Mycobacteria see ⇒ Testing for Specific Diarrhoea Pathogens (Bacteria)
Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, also called Johne’s disease, a chronic granulomatous enteritis in ruminants. The disease is globally distributed. In addition to domesticated ruminants (cattle, sheep, goat), also wild ruminants and camelids can be affected. MAP could also be isolated from other animal species, e. g. rabbits, mice, foxes and ferrets. The pathogen is very stable and can remain infectious in the environment for up to one year.
Normally, an infection already occurs orofaecally in calves through contact with faeces of infected animals, but it can also spread through the colostrum and milk, and intrauterine infections are possible as well.
The incubation period varies greatly and can take several years. The first clinical signs often tend to occur when the animals are already older than 2 years. Primary signs are continuous, profound, uncontrollable diarrhoea and progressive weight loss with regular appetite. Paratuberculosis is always lethal. Already prior to the onset of these signs, decreased milk production, reduced fertility, etc. lead to high economic losses. Not all the infected animals develop clinical signs, subclinically infected carriers also (intermittently) excrete the pathogen. Animals suspected of being infected should be isolated and, in case of a positive result, should soon be eliminated from the population or slaughtered.
Test results vary depending on the phase of infection, therefore, the use of repeated sampling is recommended if an infection is suspected!
In Germany, it is a notifiable disease in cattle, sheep and goats!