The presence of malaria pigment within neutrophils and monocytes is a prognostic marker for patients with Plasmodium falciparum infection. This can help identify patients with severe malaria who have an increased risk of death.
Measures of intraleukocytic malaria pigment:
(1) percent neutrophils and monocytes with cytoplasmic pigment
(2) absolute count of neutrophils and monocytes with cytoplasmic pigment
percent neutrophils with cytoplasmic pigment =
= (number of neutrophils with cytoplasmic pigment) / (number of neutrophils counted) * 100%
total number pigmented neutrophils with cytoplasmic pigment per µL =
= (percent neutrophils with cytoplasmic pigment) * (WBC count per µL) * (percent neutrophils in differential count of peripheral blood)
total number pigmented monocytes with cytoplasmic pigment per µL =
= (percent monocytes with cytoplasmic pigment) * (WBC count per µL) * (percent monocytes in differential count of peripheral blood)
where:
• If the percent of monocytes with pigment was > 0 and < 1% then a value of 0.5% was used by Lyke et al. I did not do this in the implementation.
According to Phu et al, a percent neutrophils with cytoplasmic pigment >= 5% was associated with a fatal outcome with a sensitivity of 73% and specificity of 77%.
According to Lyke et al, an absolute pigment laden neutrophil count > 324 per µL was associated with cerebral malaria in children in Mali (Table 4, page 258).
