Familial clustering of Helicobacter pylori infection: population based study

Objectives To assess the rate of intrafamilial transmission of Helicobacter pylori infection in the general population and the role of a family's soci al background. Design Population survey. Setting Campogalliano, a town in northern Italy with about 5000 residents. Participants 3289 residents, accounting for 416 families. Main outcome measures Prevalence of H pylori infection assessed by presence of IgG antibodies to H pylori. Results The overall prevalence of H pylori infection was 58%. Children belo nging to families with both parents infected had a significantly higher pre valence of H pylori infection (44%) than children from families with only o ne (30%) or no parents (21%) infected (P < 0.001). Multivariate analyses co nfirmed that children with both parents positive had double the risk of bei ng infected by H pylori than those from families in which both parents were negative. Family social status was independently related to infection in c hildren, with those from blue collar or farming families showing an increas ed risk of infection compared with children of white collars workers (odds ratio 2.02, 95% confidence interval 1.16 to 3.49). Conclusions H pylori infection clusters within families belonging to the sa me population. Social status may also be a risk factor. This suggests eithe r a person to person transmission or a common source of exposure for H pylo ri infection.