Abstract

A stranded adult female bottlenose dolphin (Tursiops truncatus gilli) succumbed to a pulmonary infection by Coccidioides immitis. The dolphin initially stranded on a beach in San Diego, California (117°15 min W; 32° 51 min N) and was transported to Sea World for rehabilitation. She presented in an emaciated condition with mild inspiratory dyspnea that rapidly worsened over 48 hours to include buoyancy abnormalities and finally death. On necropsy, caseous nodules were observed throughout the lungs and perihilar lymph nodes.

On histological examination of tissues, double walled organisms containing endospores in various stages of sporulation were observed in all sections of lungs and perihilar lymph nodes. Small foci of double walled organisms, none of which contained endospores, were also observed in the cerebral cortex. Pyogranulomatous infiltrates were only observed in the lung and perihilar lymph nodes.

A DNA Gen-Probe test performed on a purified isolate from Sabouraud dextrose agar, by the Texas Fungus Testing Laboratory, confirmed the organism to be C. immitis. Serum tested by the University of California Davis Coccidioidomycosis Serology Laboratory for antibodies to C. immitis by immunodiffusion, demonstrated a titer of 1:128 which is evidence for disseminated coccidioidomycosis in humans and other animals. The dolphin also tested negative for all known marine morbilli-viruses by the USDA Foreign Disease Laboratory.

There have been numerous reports of C. immitis infections in domestic animals, captive, and free living wildlife. Prior to the present report, California sea lions and sea otters were the only marine mammals affected. This is believed to be the first reported case of coccidioidomycosis in a cetacean.