Malarial antibodies in Auckland blood donors.

AIM: To determine the malarial exposure characteristics of "malarial risk" blood donors and measure the potential infectivity of their donations using a commercially available malarial antibody screening kit. METHOD: Malarial risk donors were identified according to standard protocols, questioned as to their degree of exposure to malaria and blood samples were tested for malarial antibodies using an enzyme immunoassay kit. The kit used detects IgG antibodies to P. falciparum, shows 50% crossreactivity with P. vivax and some crossreactivity with P. ovale. Antibody positive samples were further checked by a direct immunochromatographic test for P. falciparum. RESULTS: We found 1.7% of the donors who were classified as a "malarial risk" to be positive for IgG malarial antibodies. None of these antibody positive samples was positive by the direct immunochromatographic test for P. falciparum. CONCLUSION: These results indicate that none of these donors tested were a risk of transmitting P. falciparum, the major and most serious cause of transfusion transmitted malaria. The introduction of malarial testing of malarial risk blood donors in Auckland, currently deferred for plasma donation only, could potentially recover 2300 units of red cells per year.