Johne’s Disease (Paratuberculosis)

Johne’s disease, also known as paratuberculosis, is worldwide in distribution and many countries have national control programmes for this disease. It has a global distribution. The infective organism of the disease is resistant to heat, cold and drying, and can survive for extended periods in soil and even longer in water. This disease also has zoonotic importance and can be defined as a chronic infectious enteric disease that affects domestic and wild ruminants. It is characterized by a slowly progressive wasting of the animal and increasingly severe diarrhoea. It is caused by Mycobacterium avium subsp. paratuberculosis (MAP), which is common in the environment but does not multiply outside a living host. Infection is mainly spread by the faecal–oral route. Generally the age of onset of faecal shedding and clinical disease varies with dose, age of infection, host susceptibility to infection and herd management factors. Faecal shedding can be intermittent and usually precedes clinical signs. In goats, the main clinical signs are cachexia, production loss, a dull and crustaceous hair coat, exercise intolerance, selective food intake (leaving the concentrate) and sometimes intermittent diarrhoea. Diagnosis is generally performed on the basis of clinical signs, histopathology evaluation, post-mortem lesions and diagnostic tests.