Background. There exist only inconsistent results of studies on the relationship between Helicobacter pylori (H. pylori) infection and functional dyspepsia and/or recurrent abdominal pain in children and adolescents. The answer could bring a comparison of the epidemiological features of H. pylori infection between children and adolescents with dyspepsia and/or recurrent abdominal pain (symptomatic) and without these symptoms (asymptomatic), living in the Czech republic. Methods and Results. Study includes children and adolescents (2–18 years) with upper gastrointestinal symptoms visiting paediatric gastroenterology department between 1994 and 1999. Age, sex, socioeconomic level matched control (asymptomatic) group consisted of children and adolescents visiting the general paediatric service with symptoms not related to the upper gastrointestinal tract.Demographic and socioeconomic factors, including parent(s) educational level, place of residence, living conditions, type of drinking water and pets in their household were evaluated. Serum of the children and adolescents was tested for H. pylori IgG by enzyme linked immunosorbent assay. In addition, the symptomatic children and adolescents underwent endoscopic examination and biopsies from gastric antrum and corpus were taken for the quick urease test, histology/histoscopy, and H. pylori cultivation. H. pylori infection in this group was stated when at least two testswere positive.Altogether 829 children and adolescents were examined, 624 cases were symptomatic and 205 represented controls (asymptomatic). The prevalence of infection was 33 % among symptomatic children vs. 7,5 % among controls (OR = 6.2, p.001) and was similar among boys and girls (32 % vs. 34,5 %, respectively). H. pylori prevalence increased with age among symptomatic children (10 % for children below 6 years and 37 % between 11 to 16 years) (p.001). In contrary, prevalence tended to fall with age among asymptomatic children (11% in children below 6 years vs. 6 % in children over 10 years (OR=2.0, 95 % CI=0.7-6.2). In both groups, an inverse correlation between H. pylori occurrence and mother’s educational levelwas observed. The H. pylori incidence was 10%among asymptomatic childrenwho drank water frommunicipal water supply or from a well vs. 3% among those who drank bottled water (OR=4, 95 % CI = 1.1 to 18, p.05). Conclusions. H. pylori infection was more prevalent among symptomatic children and adolescents vs. asymptomatic children and adolescents within the same population. H. pylori incidence increased with age among symptomatic children and adolescents and tended to fall among controls, showing deep differences between the two groups.With exception of the bottled water drinking, presence of any other factor studied represented significant risk for acquiring the H. pylori infection.

        Key words: Helicobacter pylori infection, epidemiology, symptomatic, asymptomatic, children, adolescents. Se.