Allelic Diversity of the Helicobacter pylori Vacuolating Cytotoxin Gene in South Africa: Rarity of the vacA s1a Genotype and Natural Occurrence of an s2/m1 Allele

We describe the rarity of Helicobacter pylori strains of vacuolating cytotoxin type s1a (the type most commonly associated with peptic ulceration in the United States) among black and mixed-race South Africans. We also provide the first description of a naturally occurring strain with the vacA allelic structure s2/m1.