High prevalence of potentially virulent strains of Helicobacter pylori in the general male British population

Background-Strains of Helicobacter pylori that express the cytotoxin associ ated gene product A (CagA) may be more strongly associated with serious gas tric diseases, such as gastric cancer and peptic ulceration, than other str ains. Data, however, are sparse on the prevalence, risk factors, and other correlates of these strains in the general population. Aim-To characterise aspects of the seroepidemiology of CagA(+) strains of H pylori in the general British population. Methods-We measured serum IgG an tibodies to mixed H pylori antigens and separately to CagA in 1025 men aged 40-59 years who were randomly selected from a larger group of participants in a community based survey conducted in 18 different British towns. Results-Overall, 44% (95% confidence interval 41-47%) of the men were serop ositive to CagA antibodies, representing about 61% (57-65%) of the men sero positive to mixed antigen H pylori. The risk factors for seropositivity to CagA antibodies were similar to those for seropositivity to mixed antigen H pylori, apart from an increased prevalence of reported bedroom sharing in childhood (p<0.01). Conclusion-In a nationwide study of potentially virulent H pylori strains, there was a high prevalence of the infection, with some evidence that acqui sition of such strains might occur earlier in life than other strains.