Alberta Johne's Disease Initiative

摘要

Johne's disease (JD) is a chronic, progressive and contagious disease of domestic and wild ruminant animals for which there is no treatment. The cause of JD is Mycobacterium avium subspecies paratuberculosis (MAP), a bacterium closely related to thosebacteria that cause tuberculosis in animals, and tuberculosis and leprosy in humans. This bacterium is resistant to most common disinfectants and can persist in the environment under moist conditions for at least a year. Calves less than four to six months of age are generally thought to be the most susceptible to becoming infected when exposed to MAP. Current research at the Faculty of Veterinary Medicine at the University of Calgary (UCVM) is hoping to clarify the age susceptibility of cattle to becoming infected with MAP. Calves are usually infected by swallowing fecal contamination on the clam's legs and udder, and on contaminated bedding. Calves may also become infected by consuming colostrum or milk obtained from MAP-infected cows or contatninated with infected manure. Calves from cows shedding high numbers of MAP are at risk of being born already infected with MAP.