Friday, July 29, 2016

Answer to Case 407

Answer: anisakid larva, most likely Pseudoterranova species.

This case is a dramatic example of what you can find if you don't cook your fresh, unfrozen salmon before eating it! Anisakids (Anisakis spp. and Pseudoterranova spp.) are very common in wild-caught salmon, cod, and other fish, and therefore, fish should be fully cooked or frozen prior to being ingested. Freezing at -20C for 24 hours would probably kill any anisakids, but the trematodes and cestodes are a bit more resilient. Therefore, the FDA recommends freezing fish at -20C for 7 days, or -70C for 24 hours before consuming it raw or undercooked.

Differentiation of Anisakis from Pseudoterranova usually requires close examination of the larva, looking for the cecum. However, Blaine kindly pointed out that you can actually catch a glimpse of what is most likely the cecum in the video I provided. Here is a still image from the video:
The arrow points to the light tan structure which is most likely the cecum. 

Here is an image of a live Pseudoterranova worm from the CDC DPDx group for comparison (arrow points to the cecum):

To answer the question about patient management - no treatment is necessary unless the patient is symptomatic, at which time albendazole and/or endoscopic examination to remove an embedded worm may be needed. Prophylactic albendazole could also be given, but there are no clear-cut recommendations on this. 

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