Purpose: Prospective data on potential factors associated with severity of imported Plasmodium falciparum malaria are lacking. We evaluated whether several host- and parasite-related biomarkers may improve early severity evaluation.

Methods: Prospective multicenter observational study comparing uncomplicated and severe imported falciparum malaria in adults conducted in France in 52 units, from 2007 to 2010. Association of several host- and parasite-related biomarkers with severity of malaria was tested using univariate and multivariate analyses.

Results: Of 295 patients, 140 had uncomplicated malaria and 155 severe malaria (including very severe and less severe cases according to predefined criteria). Curative intravenous quinine treatment was used in 154/155 patients with severe malaria and atovaquone/proguanil in 74 % of patients with uncomplicated malaria. Hospital mortality was 5.2 % (8 patients), all in the severe malaria group. Among host-related biomarkers, CRP, procalcitonin, and sTREM-1 were significantly higher and albumin was significantly lower in severe versus uncomplicated malaria; only the last three biomarkers also differed significantly between the very and less severe malaria groups. Among parasite-related biomarkers, only plasma PfHRP2 was significantly higher in severe versus uncomplicated malaria and in very severe versus less severe malaria; parasitemia did not differ between very and less severe malaria. By multivariate analysis, only lower plasma albumin and higher sTREM-1 were associated with greater severity, with intermediate accuracies.

Conclusions: During imported malaria, the most useful biomarkers associated with severity seem to be plasma albumin and sTREM-1; and among parasite-related parameters, PfHRP2 was more strongly associated with severity than parasitemia was.