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Title: Longitudinal data collection of Mycobacterium avium subspecies Paratuberculosis infections in dairy herds. Collection and use of observational data

Author
item SCHUKKEN, YNTE - Cornell University
item WHITLOCK, ROBERT - University Of Pennsylvania
item WOLFGANG, DAVE - Pennsylvania State University
item GROHN, YRJO - Cornell University
item BEAVER, ANNABELLE - Cornell University
item Van Kessel, Jo Ann
item ZURAKOWSKE, MIKE - Cornell University
item MITCHELL, REBECCA - Centers For Disease Control And Prevention (CDC) - United States

Submitted to: Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2015
Publication Date: 6/19/2015
Citation: Schukken, Y., Whitlock, R., Wolfgang, D., Grohn, Y., Beaver, A., Van Kessel, J.S., Zurakowske, M., Mitchell, R. 2015. Longitudinal data collection of Mycobacterium avium subspecies Paratuberculosis infections in dairy herds. Collection and use of observational data. Veterinary Research. 46:65-75.

Interpretive Summary: Johne’s disease (JD) is a chronic enteric disease of cattle and other ruminants due to an infection with Mycobacterium avium subsp. paratuberculosis (MAP). In a 2007 USDA survey, it was found that 68% of US dairy herds have at least one cow that is infected with MAP. The cost of MAP infections to US dairy producers was estimated to be more than $200 million per year. This disease is difficult to study in herds because the infection is very slow to progress, many infected animals never show clinical signs, are only detected a few years after initial infection, or are actually never detected. We collected longitudinal MAP infection data on three dairy farms in Northeastern United States during approximately 10 years. Fecal samples were collected and tested from cows biannually and blood samples were collected quarterly. Approximately 13,000 serum samples, 6,500 fecal samples and 2,000 tissue samples (at slaughter) were collected during these years. Prevalence of positive samples was 1.4% for serological (blood) samples, 2.2% in fecal samples and 16.7% in tissue samples. Infection dynamics of MAP was studied and resulted in a number of important changes in MAP paradigms. First, following cows over their lifetime (versus one time sampling) revealed a high prevalence of MAP infection in these. Second, two distinctly different infection patterns were observed; some animals displayed intermittent and low shedding of MAP bacteria with no humoral immune response,while infections in other animals were characterized by continuous and progressive shedding and a strong humoral immune response. Continuous high quality longitudinal data collection turned out to be an essential tool in our understanding of pathobiology and epidemiology of MAP infections in dairy herds. Results from this survey will help to develop improved methods for controlling JD in US dairy herds.

Technical Abstract: Longitudinal infection data on Mycobacterium avium subspecies paratuberculosis (MAP) was collected on three dairy farms in Northeastern United States during approximately 10 years. Precise data on animal characteristics and animal location within farm were collected on these farms. Cows were followed over time with regard to MAP status during biannual fecal and serum sampling and quarterly serum sampling. Approximately 13,000 serum samples, 6500 fecal samples and 2000 tissue samples were collected during these years. Prevalence of positive samples was 1.4% for serological samples, 2.2% in fecal samples and 16.7% in tissue samples. Infection dynamics of MAP was studied and resulted in a number of important changes in MAP paradigms. First, a high prevalence of MAP infection was observed in these herds due to lifetime follow up of cows, including slaughter. Second, two distinctly different infection patterns were observed, so called non-progressors and progressors. Non-progressors were characterized by intermittent and low shedding of MAP bacteria and a virtual absence of a humoral immune response. Progressors were characterized by continuous and progressive shedding and a clearly detectable and progressive humoral immune response. Strain typing of MAP isolates on the three farms identified on two of three farms a dominant strain type, indicating that some strains are more successful in terms of transmission and infection progression. Continuous high quality longitudinal data collection turned out to be an essential tool in our understanding of pathobiology and epidemiology of MAP infections in dairy herds.