PCT levels before treatment in patients with tertian malaria (triangles) compared to falciparum malaria (open squares: survivors; filled squares: patients that died). Cluster A: semi-immune patients; cluster B: non-immune patients with mild disease; cluster C: non-immune patients with severe and complicated disease. The horizontal line at 2.5 ng/ml is the lower cut-off for complicated falciparum malaria and arbitrarily discriminates a high level from a low level group in tertian malaria. Falciparum malaria data originate from another study).).