Researchers have devised a new way of counting malaria parasites 'hiding' in human blood cells, which they say could lead to better diagnosis of the disease.
The research, led by Nick White at Thailand's Mahidol University, was published today (23 August) in PLoS Medicine.
Scientists usually judge the severity of a malaria case by looking at a patient's blood under a microscope and counting the number of parasites they see.
But this method counts only parasites circulating in the blood, and not those that have already entered blood cells to multiply. Infected cells tend to get trapped in the smallest blood vessels, restricting the blood flow, with serious consequences.
The multiplying parasites eventually make the blood cells burst, releasing a protein called pfhrp2.
White's team measured the amount of this protein in the blood of more than 300 people with malaria in Thailand.
They found that the higher the level of the protein, the worse the case of malaria.
This finding fits with the theory that the most harmful form of the parasite is the one that infects red blood cells.
The scientists say that this method could be used to gauge how severe a case of malaria is.
But they add that the method might need fine-tuning to apply it to other parts of the world.
In Africa, for instance, malaria affects people whose constant exposure to the parasite allows them to develop partial immunity to it. White's team suggests that proteins made by people's immune systems to fight infection might also reduce the amount of pfhrp2 in their blood.
This could lead health workers to underestimate the severity of malaria cases.
Nick White is on the advisory panel for SciDev.Net's forthcoming malaria dossier