Laboratory markers of disease severity in Plasmodium knowlesi infection: a case control study

This study was funded by the Medical Research Council (MRC) UK; Grant number G0801971, and the London School of Hygiene and Tropical Medicine (Trust Funds award)Background: Plasmodium knowlesi malaria causes severe disease in up to 10% of cases in Malaysian Borneo and has a mortality rate of 1 - 2%. However, laboratory markers with the ability to identify patients at risk of developing complications have not yet been assessed as they have for other species of Plasmodium. Methods: A case control study was undertaken in two hospitals in Sarikei and Sibu, Malaysian Borneo. One hundred and ten patients with uncomplicated (n = 93) and severe (n = 17) P. knowlesi malaria were studied. Standardized pigment-containing neutrophil (PCN) count, parasite density and platelet counts were determined and analysed by logistic regression and receiver operating characteristic (ROC) analysis. Results: The PCN count was strongly associated with risk of disease severity. Patients with high parasite density (>= 35,000/mu l) or with thrombocytopaenia (= 35,000/mu l or >= 1% or a platelet count <= 45,000/mu l can be regarded at risk of developing complications and should be managed according to current WHO guidelines for the treatment of severe malaria.Publisher PDFPeer reviewe