ABO, Rh, MNSs, sex and typhoid fever.

A case-control study on the association between genetic markers (ABO, Rh, MNSs and sex) and typhoid fever (TF) was performed. We found that (a) the B allele conferred protection to females for TF and a mild susceptibility to males; (b) the CDe haplotype (or the RH3 phenotype, mostly CDe/CDe) was associated with protection against Salmonella in both sexes, while cDE (or RH7, mostly cDE/cDE, and RH8, mostly cDE/cde) was associated with susceptibility to TF, and (c) heterozygotes Ss (MNSs system) had a high susceptibility, while SS and particularly ss homozygotes seemed to be protected for the disease. There were very significant interactions among the blood systems and sex.