A serological study was conducted on sera and plasma from 117 wild and captive sea otters. Sera from three river otters were also tested. Sea otter sera were obtained from animals at the Monterey Bay Aquarium, animals living along the California coastline, and animals from Alaska. River otter sera were obtained from captive animals at Ocean Park Aquarium, Hong Kong.

An enzyme-linked immunosorbent assay (ELISA) was developed and used to test each serum for the presence of specific antibodies against various bacterial species. Sera were tested for antibodies directed against Vibrio alginolyticus, Vibrio cholerae, Vibrio parahaemolyticus, Salmonella newport, Salmonella pullorum, Salmonella typhimurium, Pasteurella multocida, and Staphylococcus aureus (coagulase positive). The V. alginolyticus and S. aureus cultures were isolated from sea otters. The S. newport was isolated from a California sea lion. The P. multocida was isolated from an Atlantic grey seal. The other organisms were stock cultures isolated from humans. These organisms were chosen due to their potential pathogenicity for humans as well as marine mammals.

The ELISA results were analyzed using statistical methods to determine the significant cut-off optical absorbance values for each antigen tested. Although the results varied, they indicate that sea otters are capable of responding immunologically to each of these eight organisms. The methodology used to prepare the ELISA tests, and the results obtained for these otter sera will be discussed.