Abstract
**Background:**
Plasmodium falciparum pigment-containing leucocytes (PCLs) have been identified as markers associated with adverse clinical manifestations of severe malaria in African children. However, there is a paucity of data regarding the presence and impact of PCLs in regions outside of Africa.
**Methods:**
Peripheral blood slides from children aged 6 months to 10 years diagnosed with severe malaria were subjected to examination for the presence of PCLs. Correlation analysis was conducted between intraleucocytic pigment data and clinical phenotypic factors such as severe anaemia, metabolic acidosis, and coma to elucidate the association of PCLs with the clinical manifestations of severe malaria and patient outcomes.
**Results:**
Out of the 169 children diagnosed with severe P. falciparum malaria confirmed by microscopy, 76% (129/169) exhibited PCLs.
Compared with children devoid of PCLs, those with the presence of pigment-containing monocytes (PCMs) showed a significantly increased likelihood of severe anaemia (adjusted odds ratio [AOR] 3.2 [95% confidence interval {CI} 1.5 to 6.9], p≤0.01). Additionally, the quantity of PCMs (AOR 1.0 [95% CI 1.0 to 1.1], p=0.04) was significantly associated with severe anaemia. The quantity of both PCMs (AOR 1.0 [95% CI 1.0 to 1.1], p≤0.01) and pigment-containing neutrophils (AOR 1.0 [95% CI 1.0 to 1.1], p=0.01) exhibited a significant association with metabolic acidosis. Plasma P. falciparum histidine-rich protein-2 levels demonstrated a negative correlation with platelet count (r=−0.5, p≤0.01) in patients with both PCLs and no PCLs.
**Conclusions:**
In Papua New Guinean children experiencing severe P. falciparum malaria, the presence and quantity of PCLs serve as predictive indicators of disease severity, particularly in relation to severe anaemia and metabolic acidosis.