Johne’s disease (or Paratuberculosis) in cattle, icaused by the bacterium Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic intestinal infection that leads to severe scour, weight loss, and eventually death in affected animals. The disease is slow-progressing, with cows often showing no clinical signs for years, making early detection difficult. In Northern Ireland and the UK, Johne’s disease remains a significant concern for dairy and beef farms, as it can cause reduced productivity due to weight loss, decreased milk production, and the premature culling of infected animals. Cattle usually become infected during the early weeks of life following the consumption of milk or food contaminated with the bacteria, which are shed in the dung or milk of infected adult cattle.
In the UK and Northern Ireland, efforts to control Johne’s disease have been complicated by the subclinical nature of early infection and the lack of a universal vaccination.
Diagnostic tools, such as faecal and blood testing, are used to identify infected animals, but the disease’s chronic nature often means that cattle are already spreading the infection by the time they are diagnosed. Control strategies focus on biosecurity, including isolating new animals, minimising faecal contamination of feed and water sources, and culling animals with advanced clinical disease.
