Sunday, August 18, 2019

Case of the Week 557

This week's case was donated by Florida Fan and one of his coworkers who found this beauty in some fresh salmon:
Posterior end:
 Anterior end:


Anonymous said...

Anisakis L3 larvae, note the anterior spicule.

Bernardino Rocha said...

Agree with L3 larva of Raphidascarididae or Anisakidae (probably Anisakis sp. given it´s whitish colour). It´s difficult to tell the genus without the distinctive intestinal features (enlargemente of ventriculus, ventriculus, caecum etc.

Old One said...

The presence of an anterior boring tooth and a posterior mucron is consistent with Anisakis sp. I agree with B.R. that id would be more definitive if we could see the structure of the alimentary canal ( esophageal appendix and intestinal cecum). One would need to clear the worm with an agent like lacto phenol to see these structures without dissection.

Anonymous said...

Old One,
Wish I had just that, but I don't. I tried clearing with 100% ethanol, followed with limodene and Permount. No luck, the alimentary canal and intestinal cecum were not visible. Will try again next time.
Florida Fan

Dr. 'Wale said...


Old One said...

Contraceacum was the most common anisakid seen in Minnesota. Occurring as L4 and adults in the provrntriculus of fish eating birds primarily Pelicans and Cormorants. They are so robust, active and occur in such large numbers ( sometimes exceeding 1000 individuals in a single bird) It was thought by some observers that they might aid in the breakdown of digesting prey. The life cycle has this critter passing through intermediate and transport hosts. Like other Anisakid larvae they have an anterior boring tooth and a caudal micron. They are a common parasite of Salmonids. Could this be our unknown?

If your into doing fecals on exotic animals, eggs of Contraceacum have a thick, textured outer protein coat which is colorless.

For those of you interested in Pelican parasites there is a peculiar comma-shaped louse that lives in the gular pouch.

Blaine A. Mathison said...

Anisakid yes, the presence of a mucron should rule-out Contracaecum and Type II Anisakis. This is either Pseudoterranova or Type I Anisakis; most of what I have seen in salmon is Pseudoterranova, but most of these worms have a low host specificity for the piscine host.

By the way, with regards to clearing, alcohol is not used for clearing. Actually alcohol can interfere with morphologic analysis. Preservation in 10% formalin prior to clearing is best. The best solution for clearing is lactophenol (50-50 phenol crystals in lactic acid with glycerin).

Old One said...

Contacted some friends still in the business. They agree that Lactic acid is a safer choice for clearing nematodes. Not quite as good as lactophenol but it gets the job done,

Is it safe? Have you had your milk today?

ParasiteGal said...

Old One: thanks for the comments about the lactic acid. I've never tried that, but it's appealing since phenol wouldn't need to be used (my lead tech has a bad reaction to phenol, so we can't use it in my lab). Do you have any information about how this works? For example, the concentration and length of time needed for clearing? thanks! Bobbi