PLASMODIUM-FALCIPARUM GAMETOCYTEMIA IN KENYAN CHILDREN - ASSOCIATIONSAMONG AGE, INTENSITY OF EXPOSURE TO TRANSMISSION, AND PREVALENCE AND DENSITY OF SUBSEQUENT GAMETOCYTEMIA

Recently, an association was described between the density of Plasmodi um falciparum asexual parasitemia in Kenyan children and the entomolog ic inoculation rate (EIR) measured prior to measurement of asexual par asitemia. This study examined whether transmission pressure, as repres ented by the EIR, was associated with the prevalence or density of gam etocytemia in Kenyan children. Each month for 19 months, a cohort of a pproximately 50 children was given a radical cure and enrolled in the study. Blood films were taken on days 0, 7, and 14. The EIR was calcul ated for the 28-day period ending 14 days prior to enrollment: the rel ationship between blood film data from day 7 and exposure variables wa s explored. We found that younger children were more likely to be game tocytemic than older children and, if gametocytemic, were mon likely t o have a dense gametocytemia. There was an inverse relationship betwee n the number of infective bites per night received and prevalence but not density of gametocytemia, even after age adjustment. Concordance o f gametocytemia prevalence on days 0 (64%), 7 (66%), and 14 (52%) was poor; 84% of the children were positive on at least one day. This indi cates that in many subjects the detectable gametocytemia varied over t he 14 days. Under these holoendemic transmission conditions, the EIR i s inversely correlated with prevalence of gametocytemia, and point mea surements of gametocytemia by conventional microscopy underestimate th e number of infective donor hosts.