Parental smoking and infection with Helicobacter pylori among preschool children in southern Germany.

Exposure to parental smoking is known to increase children's susceptibility to a variety of infections. We investigated the relation of parental smoking to infection with Helicobacter pylori in a population-based study among preschool children who were screened for school fitness in the city of Ulm, Germany, in 1996. Current infection with H. pylori was measured by a 13C-labeled urea breath test. Information on factors potentially related to H. pylori infection, including parental smoking in the household, was obtained from children's parents through a self-administered standardized questionnaire. Among 1,201 eligible children, 945 participated in the study (response rate = 79%). Overall prevalence of active infection was 13.7%. After adjustment for confounding factors, we found a strong positive relation between smoking by the father in the household and H. pylori infection (odds ratio = 3.7; 95% confidence interval = 2.3-6.1). By contrast, there was a strong negative relation between smoking by the mother and H. pylori infection (odds ratio = 0.4; 95% confidence interval = 0.2-0.8) that was most pronounced among children who had been breastfed. These striking patterns cannot be explained by current knowledge.