Community-based familial study of Helicobacter pylori infection among healthy Japanese Brazilians

Background. The present study of Helicobacter pylori infection was conducted in family units of Japanese Brazilians living in São Paulo city. The authors attempted to determine the seroprevalence of H. pylori infection within family units of Japanese Brazilians and to identify risk factors associated with intrafamilial transmission. Methods. The seroprevalence was determined in 1037 healthy and asymptomatic volunteer subjects aged 0-69 years (530 adults and 507 children) of 265 families. Demographic data and details of living conditions were obtained from each family. Results. H. pylori seropositive infection was found in 39.2% of the parents and 9.3% of the children. A reduced risk of H. pylori infection was found for girls (odds ratio [OR] 0.45; 95% confidence interval [CI], 0.23-0.86). The prevalence of infection was 3.5% for children with uninfected parents; 9.9% (OR, 2.51; 95% CI, 0.95-6.61) for those with a seronegative mother and a seropositive father; 14.9% (OR, 4.93; 95% CI, 1.86-13.06) for those with a seropositive mother and a seronegative father; and 16.0% (OR, 5.29; 95% CI, 1.98-14.14) for those with seropositive parents. On multivariate analysis, the use of a pacifier, and mother's symptoms of nausea and vomiting were significantly associated with the risk of H. pylori infection for children, and the child having her/his own room was significantly associated with a reduced risk. Income was not associated with H. pylori infection in children and was inversely associated in parents. Conclusion. The prevalence of H. pylori infection in family units of Japanese Brazilians supports the hypothesis of a predominant role for mother-child transmission of H. pylori infection, mainly through contact with regurgitated gastric juice in the mother's mouth. © 2006 by International and Japanese Gastric Cancer Associations.