White blood cells counts and parasite density in malaria in children aged 6 to 60 months in urban areas of Togo

Abstract

Rational use of the artemisinin-based combination therapies in Togo requires laboratory parasitemia values to confirm suspected malaria. This study was conducted to determine the impact of the measured white blood cell (WBC) count on the determination of malaria parasite density among children younger than 5 years old infected with uncomplicated Plasmodium falciparum in Togo. This cross-sectional study of 267 children from four pediatric centers diagnosed malaria with both thick and thin blood smears and counted WBCs with a hematology analyzer. The parasite densities, calculated with the number of WBCs and estimated with an assumed count of 8,000/μL, were compared with the Wilcoxon matched pairs signed-rank test. The children's median age was 35 months (interquartile range [24-48]), with a sex ratio of 1.32. The median WBC value was 8,300 cells/μL (range: 1,300-24,900 cells/μL). The median parasitemia value calculated with the absolute WBC count was 35,714 (range: 139-48,860 parasites/μL) was not statistically different from that estimated with the assumed value of 8,000 cells/μL -33125 parasites/μL (p=0.564). This study shows that malaria parasite density obtained by assuming 8000 cells/μL does not result in overestimations for children aged 6-59 months.