Opossums as a reservoir for Salmonellae

Approximately 200 opossums, trapped during the fall of 1973 in the vicinity of Raleigh, NC, were maintained in the Institute's breeding colony in individual cages until the breeding season. Clinically normal, dead, and moribund opossums were examined for Salmonella. Six serotypes of Salmonella were identified in both clinically normal and diseased opossums. Positive culture results were obtained on 39 of 56 (70%) rectal swab specimens collected in the fall from incoming opossums, and on 30 of 50 (60%) rectal swab specimens collected during midwinter from an additional group of clinically normal opossums, which were maintained in isolation for approximately 3 months before testing. At necropsy, 87 of 108 (81%) diseased opossums were culture positive for Salmonella. Salmonellae in serogroups B and R were isolated from the spleen, liver, kidneys, or heart blood as well as the ileum of 57 diseased opossums. In 23 cases, S typhimurium or S bern was isolated in pure culture from the visceral organs. These findings indicated bacterial septicemia. In contrast, salmonellae in serogroups C1, E1, and F were routinely isolated from the feces of clinically normal and diseased opossums, suggesting a habitat restricted to the intestinal tract and probably the mesenteric lymph nodes. It was concluded that the opossum serves as a reservoir for a number of serotypes of Salmonella and may have an important role in the epizootiology of wildlife salmonellosis.