MAP Theory
A 2010 case study reported that seven people in the same class in high school who are not related were diagnosed with Crohn’s disease, making it possible for researchers to identify some common environmental contributors that may have led this set of people to develop the disease.
Conclusions were later made that these individuals may have drunk or swam in contaminated water that contained a pathogen that triggered Crohn’s disease. According to a 2020 report, one pathogen that may cause Crohn’s is a subspecies of Mycobacterium avium called paratuberculosis (MAP).
This pathogen is known to cause a condition known as Johne’s disease in sheep, cow, and other animals that is similar to Crohn’s disease. In a 2015 research review, researchers are yet to find a direct link between MAP infections and Crohn’s disease, especially since many people who have MAP have not developed Crohn’s.
The same review also says that, even if MAP does cause Crohn’s disease, these bacteria aren’t thought to be contagious from person to person. Instead it is usually transmitted from contaminated material (such as drinking water or food) to humans.