Histolopathological Changes Observed in Three Species of Shark with Special Reference to Etiology and Ultrastructure
IAAAM Archive
E.B .May; W.D. Sheffield; M.W. Stoskopf; R.M. Jones; A.G. Smith
University of Maryland, Baltimore, MD

This paper will concentrate on three case reports which are to be published at a later date. Severe acute meningioencephalitis in a Tiger Shark (Galeocerdo cuvier) was observed characterized by a mixed cell infiltrate in the meninges, predominately neutrophiles, and diffuse encephalomalcia. Cells, which on histopathological evaluation were characterized as macrophages ("Gitter cells"), later were discovered to be ciliated cells characteristic of a protozoan. The inflammatory response was confined to the meninges with the cerebral cortex exhibiting only malacia.

Brown Sharks (Carcharhinus milberti) exhibiting signs of disorientation, and traumatic lesions to the snout as a result of that disorientation were found to have acute encephalitis, meningitis, pancreatitis, hepatitis, interstitial nephritis, and myositis. In one instance, severe hypodermal and dermal necrosis occurred, as well as a severe myositis. Specimens for bacteriological analysis yielded pure cultures of a grave negative short rod that exhibited bipolar staining and specific biochemical characteristics which under existing API or other classification schemes could be identified. The possibility of a new species of pathogen will be discussed.

An adult female Lemon Shark (Negaprion brevicostris) was presented shortly after death exhibiting signs of severe cranial distortion most severe on the left side. A wound was detected with the entry on the inner surface of the left jaw and exiting at the articulation of the upper and lower mandibles on the left side. Histologically only acute changes were seen involving the brain, kidney, liver, gastrointestinal tract, and muscle. Pseudomonas sp. was isolated from kidney, muscle, and spleen as pure cultures, as well as from the site of swelling. A discussion of the pathology of this case will be presented.

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Eric B. May
University of Maryland
Baltimore, MD


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