SadoMacho
spanker of civilizations
Not a difference between rich and poor, but a rich provence often didn't get the Plague because the people were beter feed and stronger, so more resistent against illnesses, and also the Plague.
( nobody expects the Spanish... flu?)
CCR5-Δ32 (or CCR5-D32) is a genetic defect affecting the human immune system that has both harmful and beneficial effects. It is a deletion mutation of a gene specifically impacting the function of T cells. CCR5-D32 is widely dispersed throughout Northern Europe and in those of European descent. It has been hypothesized that this allele was favored by natural selection during the Black Death, or during smallpox outbreaks, which is, however, unlikely, given that the frequency of CCR5-Δ32 in Bronze Age samples is similar to that seen today.[1] The allele has a negative effect upon T cell function, but appears to protect against smallpox, plague and HIV. Individuals with the Δ32 allele of CCR5 are healthy, suggesting that CCR5 is largely dispensable. However, CCR5 plays a role in mediating resistance to West Nile Virus infection in humans, as CCR5Δ32 individuals are enriched in cohorts of West Nile Virus symptomatic patients, indicating that all of the functions of CCR5 may not be compensated by other receptors.
While CCR5 has multiple variants in its coding region, the deletion of a 32-bp segment results in a nonfunctional receptor, thus preventing HIV R5 entry; two copies of this allele provide strong protection against HIV infection, although the protection is not absolute. [2] This allele is found in up to 20% of Europeans but is rare in Africans and Asians. Multiple studies of HIV-infected persons have shown that presence of one copy of this allele delays progression to the condition of AIDS by about 2 years. It is possible that a person with the CCR5-Δ32 receptor allele will not be infected with HIV R5 strains.