|Van Kessel, Jo Ann|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2008
Publication Date: 4/1/2009
Publication URL: http://hdl.handle.net/10113/29894
Citation: Pradhan, A., Van Kessel, J.S., Karns, J.S., Wolfgang, D.R., Hovingh, E., Nelen, K.A., Smith, J.M., Whitlock, R.H., Fyock, T., Ladely, S.R., Cray, P.J., Schukken, Y.H. 2009. Dynamics of endemic infectious diseases of animal and human importance on three dairy herds in the northeastern United States. Journal of Dairy Science. 92:1811-1825. Interpretive Summary: This study was designed to provide insight into the dynamics of important widespread infectious diseases on three well managed Northeastern U.S. dairy herds. Long term, intensive sampling is needed to study the dynamics of the disease pathogens. We collected samples from individual animals and various environmental sites for a period of over three years. Our results indicate that all pathogens of interest, Salmonella, Campylobacter, Listeria, Mycobacterium avium paratuberculosis, as well as the commensal bacteria Escherichia coli and enterococci were present in the farms and that their levels varied over time on the individual farms and from farm to farm. This study has major implications for the dairy industry in that a comprehensive understanding of these infections may lead to better farm management practices to control on-farm contamination and prevent further entry of pathogens to the food-chain.
Technical Abstract: Endemic infectious diseases in dairy cattle are of significant concern to the industry as well as for public health due to 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 on three Northeastern dairy herds. Fecal samples from individual cows and various environmental samples from these farms were tested for the presence of major zoonotic pathogens (such as Salmonella, Campylobacter, and Listeria) as well as commensal bacteria Escherichia coli and enterococci. Additionally, the presence of Mycobacterium avium paratuberculosis (MAP, the causative agent of Johne’s disease in cattle) was tested in fecal and serum samples from individual cows. Test results, health and reproductive records are maintained in a database, and fecal, plasma replicates, DNA, and tissue samples are kept in a biobank. All bacteria of interest were detected in 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 67% and 0 to 24.3%, respectively, over a period of 3 years. Within Farm B, continuous fecal shedding of Salmonella spp. was observed with a prevalence ranging from 10 to 88%; S. Cerro was the most predominant serotype. Farm C appeared to be less contaminated with Salmonella and Listeria; except in summer 2005, 50 and 19% of fecal samples were positive for Listeria and L. monocytogenes, respectively. The high prevalence of Escherichia coli (90-100%), Enterococcus (75-100%), and Campylobacter (0-81%) in feces as well as their isolation mostly from manure composite samples suggested they were ubiquitous throughout the farm environment. Fecal culture and ELISA results indicated a low prevalence of MAP infection in these farms, although the occasional presence of high shedders (individual animal shedding >300 of MAP/g of fecal materials) was observed. Results from this study have major implications for food safety and epidemiology by providing a better understanding of infectious disease dynamics in 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.