Occurrence of Mycobacterium avium subspecies paratuberculosis Infection in Cattle in North Dakota,1995-2005.

Abstract

The objective of this study was to evaluate trends and risk factors for Mycobacterium avium subspecies paratuberculosis (MAP) shedding in cattle in North Dakota. The North Dakota State University Veterinary Diagnostic Laboratory records of fecal culture-positive MAP cases diagnosed from 1995 to 2005 were examined. Epidemiological data on clinical history, age, sex, breed, herd size and county of origin were extracted. Additionally, data on producers enrolled in North Dakota's Voluntary Johne's Disease Control Program were obtained from the North Dakota State Veterinarian's office. Data were analyzed using Geographic Information Systems Arc Info 9.1 software, Epi Info version 6 and SAS version 9.2. Of the 53 counties in North Dakota, 42 (79%) reported MAP infection (range 1-86, median 6) in both beef (n=204) and dairy cattle (n=175). Also, there was a correlation between distribution of cases by county and distribution of producers participating in the ND Johne's Disease Voluntary Control Program; participating counties had more MAP cases reported than counties without participants. The number of MAP cases reported increased during the study period with seasonal trends, as shedding was higher in winter and spring than summer and fall. Chi-square and logistic regression analyses indicated that large herds, female, beef animals and animals greater than four years of age were more likely to be categorized as high shedders of MAP than herds without these attributes.