Leprosy is not caused by organisms entering the gastrointestinal tract. The polio virus is often transmitted by drinking water contaminated with the polio virus especially in regions with low hygiene standards. Infant botulism is caused by ingesting spores of the strain C. botulinum. In the small intestine, the spores start to colonize and multiply. The cause for adult listeriosis is in most cases the ingestion of food contaminated with L. monocytogenes.
