What is Johnes disease and what causes it?
Johne’s (pronounced “Yoh-nees”) disease and paratuberculosis are two names for the same animal disease. Named after a German veterinarian*, this fatal gastrointestinal disease was first clearly described in a dairy cow in 1895. A bacterium named Mycobacterium avium ss. paratuberculosis (let’s abbreviate that long name to “MAP”) causes Johne’s disease. The infection happens in the first few months of a fawn’s life but the animal may stay healthy for a very long time. Symptoms of disease may not show up for many months to years later. This infection is contagious, which means it can spread from one animal to another, and from one species to another (cows to goats, goats to sheep, etc.) MAP is hardy – while it cannot replicate outside of an infected animal, it is resistant to heat, cold and drying. See “Biology of M. avium ss. paratuberculosis” for more information about this bacterial pathogen. (*Dr.