MORBILLIVIRUS INFECTION IN MANATEES

The first evidence of exposure of free-ranging Florida manatees (Trich echus manatus latirostris) to a morbillivirus is reported. Blood sampl es were collected from 148 Florida manatees between 1977 and 1994. The sample included manatees that were under rehabilitation (n = 97), fre e-ranging (n = 40) and fresh necropsy specimens (n = 11). Serum from s ix animals (4%) neutralized porpoise and dolphin morbilliviruses to a higher titer than any other member of the Morbillivirus genus. Antibod ies were not detected in sera from 12 free-ranging Antillean manatees (T. manatus manatus) from Guyana sampled in 1992 or from 12 hand-reare d Amazonian manatees (T. inunguis) sampled in 1984. Immunoprecipitatio n studies using radio-labelled canine distemper virus protein and seru m from Florida manatees showed precipitation of the nucleocapsid (N) p rotein. The combination of low antibody titers and absence of clinical disease suggest that the Florida manatee is a dead-end host. Sporadic infection may occur following contact with another species in which i nfection is enzootic. Morbillivirus could, either by fatal infection o r more insidious effects on the immune system or reproduction, pose a problem to this already threatened species.