Herd- and individual-level prevalences of and risk factors for Salmonella spp. fecal shedding in dairy farms in Al-Dhulail Valley, Jordan.

Salmonellosis is an important disease frequently associated with diarrhea in calves. From January to September 2009, a cross-sectional study involving 91 dairy farms was conducted to determine the prevalence of Salmonella spp. infection in cattle in Al-Dhulail Valley, Jordan. A total of 910 calve and cow fecal samples were collected. Information on farm management practices was obtained through personal interviews using a standardized questionnaire and was tested as risk factors for Salmonella spp. positivity in farms by using logistic regression analysis. Standard conventional methods for Salmonella isolation and serotyping were used, and the disk agar diffusion test was used for antimicrobial testing. The herd-level prevalence of Salmonella spp. in calves, cows, and dairy farms was 12, 12, and 23 %, respectively, and the individual-level prevalence was 4 % for calves, cows, and dairy farms. Forty-six percent of the dairy farms had calf diarrhea, and 4 % had cow diarrhea. Seven (17 %) of the 42 farms with calf diarrhea had Salmonella. However, only 7 % (95 % CI: 4, 10) of the 221 diarrheic and 1 % (95 % CI: 0.2, 4) of the 234 of non-diarrheic calves had Salmonella. A total of 33 Salmonella isolates were obtained from the fecal samples: 12 isolates were Salmonella typhimurium, 6 were Salmonella montevideo, 6 were Salmonella anatum, 2 were Salmonella enteritidis, and 7 isolates were not serotyped. All isolates were susceptible to ciprofloxacin, trimethoprim-sulfamethoxazole, gentamycin, neomycin, colisitin, and amoxicillin at 100, 91, 85, 79, 79, and 70 %, respectively. Out of the 11 variables/categories, the frequency of cleaning every 2 months or more was associated with high odds of infection among calves (OR = 5.6) and farms (OR = 7.0).