Abstract
A variety of fungal diseases have been reported in cetaceans. Disseminated histoplasmosis, caused by Histoplasma capsulatum
var. capsulatum was recently described in an Atlantic bottlenose dolphin (Tursiops truncatus). Opportunistic infections are most often seen
in patients with impaired cellular immunity. Current diagnostic techniques include fungal culture, fungal stains, serologic tests for antibody, antigen
detection, skin tests, and Polymerase Chain Reaction (PCR). A 37-year-old female dolphin died after a five month illness characterized by intermittent
anorexia, lethargy, mild neutrophilic leukocytosis and mild non regenerative anemia. Culture, PCR, and histopathology confirmed the diagnosis.
Retrospective serum assays for Histoplasma antigen, performed at the Histoplasma Reference Laboratory, Indianapolis, IN indicate that the animal
had elevated antigen levels dating back to 1973. It is interesting to note that the animal appears to have remained subclinical until 1995.
In another case, a 20-year-old male Atlantic bottlenose dolphin was recently diagnosed with disseminated histoplasmosis on the basis
of elevated circulating antigen levels. Retrospective serum assays on this animal found antigen levels consistent with infection dating back to 1978.
Initial attempts at isolating Histoplasma from bronchoalveolar lavage fluid and whole blood prior to initiation of treatment were unsuccessful.
This case is currently under treatment with 600 mg fluconazole (2.8 mg/kg) po sid and 40 mg megesterol acetate (<0.2 mg/kg) po sid. Historical clinical
and laboratory findings in this animal have included: anorexia, lethargy, leukocytosis, anemia, and elevated serum transaminase levels.
References
1. Jensen E, Lipscomb T, Van Bonn W, Miller G, Fradkin J, Ridgway S. Disseminated histoplasmosis in an Atlantic bottlenose
dolphin (Tursiops truncatus)--accepted for publication, J. Zoo Wildl. Med.
2. Sweeney JC, Migaki G, Vainik PM, Conklin RH. 1976. Systemic mycoses in marine mammals. J. Am. Vet. Med. Assoc.
169: 946-948.
3. Wheat LJ. 1993. Diagnosis of histoplasmosis--review of current methods. In: Dimorphic fungi in biology and medicine.
Plenum Press, New York, NY. Pp. 333-340.
4. Wilson TM, Kierstead M, Long JR. 1974. Histoplasmosis in a harp seal. J. Am. Vet. Med. Assoc. 165: 815-817.