HISTOLOGIC, IMMUNOHISTOCHEMICAL, AND POLYMERASE-CHAIN-REACTION STUDIES OF BOTTLE-NOSE-DOLPHINS FROM THE 1987-1988 UNITED-STATES ATLANTIC COAST EPIZOOTIC

Tissues from 95 bottlenose dolphins (Tursiops truncatus) that died dur ing the 1987-1988 US Atlantic coast epizootic and 11 bottlenose dolphi ns that died along the Atlantic coast prior to 1987 were examined hist ologically and immunohistochemically. Polymerase chain reaction (PCR) testing was performed on 36 of the epizootic and all of the pre-1987 c ases. Epizootic cases had syncytia and rare intranuclear and intracyto plasmic inclusion bodies within lung, lymph node, and spleen. Lymphoid depletion was present in lymph node, spleen, and gut-associated lymph oid tissue of epizootic cases. Pre-1987 cases did not have these pulmo nary and lymphoid lesions. A larger percentage of epizootic than pre-1 987 cases had bacterial and/or fungal infections (primarily pneumonias ), pulmonary and lymphoid tissue histiocytosis, mucocutaneous ulcers, and evidence of negative energy balance. Immunohistochemically, 49/95 (52%) epizootic dolphins were positive for morbilliviral antigen. Morb illiviral antigen was detected in lung, lymph node, spleen, thymus, sk in, tongue, esophagus, liver, pancreas, gastrointestinal tract, urinar y bladder, oviduct, and mammary gland by immunohistochemistry. PCR tes ting identified morbilliviral RNA in 35/36 (97%) epizootic cases teste d. Neither morbilliviral antigen nor morbilliviral RNA were detected i n pre-1987 cases. Histologic, immunohistochemical, and PCR results pro vide strong evidence that morbillivirus infection was the primary caus e of the 1987-1988 bottlenose dolphin epizootic.