Crohn's disease used to be thought of as a non-transmittable, presumed auto-immune disease due to documented over-reaction of the immune response and familial occurrence with increased incidence among Jews of middle European origin. Unfortunately, research in genetic markers has still not been successful in identifying genes that would make certain people at risk of developing this disease. Higher prevalence in certain families and in tightly nit communities like Jewish may also indicate that closer contacts and exposure to Crohn's patients influence the increased numbers of cases. Genetic influence exists in many communicable diseases that have been proven to be caused by an infectious agent. Studies that came after discovering the infectious agent in these disease (Helicobacter pylori in gastric ulcer, HCV virus in hepatitis C, to name the few) have shown that for each patient that develops the disease there is at least 10 "healthy" individuals that harbor the infectious agent but are resistant to it at the present time. The same may prove true for Crohn's disease in the future. There is also ample evidence that environmental factors have a strong influence in Crohn's disease: predominance of cases in urban vs. rural communities, increased incidence in immigrants that come from countries with very low prevalence of Crohn's disease, occurrence in married couples greater than expected by chance, reports of clusters on unrelated affected individuals sharing the same household or geographic area. Here are the mentioned areas of research:
Crohn's disease
- is it mildly communicable? - the latest reference
discussion on causes of Crohn's disease
animal experiments in transmission of the disease
higher occurrence in married couples
clusters of unrelated affected individuals
tests in household members and contacts
other supportive studies
prevention
according to Edward Siguel, MD PhD
note: a lot of research is dated in the late 1970's and mid-1980's because the public interest and funding was sparked by reports of steady incidence increase of Crohn's disease throughout the developed world (mostly the U.S. and western Europe). Since then, incidence leveling off has been reported and funding got channeled into HIV, Helicobacter pylori, breast cancer and some other fields, leaving Crohn's disease on the margins of public and health community interest.