Abstract

Mycobacterium avium subspecies paratuberculosis (MAP) is a gastrointestinal pathogen of ruminants worldwide.  MAP is found in the majority of dairy cattle herds in both the US and Europe where it both costs farmers in decreased production, and is an animal welfare concern for clinical animals.  The survival of this bacteria in processed dairy products and potential link to Crohn’s disease also create a potential food safety concern.

In this talk I will present our initial models of MAP transmission in closed US dairy farms, as well as developments to these models based on current longitudinal field data and experimental infections. Through the Regional Dairy Quality Management Alliance study, we have longitudinal field data from three northeastern US dairy farms for more than 6 years.  In addition to sampling animals semi-annually on the farm, tissue samples collected at slaughter have proven essential to understanding true within-herd prevalence and infection progression within hosts.  Short sequence repeat typing on all positive animals from a single farm has additionally allowed examination of questions of vertical transmission and adult infection.  Co-infections with multiple MAP strains may prove important to determining individual animal progression pathways. By combining our field data with our modeling efforts, we hope to address this real world problem and improve our understanding of the true impact of intervention strategies.