Epidemiological Features ofHelicobacter pyloriInfection in Developing Countries

Abstract

Helicobacter pylori infection has a worldwide distribution, and it has distinct epidemiological features in developing countries. In contrast to that in developed countries, H. pylori infection in developing countries seems to be nearly universal, beginning in early childhood. Children become infected in the first few months of life; in some communities as many as 50% of the children are infected by the age of 5 years, and up to 90% are infected by the time they reach adulthood. In some developing countries with improvements in industrialization, socioeconomic conditions, and hygiene, infection rates are lower. The incidence of H. pylori infection, determined indirectly, also suggests a rate several times higher than that in developed countries. Marked differences in H. pylori seroprevalence have been observed between various ethnic and racial groups. Although the mode of transmission of H. pylori remains uncertain, evidence suggests person-to-person transmission occurs.

Helicobacter pylori: recent advances in the study of its pathogenicity and prevention

“…By the age of five, as many as 50% are already infected, and by the age of 40, 90% are infected. 40 Prevalence rates are lower in developing countries with better industrialization, public health, and living conditions. Nevertheless, the rate is still several times higher than that found in developed countries, where the incidence of H. pylori infection is found in approximately 30% of the adult population.…”

Common Genetic Variations in the MUC5AC Gene are Not Related to Helicobacter pylori Serologic Status

“…For example, there are differences in H. pylori susceptibility between African Americans and US residents of European ancestry after adjusting for socioeconomic status, age and living conditions (Graham et al, 1991). Approximately 5% to 10% of a population is never infected with H. pylori, even in the presence of high exposure rates (Bardhan, 1997). Twin study has showed that there is significantly higher concordance for H. pylori infection in monozygotic compared with dizygotic twins, with a heritability estimate in twins of 57% (Malaty et al, 1994).…”

Gastric cancer among American Indians and Alaska Natives in the United States, 1999-2004

“…58 In developing countries, prevalence approaches 90%, with most individuals infected before age 10 years. 59,60 Environmental factors other than H. pylori also influence the risk of developing gastric cancer. Consumption of fresh fruits and vegetables has been associated consistently with lowered risk of the disease.…”