Johne’s disease is a contagious, chronic, and usually fatal infection that primarily affects the small intestine of ruminants. All ruminants are susceptible to the disease, which is caused by Mycobacterium avium subspecies paratuberculosis, a hardy bacteria related to the agents of leprosy and tuberculosis. The disease is worldwide in distribution.
What test do I choose for direct detection of the causative agent of Johne’s disease?
WADDL recommends Mycobacterium avium subsp. paratuberculosis (MAP) detection be performed using polymerase chain reaction (PCR). A major advantage of the PCR test is that results will usually be available in a week or less compared to months for culture.
What samples do I need for PCR?
Feces or intestine should be collected and shipped chilled with a frozen gel pack. PCR has not been validated on other tissues and may be cultured by special request.
What other test options are available for Johne’s disease?
Serology currently plays a role in the control strategies outlined in the United States Department of Agriculture’s Uniform Methods and Rules (Cattle Disease Information/Johne’s Disease Info) or other published control programs (Collins MT, et al. Consensus recommendations on diagnostic testing for the detection of paratuberculosis in cattle in the United States. JAVMA, 229(12):1912-1919, 2006).