Year-round Monitoring of Salmonella Infection in Roosting Crows in Japan

Abstract

　 We investigated the monthly prevalence of Salmonella enterica and feeding habitat in roosting jungle crows (Corvus macrorhynchos) and carrion crows (Corvus corone) throughout a year. Twenty-five (2.2%) Salmonella strains were isolated from 1158 feces at their roosting or pre-roosting assembly places by culture test. The isolates included seven serotypes: Typhimurium, Kentucky, Derby, O4:i:-, Muenster, Agona, and Braenderup. Three and one isolates of Kentucky and O4:i:-, respectively, were resistant to multiple antibiotics. The prevalence of Salmonella in crows at the roosting sites was higher from September to November in 2018 (8/300, 2.7%) than from April to June in 2018 (0/246, 0.0%); therefore, the risk of Salmonella infection in crows varied seasonally. Such seasonal changes in the prevalence of Salmonella might be affected by beginning to use roosts by fledglings, susceptible to infection, in summer. All pulsed-field gel electrophoresis patterns of 13 isolates of Agona were the same, which suggested that the certain Agona strain used has established in a crow population. The crows’ feeding habitat based on pellets was characterized by livestock feed throughout all seasons. This result indicated that crows invaded into livestock areas throughout the year and it was possible that they transmitted Salmonella between livestock farms. It is hoped that this knowledge is helpful to the effective control of Salmonella transmission in livestock areas.