Helicobacter pylori prevalence and transmission among children attending rural schools: a critical review of evidence

Helicobacter pylori is a micro-aerophilic, Gram-negative bacterium that colonizes the human stomach, leading to gastritis, peptic ulcer, among other diseases. The estimated world prevalence of H. pylori is about 50% for adults and 35% for children, but this prevalence of infection is rather unbalanced, depending on local conditions. For developed areas, there is a clear trend towards a decrease in prevalence rate, whereas in developing areas, mainly rural ones, a high prevalence rate (more than 80%) persists. Despite significant scientific research efforts, the transmission of H. pylori pathway is still not clearly defined. Possible transmission routes involve vertical (e.g. from parents to child) or horizontal (across individuals or from environmental contamination) transmission. In developed urban environments, the molecular typing of H. pylori strains points to a person-to-person transmission, mainly between family members. However, in developing rural areas, the transmission appears to be more complex, involving intense contact between children and adults other than family members, as well as ingestion of contaminated food and water. H. pylori infection occurs mainly during childhood, which makes children the principal age group population at risk. Several risk factors for infection have been identified, such as poor social and economic conditions, low education levels, poor hygiene practices during childhood, crowded households, absence of sanitary drinking water and of a sewage disposal facility during childhood, among other causes. The present chapter reviews the evidence of prevalence and transmission routes in children attending rural schools. Prevalence data on H. pylori infection in children for several countries for the last five years (2005 to 2009) that is available in Pubmed is gathered. This data is then correlated with sanitation level and safety of drinking water sources specific for each country. Preventive measures to avoid H. pylori dissemination among children attending rural school are discussed.