Estimating malaria parasite density using actual and assumed white blood cells in Ugandan patients in Tororo district

Abstract

White blood cell count plays a major role in the estimation of malaria parasitemia densities therefore it has been recommended by WHO to estimate using the assumed count of 8000cells/ μL due to lack of facilities in the endemic areas. Data was analyzed from 125 participants who consented to participate in the study. Whole blood was collected and used to make thick smears. The blood sample was also analysed using an automated hematology analyzer for the individual WBC counts later used to estimate the parasite densities which were compared against densities using the assumed count of 8000/ μL. Blood smears were read by two independent readers and averages calculated by a neutral laboratory technician. With the mean age of the participants in the study being 16.48 years, mean of actual WBC count was 6228.48/ μL lower than the assumed 8000/ μL recommended by WHO. Mean of assumed parasite density was 21506.62 parasites/ μL slightly higher than 19920.06 parasites/ μL mean parasite density using actual WBC counts. The difference is also represented in the geometric means of assumed and actual densities respectively; 8546.251 (6441.543-11338.65) and 5978.628 (4393.275-8136.071). There was no significant difference in the parasite densities of participants under 12 years using assumed or actual patient WBC count but for participants above 12 years there was a significant difference in the parasitemia densities with p-value of 0.0037. Therefore, this study recommends use of patient’s actual WBC count when determining parasite density for individuals above 12 years of age and those below 12 years assumed WBC counts can be used.