EVIDENCE FOR ETHNIC TROPISM OF HELICOBACTER-PYLORI

Helicobacter pylori infection in humans is linked to gastritis, gastri c and duodenal ulcers, and gastric cancer, Peptic ulcer disease, as di stinct from chronic asymptomatic infection, is strongly associated wit h expression of bacterial virulence markers, including a major antigen , CagA, and the vacuolating cytotoxin VacA. We have previously describ ed significant differences in colonization rates, independent of socio economic status, among ethnic groups in New Zealand, To evaluate relat ive risks for peptic ulcer disease, we examined the frequency of two v irulence markers in H. pylori strains infecting these ethnic groups, A lthough these markers occurred significantly more frequently in strain s isolated from Polynesians than in strains from Europeans, this frequ ency was not reflected in the incidence of peptic ulcer disease in the two groups, DNA fingerprinting of the urease gene showed that Polynes ians are more frequently infected by a group of strains which are gene tically distinct from those affecting European New Zealanders, Our dat a suggest that separate bacterial lineages may have evolved in paralle l with race-specific specialization.