The risk of Helicobacter pylori infection among U.S. military personnel deployed outside the United States.

To determine whether military personnel deployed outside the United States are at increased risk of Helicobacter pylori infection, 1,000 male U.S. Navy and Marine Corps personnel (mean age 22 years) were evaluated. Study subjects included 200 recruits, 500 shipboard personnel deployed for six months to South America, West Africa, and the Mediterranean, and 300 ground troops deployed for five months to Saudi Arabia. Among all 1,000 subjects, 247 (25%) were seropositive for H. pylori IgG antibody by an enzyme-linked immunosorbent assay; 24% of new recruits and 25% of troops who had been on active duty for a mean of four years. The prevalence of H. pylori antibody was higher among subjects who were older, nonwhite, foreign-born, and seropositive for antibody to hepatitis A virus. Among the 601 initially seronegative subjects evaluated before and after a 5-6 month deployment outside the United States, five seroconverted, for a rate of infection of 1.9% per person-year of exposure. As found in other populations in developed countries, these data indicate that among U.S. military personnel a large proportion of H. pylori infections occur before adulthood and infection is related to demographic factors. These preliminary findings also suggest that deployed U.S. military personnel may be at increased risk of H. pylori infection compared with adult populations in developed countries either from exposure in developing countries or from crowding.