Preexisting antibodies to homologous colonization factors and heat-labile toxin in serum, and the risk to develop enterotoxigenic Escherichia coli-associated diarrhea.

Preexisting serum immunoglobulin (Ig) A and IgG titers against colonization factors and heat-labile toxin of enterotoxigenic Escherichia coli (ETEC) were examined in young adults who subsequently developed ETEC-associated diarrhea and in healthy matched controls. The data suggest an inverse association between the antibody titers against colonization factors, but not heat-labile toxin, and development of ETEC-associated diarrhea.