Simultaneous identification of the four human Plasmodium species and quantification of Plasmodium DNA load in human blood by real-time polymerase chain reaction.

The incidence of imported malaria cases in travellers returning from endemic areas has considerably increased over the last few years. The microscopical examination of stained blood films is the gold standard method to confirm clinical suspicion of malaria but diagnosis is difficult in the case of mixed infections, low-grade parasitaemia, or forms altered by uncompleted treatment. We have developed a real-time polymerase chain reaction (PCR) for the simultaneous identification of the 4 human Plasmodium spp. and quantification of Plasmodium DNA in human blood. The rapid turnaround and reduction in the risk of PCR product carryover are major advantages compared with conventional PCR. In combination with conventional tests, this method could be a powerful tool for the diagnosis of malaria infections among travellers from endemic areas and during the follow-up of patients in reference centres involved in travel and tropical medicine. Quantitative real-time PCR could also be used for the follow-up of patients during drug resistance studies managed by national malaria programmes, the testing of new drugs, and vaccine trials.