AGE-DEPENDENT SUSCEPTIBILITY TO SEVERE DISEASE WITH PRIMARY EXPOSURE TO PLASMODIUM-FALCIPARUM

This study investigated the incidence of severe disease following prim ary exposure to Plasmodium falciparum by nonimmune children and adults in Irian Jaya, Indonesia. Four months after arrival, the cross-sectio nal prevalence of P, falciparum was 72%, and the monthly cumulative in cidence of clinical diagnoses of malaria was 81%. Delirium or unconsci ousness prompted evacuation to the hospital. Records of emergency evac uation of persons with a clinical diagnosis of malaria revealed an inc idence density among adults (>15 years) of 1.34 events/person-year in the third month, whereas the rate in children remained stable at simil ar to 0.25 events/person-year (relative risk = 4.51, 95% confidence in terval [CI] = 1.94-11), Through the first 6 months of exposure, 23.2% of adults were evacuated to the hospital with a diagnosis of malaria c ompared with 8.6% of children (relative risk = 2.7, 95% CI = 1.9-3.8). In this population with relatively few infants or people of advanced age, the risk of severe disease following primary exposure to P. falci parum increased with age.