Prevalence of fecal shedding of Salmonella spp in dairy herds.
OBJECTIVE
To estimate prevalence of Salmonella spp in Ohio dairy farms and to identify potential risk factors for fecal shedding of salmonellae.


METHODS
Cross-sectional study.


METHODS
105 Ohio dairy farms.


METHODS
Individual fecal samples from all mature cows in study herds were tested for Salmonella spp by use of standard bacteriologic culture procedures. Herds were identified as infected if at least 1 cow was shedding Salmonella spp. Information regarding herd characteristics, management practices, and health history were collected. Potential risk factors for herd-level Salmonella infection were identified.


RESULTS
In 31% of the study herds (95% confidence interval, 22 to 40%), at least 1 cow was shedding Salmonella spp. Six percent of 7,776 fecal samples contained Salmonella organisms; prevalence within infected herds ranged from < 1 to 97%. Herd size, use of free stalls for lactating and nonlactating cows, and use of straw bedding in nonlactating cows were significantly associated with fecal shedding of Salmonella spp, as determined by use of univariate analysis. By use of multivariate analysis, large herds were more likely to be infected than smaller herds; however, no other factors were associated with Salmonella infection after adjustment for herd size.


CONCLUSIONS
Subclinical shedding of Salmonella spp is common in Ohio dairy herds, although we could not identify specific interventions that may influence the prevalence of Salmonella spp on dairy farms. It appears that large herd size and intensive management may provide an environment conducive to Salmonella shedding and chronic dairy herd infection.
Huston
Carla L
CL
Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus 43210-1092, USA.
Wittum
Thomas E
TE
Love
Brenda C
BC
Keen
James E
JE
D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D003430:Cross-Sectional Studies; D003612:Dairying / Q000379:methods; D005243:Feces / Q000382:microbiology*; D005260:Female; D009820:Ohio / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012475:Salmonella / Q000145:classification / Q000302:isolation & purification; D012481:Salmonella Infections, Animal / Q000453:epidemiology*