Mycobacterium avium subspecies paratuberculosis (MAP) is an infectious factor recently found in association with multiple sclerosis (MS) in Sardinia.

The objectives of this study were to confirm this association and evaluate its role in clinical features.

A total of 436 patients and 264 healthy controls (HCs) were included. We examined the blood of each individual for MAPDNA and MAP2694 antibodies using IS900-specific PCR and ELISA, respectively. Differences in MAP presence between the MS group and HCs were evaluated. In MS patients, we considered: gender, age, age at onset, duration of disease, course, EDSS, therapy, relapse/steroids at study time, and oligoclonal bands (OBs).

MAPDNA and MAP2694 antibodies were detected in 68 MS and six HCs (p = 1.14 x 10^–11), and 123 MS and 10 HCs (p = 2.59 x 10^–23), respectively. OBs were found with reduced frequency in MAP-positive patients (OR = 0.52; p = 0.02). MAP2694 antibodies were detected more in patients receiving MS treatments (OR = 2.26; p = 0.01), and MAPDNA in subjects on steroids (OR = 2.65; p = 0.02).

Our study confirmed the association of MAP and MS in Sardinia. The low OB frequency in MAP patients suggests a peripheral role as a trigger in autoimmunity. MAP positivity might be influenced by steroids and MS therapy. Studies in other populations are needed to confirm the role of MAP in MS.