Procalcitonin serum levels in tertian malaria

Abstract

Background: Procalcitonin (PCT) is closely correlated with parasite burden and clinical outcome in falciparum malaria. The role of PCT in tertian malaria has not previously been investigated.

Patients and methods: PCT serum levels in 37 patients with tertian malaria were analysed. Clinical and laboratory parameters were assessed and statistically correlated both to the initial PCT levels and during the course of the disease.

Results: PCT levels rose for one day after commencing treatment and declined thereafter. However, there was no significant correlation with parasite burden, clinical parameters, laboratory values, or the presence of semi-immunity. Before treatment, the majority of patients showed normal or slightly elevated PCT levels (< 2.5 ng/ml), but PCT was markedly elevated (4.8-47 ng/ml) in one third of the population. The two groups did not differ by any other of the assessed parameters. Thus, while the post-treatment course of PCT resembles falciparum malaria, the lack of correlation between disease severity and even high PCT levels in a large proportion of patients is intriguing.

Conclusions: There is a fundamental difference in the relationship of PCT with tertian malaria not seen in other infectious diseases in which elevated PCT levels have been observed. This suggests distinct pathophysiological pathways in malaria.

Figure 1

Serum procalcitonin (PCT) concentrations in 37 patients with tertian malaria immediately before treatment (day 0), and on follow-up. Box: median, 25^th, and 75^th percentile; whiskers: 5^th and 95^th percentile; star: 1^st and 99^th percentile; open squares: mean; filled circles: geometric mean.

Figure 2

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).)[5].