Geospatial and temporal changes in Wisconsin bovine Salmonella enterica isolates between 2006 and 2014

Abstract

Bovine salmonellosis carries a high economic burden for cattle operations and presents a public health risk due to zoonosis. The objective of this study was to determine the frequency and concurrent location of Salmonella enterica subspecies enterica serovars isolated in Wisconsin from bovine diagnostic samples submitted to the Wisconsin Veterinary Diagnostic Laboratory from 2006 to 2014, by using geographic information system and statistical analysis tools. Salmonella serovars and zip codes of animal location were retrospectively collected. Accessions were limited to bovine fecal and tissue samples that yielded a typeable Salmonella serovar either by culture or polymerase chain reaction. A total of 4,829 accessions were included in the study that yielded definitive Salmonella serovars. The 5 most frequently isolated serovars were Dublin [23%), Cerro (15%), Newport (14%), Kentucky (9%), and Montevideo (9%). After normalization, the region with the highest incidence was the east-central region for all serovars combined. Overall incidence decreased during the 9 years except for Salmonella ser. Cerro, which increased. Incidence of Salmonella serovars in densely populated dairy regions in Wisconsin was variable. Continued study and monitoring of the spatial disease ecology for salmonellosis in Wisconsin is warranted to improve animal health and milk production, and minimize the risk of zoonosis.