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Researchers at the Worldwide Antimalarial Resistance Network (WWARN), hosted by NDM’s Centre for Tropical Medicine and Global Health, investigated the variability in white blood cell count in patients with uncomplicated malaria and found that using the assumed value of WBC in the calculation of parasite density led to a significant underestimation of parasite count for children and potentially sub-optimal treatment.

© Dominic Chavez, World Bank

This paper published in the BMC journal is the first Individual patient data meta-analysis to characterise WBC count levels in both P. falciparum and P. vivax malaria across a range of endemic settings. An uncomplicated malaria is a form of malaria that does not have any severe symptoms.

Researchers at WWARN reviewed WBC counts during acute uncomplicated malaria in 27,656 patients from 84 studies across Africa, Asia-Pacific and the Americas. WBC counts are needed in the calculation of parasite density when thick smear microscopy is used, however, in resource-limited settings an assumed WBC is often used instead.

This study explored the implications of this practice. First, researchers confirmed that assuming a WBC count of 8000 cells/µL did not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance. However, the study showed that using the assumed value of WBC count of 8000 cells/ microlitre resulted in a significant underestimation of parasite counts in children, which could lead to the sub-optimal treatment of children with clinically uncomplicated but hyperparasitaemic malaria.

A hyperparasitaemic malaria is a severe form of malaria that is characterized by an abnormally high number of malaria parasites in the blood. Patients with hyperparasitaemia, even if clinically uncomplicated, are more likely to experience initial failure of their treatment or a recrudescence of malaria with a conventional 3 days artemisinin combination therapy.

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