Risk of Helicobacter pylori infection among long-term residents in developing countries

The seroprevalence and incidence of Helicobacter pylori infection were dete rmined among 312 North American missionaries who were serving in developing countries between 1967 and 1984. The majority (81%) resided in sub-Saharan Africa. When initially evaluated, the missionaries had a mean age of 40 ye ars, 65% were female, and all were of white race/ethnicity. An ELISA showed that the initial prevalence of IgG antibody to H. pylori was 17%. After a mean of 7.4 years of service (1917 person-years of exposure), 37 (14%) of 2 59 initially seronegative subjects seroconverted to anti-H. pylori, giving an annual incidence of 1.9%. These data indicate a relatively higher risk o f H. pylori infection among missionaries compared with an annual incidence of seroconversion of 0.3-1.0% in industrialized nations. Long-term resident s in developing countries should be evaluated for H. pylori infection when gastrointestinal symptoms develop.