Multiple strains of Plasmodium falciparum are necessary for the growth inhibition assay.

Sixty-seven serum samples from individuals living in a malaria endemic area and sixty sera from healthy blood donors living in Bangkok (non-malarious area) were tested for growth inhibition activity against 3 strains (SO, SN and G-112) of Plasmodium falciparum. Forty-eight percent of the sera from the endemic area were positive when all 3 strains were tested. Among the positive sera, positive rates of 90.6% were observed for the SO and SN strain combination, 87.5% for the SO and G-112 combination, and 50% for the SN and G-112 combination. It is therefore recommended that multiple parasite strains should be tested in the growth inhibition assay. If facilities are limited, a minimum of two strains should be used, one of which is the SO strain or its equivalent.