AN EVALUATION OF FACTORS AFFECTING HELICOBACTER-PYLORI PREVALENCE IN TIBETANS EXILED IN INDIA

Helicobacter pylori infection is found world-wide although the epidemiology of infection has not been well defined in many geographical areas. The aims of this study were to determine the prevalence of H. pylori infection and chronic gastritis and the demographic correlates of infection in a single racial group in southern India. The sample population was selected randomly from the male population register of a Tibetan refugee settlement. Demographic data and results of endoscopy with antral mucosal biopsy were evaluated in 197 subjects (median age 28, range 21-81 years). H. pylori was present in 77-2% of subjects by histology and/or urease test. Chronic gastritis and H. pylori were closely related and there was an association between the number of bacteria present and the severity of the gastritis (P<0.04). Infection with H. pylori was inversely associated with socio-economic factors, specifically educational level (P<0.02) and occupation (P<0.02). Unlike other studies, the prevalence of H. pylori was not found to rise with age, being lower in those older than 40 years (P<0.005). This difference was still apparent when adjusted for socio-economic status. The major demographic difference between younger and older subjects of low socio-economic status was the greater proportion of early life spent outside India (and in Tibet) by older subjects. Among younger subjects, residence in India for 20 years or more was associated with a greater risk of H. pylori infection (P<0.01). In this population from a developing country, socio-economic factors and the duration spent in a particular environment appear to be critical to the acquisition of H. pylori.