Epidemiologic investigations of @entity5746 in dairy @entity291 often rely on testing fecal samples from individual animals or samples from other farm sources to determine @entity281 status. The objectives of this project were to evaluate the effect of sampling frequency on @entity5746 isolation and to compare @entity5746 isolation and serogroup classification among sample sources on 12 US dairy farms sampled weekly for 7-8 weeks. Three herds per state were enrolled from Michigan, Minnesota, New York and Wisconsin based upon predefined herd-size criteria. Weekly samples were obtained from @entity291 , bulk tank milk, milk filters, water and feed sources and environmental sites. Samples were submitted to a central laboratory for isolation of @entity5746 using standard laboratory procedures. The herd average number of @entity291 fecal samples collected ranged from 26 to 58 per week. @entity5746 was isolated from 9.3% of 4049 fecal samples collected from @entity291 and 12.9% of 811 samples from other sources. Serogroup C1 was found in more than half of the samples and multiple serogroups were identified among isolates from the same samples and farms. The percentage of herd visits with at least one @entity5746 isolate from @entity291 fecal samples increased with overall herd prevalence of fecal shedding. Only the three herds with an average fecal shedding prevalence of more than 15% had over 85% of weekly visits with at least one positive fecal sample. The prevalence of fecal shedding from different groups of @entity291 varied widely among herds showing that herds with infected @entity291 may be classified incorrectly if only one age group is tested. Testing environmental sample sources was more efficient for identifying infected premises than using individual @entity291 fecal samples.

Evaluation of herd sampling for XXXX isolation on midwest and northeast US dairy farms.

@entity281 :: ('MESH:D007239', 'Disease') :: ['herd infection'] @entity291 :: ('9913', 'Species') :: ['cattle'] @entity5746 :: ('MESH:D012480', 'Disease') :: ['Salmonella infections', 'Salmonella']
@entity5746 :: (MESH:D012480,Disease) :: ['Salmonella']
