Comparative analysis of malaria parasite density using actual and assumed white blood cell counts.

AIM

To compare malaria parasite densities, calculated using the white cell counts (WBC) of individual children with a standard WBC count of 8.0 x 10(9)/L.

METHODS

In a cross-sectional study, the prevalence of malaria WBCs and malaria parasite densities were estimated in 240 healthy Nigerian children aged 1-8 years.

RESULTS

Of 240 children, 75 (31.25%) were infected with malaria, 69 (28.75%) with P. falciparum and 9 (3.75%) with other species. The mean (SD) WBC count was 5.1 (2.0) x 10(9)/L. There was an age-related significant difference in the mean WBC counts (t=2.000, p<0.05), with values higher in the under-5s [5.6 (2.0) x 10(9)/L] than in the > or =5-years group [5.0 (1.8) x 10(9)/L]. No significant difference was observed with regard to gender and malaria infection. The mean (SD) parasite densities of P. falciparum obtained using the assumed value of 8.0 x 10(9)/L [1936 (1119.5)] was significantly higher than the parasite densities estimated using the individual WBC counts [1140 (862.8) for P. falciparum] (p<0.0001).

CONCLUSION

Parasite density estimation using the assumed count of 8.0 x 10(9)/L might result in over-estimation of the parasite burden. The WBCs of individual patients should always be estimated when parasite density is required.