Abstract

As part of the U.S. Navy Marine Mammal Program's (NMMP) disease prophylaxis and surveillance efforts, several infectious disease agents have been identified as potential health threats to Navy animals. Not surprisingly, these microbes include viral, bacterial, and protozoan species with well-established etiologies for disease in veterinary, as well as human medicine. Of these, Brucella species stand out as an opportunistic bacterial pathogen that affects both cetacean and pinniped species. Evidence from the literature shows that Brucella species have been associated serologically with disease in various marine mammal species, and have been positively identified as the etiologic agent in infections of the epidermis, central nervous system, and placenta. Of central concern for NMMP are the phenomena of Brucella-induced abortion and osteomyelitis, and its well-established zoonotic potential. Despite the similarities exhibited thus far with known pathologies found in human and veterinary medicine, our understanding of infectious sequelae of Brucella in cetacean and pinniped species remains incomplete. Thus, the health threat to marine mammals and animal care personnel remains unclear. Currently, we are investigating the application of a molecular-based approach to detect Brucella RNA in tissues combined with comparative serology to measure the level of Brucella maris-specific dolphin IgG. Six clinical cases were investigated in Atlantic bottlenose dolphins (Tursiops truncatus) housed at the NMMP facility in San Diego, CA. In this study, we were able to demonstrate an association between the presence of bacterial RNA in affected tissues and the level of Brucella-specific IgG in peripheral blood at the time of suspect infection, and that this finding could be confirmed by traditional microbiological characterization. Moreover, these techniques were easily applied to clinical samples, as well as on archived samples for the performance of retrospective studies. It is our assertion that the combined application of RT-PCR and serology provides a rapid and accurate means with which to determine etiology and potentially disease onset. This may represent an advantage in this regard by expediting targeted treatment regimens in suspect animals.