Avian wildlife mortality events due to salmonellosis in the United States, 1985-2004

Infection with Salmonella spp. has long been recognized in avian wildlife, although its significance in causing avian mortality, and its zoonotic risk, is not well understood. This study evaluates the role of Salmonella spp. in wild bird mortality events in the United States from 1985 through 2004. Analyses were performed to calculate the frequency of these events and the proportional mortality by species, year, month, state, and region. Salmonellosis was a significant contributor to mortality in many species of birds; particularly in passerines, for which 21.5% of all mortality events involved salmonellosis. The proportional mortality averaged a 12% annual increase over the 20-yr period, with seasonal peaks in January and April. Increased salmonellosis-related mortality in New England, Southeastern, and Mountain-Prairie states was identified. Based on the results of this study, salmonellosis can be considered an important zoonotic disease of wild birds.