Dynamics of endemic infectious diseases of animal and human importance on three dairy herds in the northeastern United States

Abstract

Endemic infectious diseases in dairy cattle are of significant concern to the industry as well as for public health because of their potential impact on animal and human health, milk and meat production, food safety, and economics. We sought to provide insight into the dynamics of important endemic infectious diseases in 3 northeastern US dairy herds. Fecal samples from individual cows and various environmental samples from these farms were tested for the presence of major zoonotic pathogens (i.e., Salmonella, Campylobacter, and Listeria) as well as commensal bacteria Escherichia coli and enterococci. Additionally, the presence of Mycobacterium avium ssp. paratuberculosis was tested in fecal and serum samples from individual cows. Test results and health and reproductive records were maintained in a database, and fecal, plasma, DNA, and tissue samples were kept in a biobank. All bacteria of interest were detected on these farms and their presence was variable both within and between farms. The prevalence of Listeria spp. and L. monocytogenes in individual fecal samples within farm A ranged from 0 to 68.2% and 0 to 25.5%, respectively, over a period of 3 yr. Within farm B, continuous fecal shedding of Salmonella spp. was observed with a prevalence ranging from 8 to 88%; Salmonella Cerro was the predominant serotype. Farm C appeared less contaminated with Salmonella and Listeria, although in the summer of 2005, 50 and 19.2% of fecal samples were positive for Listeria and L. monocytogenes, respectively. The high prevalence of E. coli (89 to 100%), Enterococcus (75 to 100%), and Campylobacter (0 to 81%) in feces suggested they were ubiquitous throughout the farm environment. Fecal culture and ELISA results indicated a low prevalence of Mycobacterium avium ssp. paratuberculosis infection in these farms (0 to 13.6% and 0 to 4.9% for culture-positive and ELISA-positive, respectively), although the occasional presence of high shedders was observed. Results have major implications for food safety and epidemiology by providing a better understanding of infectious disease dynamics on dairy farms. Comprehensive understanding of these infections may lead to better farm management practices and pathogen reduction programs to control and reduce the on-farm contamination of these pathogens and to prevent their further entry into the food-chain.

Molecular Epidemiology of Mycobacterium avium subsp. paratuberculosis in a Longitudinal Study of Three Dairy Herds

“…paratuberculosis. The principal strength of this study was that the isolates were obtained from samples of a longitudinal study that involves tracking infection and disease dynamics from farm to slaughterhouse (18). Slaughterhouse data are rarely collected in a large-scale observational study, because this process (i) is time and resource intensive and (ii) needs continuous coordination between the herd owner, the buying agents, the slaughter plant, and the research lab performing microbial analyses of M. avium subsp.…”

“…This project emphasizes longitudinal data collection in areas in which infectious diseases of public and animal health concern in dairy herds are endemic. For a more complete description, including information on farms, samplings, and microbial analyses, see the work by Pradhan et al (18). Briefly, the milking herds consisted of approximately 330, 100, and 140 cows on farms A, B, and C, respectively.…”

“…paratuberculosis/g of feces) for animals at each culture-positive occasion were determined (i) by additional dilutions for TNTC samples (30,31) and (ii) based on the regular colony count for samples not designated TNTC; these samples were tested by four-tube fecal culture for the presence of viable M. avium subsp. paratuberculosis organisms (18,32). To determine CFU of M. avium subsp.…”

“…paratuberculosis testing using a solid-medium culture technique as described previously (18,32). The shedding levels (CFU of M. avium subsp.…”

Review. Dairy farm management and production practices associated with the presence of Listeria monocytogenes in raw milk and beef

“…Within-herd prevalence can vary from 0 to 100% (Ho et al, 2007a;Esteban et al, 2009). In a longitudinal study of dairy herds, L. monocytogenes was isolated regularly from faecal samples in one out of three herds, with a within-herd prevalence ranging from 0% to 25.5% on a farm that was regularly found to be positive for L. monocytogenes (Pradhan et al, 2009).…”