It has long been suspected as a causative agent in Crohn's disease in humans,[4][5] but studies have been unable to show definite correlation.

[6] One study has argued that the presence of antibodies against Mycobacterium avium subspecies paratuberculosis is associated with increased propensity of patients with Crohn's disease to receive biological therapy.

Professor John Hermon-Taylor of King's College London is developing a new vector type anti MAP vaccine which he claims is both curative and preventative.

One study concluded that MAP "may act as a causative agent, have a role in the context of secondary infection, which may exacerbate the disease, or represent non-pathogenic colonisation.

[12] The genome of MAP strain K-10 was sequenced in 2005 and found to consist of a single circular chromosome of 4,829,781 base pairs, and to encode 4,350 predicted ORFs, 45 tRNAs, and one rRNA operon.