Effect of Plasmodium falciparum parasitemia density on hemoglobin concentrations among full-term, normal birth weight children in western Kenya, IV. The Asembo Bay Cohort Project

The relative importance of acute high-density versus persistent low-density Plasmodium falciparum parasitemia in contributing to the public health pro blem of malarial anemia remains unclear. The Asembo Bay Cohort Project in w estern Kenya collected monthly hemoglobin (Hb) and parasitologic measuremen ts and biweekly assessments of antimalarial drug use among 942 singleton li ve births between 1992 and 1996. A mixed-model analysis appropriate for rep eated measures data was used to study how time-varying parasitemia and anti malarial drug exposures influenced mean Hb profiles. Incidence of World Hea lth Organization-defined severe malarial anemia was 28.1 per 1,000 person-y ears. Among children aged less than 24 months, concurrent parasitemia was s ignificantly associated with lower mean Hb, especially when compared to chi ldren with no concurrent parasitemia. Increased densities of the 90-day his tory of parasitemia preceding Hb measurement was more strongly associated w ith mean Hb levels than concurrent parasitemia density. While the highest q uartile of 90-day parasitemia history was associated with lowest mean Hb le vels, children in the lowest 90-day exposure quartile still experienced sig nificantly lower Hb levels when compared to children who remained parasitem ia-free for the same 90-day period. The results highlight the importance of collecting and analyzing longitudinal Hb and parasitologic data when study ing the natural history of malarial anemia.