Dot-ELISA for seroepidemiological study of exposure to Shigella flexneri

A seroepidemiological study for determining serum antibodies to lipopolysaccharides (LPS) of Shigella flexneri using dot--ELISA was carried out in Krabi Province, Thailand, from January 1989 to December 1990. From 363 serum samples obtained from cord blood and from venous blood of the healthy persons aged from 6 months to over 50 years, 56% and 22%, respectively, were found to be positive for specific IgG and IgM antibodies to S. flexneri LPS. The IgG prevalence was initially detected at 3-4 years of age and then rose sharply with age. In contrast, IgM was detectable earlier, with much lower prevalence than that of IgG. The highest seroprevalence values were in the age groups 30-49 years for IgG and 15-19 years for IgM. The seroprevalence of S. flexneri infection was statistically higher among males, Buddhists, businessmen, and those with elementary education. S. flexneri infection was not associated with family income, home location, eating behaviour or water supply. These seroepidemiologic data demonstrated that most of the population in Krabi Province had been infected with S. flexneri.