Helicobacter pylori infection in Angola: comparative epidemiological patterns identified by serology and stool antigen testing
© The Author(s), 2026. Licensed under CC BY-NC 4.0.
Abstract
Helicobacter pylori (H. pylori) is common in low- and middle-income countries, but recent data from Angola are scarce, and positivity estimates and associated factors may vary by diagnostic test used. This prospective cross-sectional sub-study, part of a five-year project on blood group polymorphisms and malaria susceptibility, compared seropositivity and stool antigen positivity to assess whether both tests identify similar epidemiological patterns. Data were collected at two Angolan healthcare facilities between July and September 2025. Of 357 individuals assessed, 172 were eligible and had complete results; no a priori sample size was calculated. H. pylori status was determined by rapid anti-H. pylori IgG serology and stool antigen testing. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were estimated for sociodemographic, clinical, behavioral, environmental, and ABO/Rh factors. Overall, 37.8% of participants were seropositive, and 30.8% were stool antigen-positive. Age ≥21 years was associated with seropositivity (OR = 2.17; 95% CI: 1.07–4.42; p = 0.041) and with stool antigen positivity (OR = 2.52; 95% CI: 1.15–5.52; p = 0.021). Living outside Sequele was associated with both outcomes (OR = 4.82; 95% CI: 2.27–10.21 and OR = 5.00; 95% CI: 2.17–11.51, respectively; both p < 0.001). Gastrointestinal symptoms showed strong associations (OR = 193.2; 95% CI: 43.2–864.4 and OR = 86.8; 95% CI: 19.8–380.8; both p < 0.001). Eating outside the home and treating water by methods other than boiling were associated with positivity, but wide CIs suggested sparse data. Sex, education, produce washing, ABO group, and Rh factor showed no significant associations. Both tests showed broadly similar patterns, although positivity rates and effect sizes differed. Because antibodies can persist after past infection, whereas stool antigen reflects current infection, the two tests are not equivalent measures of active infection. These facility-based findings do not represent national prevalence; larger, representative studies are needed across Angola.