DNA-based detection of <i>Mycobacterium avium</i> subsp. <i>paratuberculosis</i> in domestic and municipal water from Porto (Portugal), an area of high IBD prevalence

Mycobacterium avium subsp. paratuberculosis (MAP) may play a role in the pathology of human inflammatory bowel disease (IBD). Previously, we found high frequency (98% patients with active disease) MAP DNA detection blood Portuguese Crohn's Disease patients, suggesting this cohort has exposure to organisms. Water is an important route for dissemination, study therefore aimed assess contamination within water sources Porto area (the residential our IBD cohort). and biofilms were collected wide variety locations area, including taps connected domestic from municipal distribution systems. Baseline samples early autumn plus further winter, effect winter rainfall. was extracted all 131 IS900-based nested PCR used presence. Our results show positivity (20.7% 41.4% biofilm samples) even higher amongst (30.8% 50% samples). correlated same sources. A significantly MAP-positivity observed during rains as compared prior rainfall period (61.9% versus 30.8%). We conclude that region have burden prevalence increases hypothesize local supplies commonplace represents major transmission challenge which, if positively linked pathology, contribute district.