An Outbreak of Epidemic Diarrhea Caused by Salmonella Nagoya Infection in Adult Dairy Cattle

Abstract

An outbreak of epidemic diarrhea in adult dairy cattle occurred on a dairy farm in Saitama Prefecture, Japan in September 2011. Nearly all of the cows in the herd suffered from anorexia, and almost half of them exhibited signs of mild to watery and foul-smelling diarrhea. Daily milk production of the herd dropped significantly. Salmonella Nagoya (SN) was isolated from all 12 of the fecal samples taken from diarrheic cows. No other pathogens were detected through bacteriological and virological examinations, so the cows were diagnosed as salmonellosis caused by SN. To our knowledge, this is the first report of diarrhea in cattle attributable to SN infection. In addition to heat stress, lactation, and calving, changes in the rumen environment due to dietary change have been considered as potential factors for this outbreak. To assess the genetic diversity and potential sources of infection, pulse-field gel electrophoresis (PFGE) profiles of the isolates were characterized and compared to that of other SN isolates previously isolated from patients, healthy cattle, and raccoons (Procyon lotor) in Saitama Prefecture. All of the isolates from the present outbreak demonstrated an identical pattern on PFGE, but they were characterized as different from previous SN isolates. In the dendrogram for PFGE, clusters of these isolates exhibited relatively low similarities (62.8‐71.7%) with the isolates from the present outbreak.