Nationwide survey of Helicobacter pylori seropositivity and gastric atrophy in Zambia.

BACKGROUND: Helicobacter pylori (H. pylori) is a common bacterial infection which predominately drives upper gastrointestinal pathology. We carried out a nationwide serological survey in response to the deficiency of robust African data on H. pylori prevalence, age of acquisition, socio-geographic determinants, and impact on gastric physiology.

MATERIALS AND METHODS: This was a cross-sectional study of archival plasma samples collected during the Zambia Population-based HIV impact Assessment (ZAMPHIA) 2016 survey. ZAMPHIA used a two-stage door-to-door stratified cluster sample approach to collect samples from adults and children from age 0 to 59 years (n = 24,266). We randomly retrieved one fifth of these samples from each of Zambia's 10 provinces and used ELISA to test for H. pylori IgG antibodies, pepsinogen 1 and 2 and gastrin-17. A pepsinogen 1:2 ratio of <3 was used to define gastric atrophy.

RESULTS: The analysis of 4050 plasma samples (30% <16 years, 53% females) revealed an overall H. pylori seroprevalence of 79%. By the age of 10 years, more than 75% of the children had H. pylori. Urban residence was associated with increased odds (OR 1.8, 95% CI 1.5-2.2, p < 0.001) and HIV infection was associated with reduced odds (OR 0.7, 95% CI 0.5-0.9, p = 0.02) of H. pylori seropositivity. Gastric atrophy was detected in 6% of H. pylori seropositive adults below 45 years of age and 9% in those between 45 and 59 years.

CONCLUSIONS: We have confirmed a high prevalence of H. pylori seropositivity in Zambia, predominantly in urban settings. The prevalence of gastric atrophy is broadly consistent with other populations around the globe, but our sample did not include adults over 60 years.