Because CtxA-antibodies are highly cross-reactive with the enterotoxigenic Escherichia coli (ETEC) heat-labile toxin (LT) (44) and because exposure to the ETEC LT toxin is a frequent occurrence for people living where cholera is endemic, it is likely that the CtxA response observed following human cholera is the result of the expansion of cross-reactive memory B cells derived from prior ETEC infection (44). The gene discussed is LTA; the disease is vibrio infectious disease.