Helicobacter pylori infection in children.

Helicobacter pylori colonises the stomach of man, especially during childhood. However, Helicobacter pylori strains are not created equal, with major differences in virulence characteristics which probably account for different clinical symptoms. The majority of infected subjects remain asymptomatic. H. pylori infection is correlated with socioeconomic conditions and hygienic circumstances, resulting in an extremely high prevalence in (children of) developing countries. Commercial available screening tests are not capable to separate the more virulent strains (type I with vacuolating toxin VacA and CagA protein) from the less virulent strains (Type II, vacA and CagA negative). Type I strains, but not Type II, are associated with an increased risk for duodenal ulcer and gastric cancer. Therefore, (future) screening tests (and vaccination) should focus on the Type I strains.