Longitudinal study of Salmonella spp., diarrheagenic Escherichia coli, Rotavirus, and Coronavirus isolated from healthy and diarrheic calves in a Brazilian dairy herd.

Abstract

This prospective longitudinal study investigated the epidemiology of enteric disease associated with infections in calves aging up to 70 days. A total of 850 fecal samples were collected from 67 calves. Seventeen isolates of Salmonella spp. were recovered from feces of 11 calves (16.4%), and statistical analysis revealed no association between the presence of Salmonella spp. and clinical signs of diarrhea or age. Virulence factors of Escherichia coli were identified in 103 strains: eae (7), K99/STa (7), Stx1 (7), Stx1/eae (36), Stx1/Stx2/eae (2), Stx2 (43), and Stx2/eae (1). There was statistical association between diarrheic animals carrying E. coli Stx1/eae (+) in their feces at 2 and 4 weeks of age (P&#x2009;=&#x2009;0.003) and E. coli Stx2 (+) at 5 weeks of age (P&#x2009;=&#x2009;0.03). Rotavirus was detected in 49 (5.76%) fecal samples collected from 33 calves (49.2%). The presence of rotavirus was correlated with diarrheic feces (P&#x2009;<&#x2009;0.0001) rather than feces with normal consistency. There was a significant relationship between age group and diarrhea (P&#x2009;=&#x2009;0.001). Bovine coronavirus (BCoV) was detected in 93 fecal samples collected from 46 calves (68.6%). There was an association (P&#x2009;<&#x2009;0.0001) between diarrheic animals positive for BCoV and age groups. The results demonstrate the importance of the pathogens studied in the etiology of diarrhea in calves.