Here is a closer look.  The back marks are 1mm each.

Further identification requires examination of internal structures, which is traditionally accomplished by clearing, staining, dehydrating, and mounting.  As I am more veterinarian then parasitologist, I opted to turn the specimens into biopsy samples and had them processed into standard H&E 5um slides.  Here is a full worm spread out on a composite digital micrograph.

What is the parasite?

How does it relate to the stranding?

How would you diagnose the infection with a dolphin in rehabilitation?

enjoy . . .

These are roundworms or nematodes.  The first clue was obscured in the original post (didn’t think I was going to make this too easy did you?) and required you to look at the oral opening and the three lips (covered in this case by the capsule). This and the marine mammal host place them in the family Anisakidae.

Here is a close up of the lips from another specimen (in this case a harbor seal, likely a different genus), each red arrow points to a “lip”.

The capsule (a molt) and the point on the terminal end (a mucron), combined with the  lack of spicules or eggs, identifies this as a larval form (L3).

This is a classic group of marine nematodes where the adults inhabit marine mammals and the larva use a huge number of different intermediate and transport hosts.  The Anisakidae are further classified into their respective genus by the morphology of their esophagus, ventriculus and presence or lack of an intestinal caecum (see chart).  In this case, the simple ventriculus identifies the genus Anisakis.

The species identification requires the adult (or L5) males which were not observed in this case.

Many reviews of the Genus Anisakis (Dujardin, 1845) have been published; for the truly geeky see the following:  Davey 1971; Abollo and Pascual 2002.

Known species of Anisakis:
A. physeteris (Baylis, 1923)
A. typica (Diesing, 1860)
A. simplex (Rudolphi, 1809) senso lato complex (with 13 synonyms)
A. simplex s.s.
A. pegreffi (Campana, Rouget & Bioca, 1954)
A. simplex (Nascetti et al., 1986)
A. ziphidarum (Paggi, et al., 1998)
A. brevispiculata (Dollfus, 1966)

Of these,  A. simplex , A. brevispiculata, and A. physeteris have all been found in Kogia.

The larval forms are zoonotic and can be pathogenic to the host, particularly in large numbers or when they cause ulceration.  The worm in the blowhole was likely aspirated as a terminal event, as the worms are inhabitants of the stomach. The genus is intensely studied as the larval worms are human health hazards, typically encountered by eating improperly cooked fish and resulting in the unpleasant disease called Anisakiasis.  Recent genetic studies may hold the key to correct identification of larval forms.

The best way to handle them (besides “with gloves” which I also accepted) is to wash them by shaking them in a jar with 0.9% saline to remove blood and mucous, then fix them in near boiling saline for 5 seconds to straighten the worms, then move them to a vial with 70% ethanol and add a few drops of glycerin.  They can also be fixed in glacial acetic acid for a few hours and stored in 70% ethanol with a few drops of glycerin added.

One Health is the intersection with veterinary care and science, environmental degradation, and human health.  One of the many examples involves the study of middle ear infections in seals, which are often severe and involve the bones of the skull.  This infection is associated with coliform bacteria and an increase in the incidence of this disease in seals could signal environmental pollution with these bacteria.  Otitis media is also a common illness in human children; complications and bone infections are rare but potentially devastating.  It may the environmental role or the unique anatomy of seals which includes a flap that prevents water from entering the ear canal and also prevents drainage from infection, but seals are an excellent disease model for a human disease.  By treating and studying these naturally occurring diseases we hope to benefit the seals, the environment, and human health care.

Dr. Williams address the group at PCCS

Topics ranged from advanced diagnostic techniques, a veterinary continuing education session, and the concepts of One Health, and global surveillance through the use of marine animals.

Dr. Williams addresses the main auditorium

Dr. Dunnigan and David Schofield of NOAA examine the posters

For more information, contact Dr. Sea Rogers Williams, Science Director and Associate Veterinarian.