


Let me say something about Thai food,  “Som Tum”, or spicy papaya salad.

The word “Som” means “sour taste” (from lime juice + tomato).  “Tum” means crushing the food with mortar and pestle.

Basically “Som Tum” is a  spicy papaya salad, made from raw papaya, tomato, garlic, chillies, dry peanuts, green beans, palm sugar and lime juice.  Everything is mixed in the mortar and crushed briefly with a pestle.   It is a healthy food  and everyone can enjoy this dish without having stomach upset.  

By adding extra ingredients you can create many versions of “Som Tum”, depending how adventurous you want to be, for example

Som Tum THAI = is the basic papaya salad + sun dried shrimp.  I would say that this version is quite safe to eat.  

Som Tum PA – RAH = is papaya salad + raw fermented fish.

Som Tum PU – CHEM = is papaya salad + raw salted freshwater crab.


Another item of mis-understanding

Fish sauce or “Nam Pla”  not to be confused with  Fermented raw fish or “Pla Rah”

Fish sauce is made from small marine fish, for example  Stolephorus sp.  (anchovy).  This is done by mixing the  fish with salt (NaCl)  about 50/50 ratio (without adding water).    Put the slurry in a big clay pot and let it sit for one year.  Halophilic bacteria  such as Tetragenococcus spp.   will grow and digest the fish with proteolytic enzymes.   The result is  a clear amber liquid.  Local people use it as it is.  The modern  manufacturer usually boil and filter it, and then pack it in the bottle – so it is quite safe.    I guess the romans do have similar thing called “garum”.  

Fermented raw fish or “Pla Rah”  is made from freshwater fishes.  It is done by mixing the fish with rice grain, rice bran, and bit of salt (10-20%) and let it ferment anaerobically  for a few months.  The bacteria responsible for curing the fish are mostly  lactic acid bacteria.   The cured fish can be eaten raw or cooked i.e. fried.  I guess you can think of it as the “oriental pickled herring”.

Knowing this fact, next time you visit a Thai restaurant, you can start your gastronomical adventure.

Keep up the good work, and… be nice to Dickson!

Um   Pae-ra-ta-kul

Bangkok, Thailand.  


I wish that TWIM and TWIV have case study like this.  

It is currently 28 degree celsius and raining in Bangkok.  

By the way, we do get CURIOSITYSTREAM here in Thailand.

Mike writes:

Case 116. It could be Opisthorchis viverrini, common name Southeast Asian liver fluke, but hey what do I know, I am just a peon trying to survive in the Great Multimedia Empire of Lord Crislip.


Iosif writes:

Dear Twip Team,

I apologize for the capitalized OVA from the last email. I think I mixed up ova (as in eggs) and OVA (as in original video animation). I do write these in a rush and I sometimes don’t proofread well enough. I will try to do better.

My differential for this case would be:

  1. Echinoccoccus infection – When I think of a mass of the liver I generally jump to either cancer or this worm causing a cyst. Thailand is  not endemic for echinococcus, but I was able to find several cases from the past few years. If the cyst becomes large enough then it could occlude the biliary tree which then leads to the obstructive jaundice and our patient’s symptoms. Treatment would be PAIR (puncture, aspiration, injection and reaspiration).
  1. Shistosomiasis – Is fairly unlikely in this patient. Thailand is not endemic for shistosomiasis, but if the patient was in the very northeast portion of the country and came in contact with fresh water from Vietnam (where it is endemic) then I guess it cannot be ruled out. I would not expect a mass developing with shistosomiasis, but I would assume that the fibrosis in the liver that results with chronic infection could predispose someone to develop hepatocellular carcinoma, but once again this is assuming quite a lot and so this is not high on my differential. Treatment would be praziquantel.
  1. Opisthorchis Viverrini – We are taught that painless jaundice is always concerning for cancer. In this patient, I don’t see why a pancreatic cancer would form, but a cholangiocarcinoma is absolutely a significant problem in Thailand. Chronic infection with Opisthorchis is usually asymptomatic, but the chronic inflammation can predispose one to a cholangiocarcinoma. If it spread to the liver, I would imagine that it could lead to the mass that is felt on physical exam. The jaundice could be a result of obstruction of the biliary tree which is especially common if this is a Klatskin tumor. The points against this diagnosis is that this has been going on for months and cholangiocarcinoma is notorious for fairly rapid progression and death. 36 years is also still a bit young for this diagnosis. The biggest point for this diagnosis is the fact that Opisthorchis is endemic to northern Thailand and a large proportion of people are infected. Treatment would be praziquantel and surgery (most likely palliative) for the tumor.

Considering these diagnoses, I would ultrasound the patients mass (it is cheap and safe if available). This should easily identify a fluid filled cyst vs. something else. If the mass is not fluid filled, then a CT scan may be needed, especially if we think this is cancer in order to determine if there are metastases elsewhere.


Iosif Davidov

P.S. I recall on Twiv there was a discussion on post-cholecystectomy fat absorption. Without a gallbladder, the liver is constantly secreting bile salts into the duodenum so fat is still digested properly. If someone has diarrhea after cholecystectomy it is more likely due to bile salt malabsorption since without fat the bile salts cannot be reabsorbed properly and can lead to a secretory diarrhea. As to the question of whether or not cholecystectomy affects norovirus infection, I would assume based on these observations that it would not affect infection rates. Sorry for putting this here, but it seemed appropriate with all the talk about the biliary tree.


Steve writes:

Hi TWiPsters,

Makes you think: Mosquitoes can be successfully trapped with ‘baits’ that include carbon dioxide (mimicking our breathing), but to produce the CO2 where needed would be equivalent to providing an extra meal per day to the affected peoples. Discuss.

“The quantities of carbon dioxide in existing lures are comparable with those generated by a living human being. As a result, inclusion of carbon dioxide in the mixture released by the traps deployed in this study would require a similar quantity of reduced carbon to providing everyone on Rusinga Island with an extra meal or a bus trip to the mainland every day.”‎





Mercifully cool and fresh after overnight storms.

Sofie writes:

Dear Twip-team,

In the latest episode (no. 116) Vincent asked about parasites in Japan. I know Daniel and Dickson can tell you much more about this but it made me think of Katayama fever!

I’m an M.D. and I heard about Katayama fever in med school. It is the acute manifestation of infection with Schistosoma sp. and used to be common in Japan before Japan became a rich and developed country.

As I recall, and please do correct me if I’m wrong Daniel and Dickson, there was at least one village/area in Japan where Schistosomiasis was so common that when women married men from other areas of Japan, the men would become very sick and potentially die very shortly after the men started working in the rice fields. This was supposedly due to the massive exposure to Schistosomes of completely (immune) naïve individuals whereas the locals had built up some sort of immunity and most likely were already infected. Rice fields are full of fresh water as you know and this was the perfect place for Schistosoma to be transmitted when the whole village worked all day in the rice fields. I have not been able to find anything to substantiate this story online or in Harrison’s internal medicine. Supposedly this story is why the acute manifestation of Schistosomiasis is named after a place (?) in Japan.

My brother in law was born and grew up in Japan and I had the priviledge to visit him and my sister in Japan with my mother and brother back in 2010. And I totally agree with you Vincent, it is an amazing place!! I really loved it and would love to go back.

Thanks for a wonderful podcast and keep up the good work.


Leave a Reply

Your email address will not be published. Required fields are marked *