An easy and quick technique for malaria diagnosis, based on detecting a by-product of malarial metabolism in infected red blood cells, is reported in Nature Medicine this week. The technique is more sensitive than previous techniques, and can be carried out by a portable detector in the field, providing diagnosis in a few minutes.

The ability to diagnose malaria infection early on in its progression is crucial to global efforts to eliminate the parasite that spreads the disease. The current gold standard technology for diagnosis is microscopic examination of blood samples for the parasite; this method is prone to human error and has reduced sensitivity at low parasitic loads. Other available detection techniques are not quantitative, are expensive and are impractical in the field.

To detect the presence of the malarial parasite Jongyoon Han and colleagues measured the increase of a metabolite called hemozoin in infected red blood cells. Hemozoin is formed when malarial parasites metabolize the iron-containing protein, haemoglobin, in red blood cells. The authors show that hemozoin has a magnetic signal that is detectable by a bench-top machine. Using this device, they show highly sensitive detection of the malarial parasite Plasmodium falciparum in human blood in minutes without any additional steps. They also show that they are able to detect the early stages of infection by the malarial parasite Plasmodium berghei in mice.