The relationship of American visceral leishmaniasis to ABO blood group type.

It has been hypothesized that the Leishmania use a system of camouflage or mimicry of human ABO blood group antigens to evade host defense mechanisms. In order to test this hypothesis, the distribution of ABO blood groups among healthy control donors and among patients with visceral leishmaniasis in northeastern Brazil was compared. No significant differences were found between patients with American visceral leishmaniasis and controls, indicating that ABO blood group type is not an important determinant in the development of clinically apparent visceral leishmaniasis in that area. The findings raise doubt about the validity of the original hypothesis.