ParaTB (Johne's disease)

Johne’s disease or paratuberculosis is a chronic enteritis of ruminants caused by Mycobacterium avium subspecies paratuberculosis. It is endemic in Europe and the U.S.A and responsible for significant economic losses to the livestock industries through premature culling, lost productivity, infertility, susceptibility to disease, lost export markets and direct expenditure on diagnosis and control.

Young animals are more susceptible to infection and generally become infected through the ingestion of contaminated milk. There is a protracted incubation period of 2 to 4 years before infected animals show the characteristic clinical signs of diarrhoea, loss of body condition and severe wasting culminating in death. Clinically infected animals excrete the bacterium in their milk and faeces perpetuating the spread of disease.

In the UK current control measures are generally inefficient because they depend on culling or removing animals that test positive in sub-optimal diagnostic tests that lack specificity and have poor sensitivity. Vaccination is an option, although rarely used due to inherent problems with the vaccine.