Immunology

When an enteric infectious microorganism is highly endemic and there is a high degree of antigenic homo­geneity among the implicated strains, immunity tends to develop with age. The infectious enteric or­ganisms that fit this description and to which immu­nity is known to increase with age in endemic areas are the following: Vibrio cholerae, Salmonella typhi, enterotoxigenic Escherichia coli, Shigella, Norwalk virus, and Rotavirus. There is great hope that effec­tive immunizing agents against these organisms will be developed for use in high-risk populations.