The prevalence of red-cell antigens and antibodies in Malawi.

As there were no reliable data in Malawi for the prevalence of red cell alloantibodies or antigens in the population, a study was conducted to screen 1000 patients for the presence of antibodies and to type them for ABO, RhD, C, c, E, e and K antigens and to test 500 donors for these antigens plus Fy(a), Fy(b), Jk(a), Jk(b), S and s. Red cell antibodies were identified in 11 patients [1.1%]; 2 were anti-D, 2 anti-S, 1 anti-Le(a+b) and 6 anti-M, 4 of which were found in non-transfused males suggesting they might be naturally acquired. The antigen frequencies found were similar to those previously published for Central Africa but 98.2% of donors were found to be Fy(a-b-). All patients tested were K negative and only three donors were found to be K positive, one being a Caucasian. Approximately 3.5% of Malawians are D negative, lower than the usual 8% quoted for Black Africans. These data confirm the assumption that pre-transfusion antibody screening is not currently required but that use of the indirect antiglobulin test in the cross-match is necessary. Haemolytic disease of the newborn (HDN) appears to be rare, or under reported, in Malawi, and more work is needed to find the real incidence of this condition.