ASSESSMENT OF AGE-DEPENDENT IMMUNITY TO MALARIA IN TRANSMIGRANTS

Sixty-six Javanese transmigrants moving from Java, an area of very low malaria transmission, to Irian Jaya, an area of high malaria transmis sion, were monitored to evaluate the effects of exposure to malaria tr ansmission and age on resistance to infection and the induction of hum oral immunity. The risk of acquiring Plasmodium falciparum parasitemia was not statistically greater in children (5-15 years of age) than in adults (> 15 years of age) during the first 14 months of exposure. Ho wever, during the cross-sectional survey at 14 months of exposure, chi ldren did have significantly higher P. falciparum asexual blood-stage parasite densities. Serum antibody titers to R32LR, a peptide containi ng sequences from the P. falciparum circumsporozoite repeat region, an d MSP19, a proteolytic fragment of merozoite surface protein-1 (MSP-1) from P. falciparum, were measured by enzyme-linked immunosorbent assa y. Exposure for both six and 14 months produced statistically signific ant increased antibody titers to both R32LR and MSP-1; no age-dependen t difference in antibody titers was observed. In this population, expo sure to malaria transmission induced antibodies to antigens associated with immunity to malaria. In addition, we noted an age-dependent diff erence in the parasitemia density of P. falciparum.