Longitudinal cohort study of the epidemiology of malaria infections in an area of intense malaria transmission II. Descriptive epidemiology of malaria infection and disease among children

A large-scale longitudinal cohort project was initiated in western Kenya in June 1992. Between June 1992 and July 1994, 1,848 children less than 15 ye ars of age were monitored prospectively for a mean of 236 days. During this period, 12,035 blood smears were examined for malaria and only 34% were fo und to be negative. Parasite prevalence (all species) decreased with age (f rom a high of 83% among children 1-4 years old to 60% among children 10-14 years old). Even more dramatic decreases were noted in the prevalence of hi gh density falciparum infection (from 37% among children 12-23 months old t o <1% among 10-14-year-old children) and in clinical malaria (20% to 0.3% i n the same age groups). Children <1 year of age accounted for 55% of all ca ses of anemia detected. Anemia was consistently associated with high densit y infection in children <10 years of age (20% to 210% increased risk relati ve to aparasitemic children). These results demonstrate the relationship be tween high-density malaria infection and two clinical manifestations of mal arial illness.