HP and malaria: Haptoglobin was lower in patients with severe and non-severe knowlesi malaria compared to controls (0.11 g/dL, 0.30 g/dL, and 1.44 g/dL, respectively, p < 0.0001 for both comparisons), and lower in patients with severe compared to non-severe knowlesi malaria (p = 0.004).