Paratuberculosis or Johne's disease is a chronic and contagious infection. It mainly affects the small intestine of ruminants. All ruminants are susceptible to paratuberculosis, which is caused by a bacteria known as Mycobacterium avium subspecies Paratuberculosis. The disease is  global.

A fecal-oral route effects the transmission of paratuberculosis. After ingestion of infected pasture and water, bacteria enters through the lymph nodes (Peyer plates) of the small intestine, infecting the ileum, cecum, colon, nodes and vessels related to mesenteric lymph nodes. This causes a thickening of the intestinal walls that prevents the absorption of nutrients that can result in death. Neo natal and young animals are more susceptible to this infection.

This disease is characterized by a long incubation period, during which the infection can be very difficult to detect. The majority of infected animals show no clinical signs up to the age of two years, although the disease develops at an earlier age in some animals.

Vaccination is a key tool in controlling paratuberculosis. Vaccination coupled with proper management and hygiene of a herd helps to control the spread of the disease and to reduce the risk of infection.

Vaccination programs vary regionally, depending on the prevalence of paratuberculosis, the management of the herd/flock, size and structure, etc.

Vaccination controls paratuberculosis at all stages of the disease. Thanks to vaccination, the animals develop an immune response to M. paratuberculosis preventing the bacteria from lodging in the small intestine.

In infected animals, vaccination delays the onset of clinical signs, thus reducing the mortality rate.

Vaccination is an important tool for increasing productivity. The cost benefit of vaccination programs not only takes into account the reduction of mortality and the level of infection in a herd, but also avoids future economic losses that would materialise if vaccination were not performed.