Serosurvey and Risk Analysis for Distemper Virus of the Captive Phocid Population in the United States
Antibodies to distemper virus have been documented in free-ranging pinnipeds throughout the Atlantic and Arctic Ocean populations, but never documented in the Pacific Ocean populations. Risks for spreading this Morbillivirus through the captive North American phocid population to the Pacific coast have been a concern. To date, the serologic status of this dynamic captive population is undocumented. From 25 North America zoos and aquaria, serum was submitted from gray seals (Halichoerus grypus, n=7) and harbor seals (Phoca vitulina, n=96) and assayed for distemper virus via serum neutralization. Historic and environmental risk factors associated with the acquisition and distribution of distemper virus were analyzed by survey. Fourteen seals (gray n=1, harbor n=13) were documented with seropositive titers (≥1:24) indicative of exposure to distemper virus. These seals were distributed across the continent, including the Pacific coast, signaling an as yet undocumented risk to the Pacific pinniped population.