abstract

Strains of Brucella unique to marine mammals have been cultured in many species of cetaceans and pinnipeds, and serologic evidence of exposure to these pathogenic species has been documented worldwide. Brucella has been linked to abortion, meningoencephalitis, blubber abscesses and osteomyelitis in multiple cetacean species. Despite serologic evidence of exposure and many Brucella culture isolates from pinniped tissues, there have been no instances of significant morbidity or mortality in Pinnipedia. We report here the first cases of abortion in pinnipeds associated with Brucella. During a domoic acid-producing algal bloom in a California sea lion rookery on San Miguel Island, California, 26 placentas and stillborn/aborted or moribund premature pups were collected. Culture for Brucella spp. was performed on placental tissues, and two isolates were identified, confirmed by testing at NVSL. Real-time PCR for the Brucella genus-specific bcsp31 gene amplified Brucella DNA from placentas in these two cases, and in one other that was culture-negative. Tissues from a moribund pup collected with one culture-positive placenta was found to have multifocal Brucella-positive immunostaining in macrophages in subendometrial uterine microgranulomas, and in pulmonary alveolar macrophages. These results suggest a contributory role of Brucella in abortions in this species.