ABO blood groups and smallpox in a rural population of West Bengal and Bihar (India).

Abstract

The problem was reexamined whether there is a relationship between the AB0 blood groups and incidence, severity and outcome of smallpox. In persons suffering from smallpox, and living in rural areas of West Bengal and Bihar, India, severity and outcome of the disease were registered, and the AB0 blood groups were determined. Healthy siblings were used as controls for incidence. Four series were available: Relative incidence of smallpox was shown to the much higher in suffering patients of groups A and AB, when compared with the healthy siblings (x=6.09; χ2 (DF=1)=128.92). Within the patient group, severe forms and fatal outcome were significantly more frequent in groups A and AB as compared with groups B and 0. The surviving cases showed a much higher frequency of groups B and 0 than the fresh cases of the same area, indicating a much higher mortality of A and AB persons also in these series. Within the group of survivors, severe smallpox scars were significantly more frequent in groups A and AB. The combined results of an examination of 986 smallpox patients and 778 controls gave conclusive evidence in favour of a strong disadvantage of groups A and AB towards the smallpox infection. However, as comparison with other series shows, the influence of the blood group seems to be confined to severe manifestations in unvaccinated persons who are living under natural, primitive conditions without medical care. Some immunological implications of the result are discussed.