Transmission pathway of Helicobacter pylori: role of food in rural and urban areas

Why it matters

According to the researchers, the transmission route of Helicobacter pylori has yet to be ascertained, as well as its source. Presently, the only recognized and accepted reservoir is the human stomach, but the existence of extra-gastric reservoirs for Helicobacter pylori has been suggested. The prevalence of infection is especially higher in the rural developing areas in contrast to urban developed ones. In addtion, the prevalence of infection is typically higher in developing countries (greater than 80%) and lower in the developed ones (typically less than 40%) with a declining pattern worldwide. Globalization and the rapid mobility of the population may disturb in the near future the six large clusters of Helicobacter pylori strains currently spread throughout the world. The authors reviewed and discussed the possibility of the transmission of Helicobacter pylori by food and water in developed and developing countries.

Reference

The article appears in the March 2010 issue of the International Journal of Food Microbiology (volume138, issues 1-2, pages 1-12). Authors: F.F. Vale & J.M.B. Vítor.

Abstract

Helicobacter pylori is a Gram-negative microaerophilic bacterium that has colonized the human gastric mucosa. This infection is very common and affects more than half of the human population. The prevalence is however unbalanced between rural developing areas (more than 80%) and urban developed areas (less than 40%). H. pylori is responsible for several pathologies, such as gastritis, peptic ulcer and gastric cancer but its transmission pathway is still not clear. The risk factors for H. pylori infection include poor social and economic development; poor hygienic practices; absence of hygienic drinking water; and unsanitary prepared food. There is evidence supporting a gastro–oral, oral–oral and faecal–oral transmission, but no predominant mechanism of transmission has been yet identified. Transmission may occur in a vertical mode (e.g. from parents to child) or in a horizontal mode (across individuals or from environmental contamination). In either case, the involvement of water and food cannot be excluded as vehicles or sources of infection. Indirect evidence of presence of H. pylori in water and food, namely the detection of its DNA and survival studies after artificial contamination of food and water has been described. This paper reviews data both favourable and against the role of water and food in the transmission of H. pylori, exploring their role as a potential transmission vehicle for person-to-person and food-chain transmission. The likelihood of the transmission pathway in developing rural and developed urban areas appears to be different. In developed areas, person-to-person transmission within families appears to be dominant, while in the rural developing areas the transmission pathway appears to be more complex. In this later case, the transmission by contaminated food, water, or via intensive contact between infants and non-parental caretakers may have a greater influence than within-family transmission.