Scientists have developed a novel way to diagnose malaria using magnetic fields. The affordable and quick technique can detect parasitic waste products in the blood of infected patients.
A research team from the Singapore-MIT Alliance for Research and Technology came up with the new test for the disease, caused by a mosquito-borne parasite, which killed an estimated 600,000 people in 2012.
The process of diagnosing malaria has remained the same for decades: a dyed blood smear is examined under a microscope for the Plasmodium parasite. According to the researchers, the method leaves potential for human error.
The new method uses magnetic resonance relaxometry, a close cousin of magnetic resonance imaging, to detect the parasite's waste products in the patient's blood.
The technology and expertise needed to identify the malaria parasite are not always available in the regions most affected by malaria, and technicians can interpret smears differently.
Jongyoon Han, a professor of electrical and biological engineering at MIT, said: "There is a real potential to make this into a field-deployable system, especially since you don't need any kind of labels or dye. It's based on a naturally occurring biomarker that does not require any biochemical processing of samples."
Finding malaria with magnets
Han's new system detects a waste product of the malaria parasite called hemozoin.
Plasmodium feeds on the nutrient-rich hemoglobin carried by the red blood cells it infects. As hemoglobin breaks down, it releases iron. As this can be toxic, the parasite converts the iron into hemozoin — a microscopic crystal that is attracted to, and can generate, weak magnetic fields.
When a blood sample is exposed to a powerful magnetic field, hydrogen atoms in it begin to spin in the same direction. When a second, smaller, field is introduced, their spin change in sync with each other. But if magnetic particles – such as hemozoin – are present, this synchronised behaviour is disrupted: a process called "relaxation".
For this study, the researchers used a 0.5 Tesla magnet. At about 100 times as strong as a fridge door magnet, this magnet was much less powerful, and cheaper, than the 9.4 Tesla magnets used in MRI machines, which can cost $2m (€1.5m, $1.2m).
This analysis takes less than a minute, and only about 10 microliters of blood is required, which can be obtained with a finger prick.
"This system can be built at a very low cost, relative to the million-dollar MRI machines used in a hospital," said the study's author Weng Kung Peng. "Furthermore, since this technique does not rely on expensive labeling with chemical reagents, we are able to get each diagnostic test done at a cost of less than 10 cents."
"The performance of the technique appears to be comparable, if not superior, to routine microscopy," Richard Maude, an epidemiologist from the University of Oxford who was not involved in the study, told told Scientific American.
The amount of hemozoin can reveal how severe the malaria infection is, or whether it is responding to treatment. Researchers are exploring powering the device on solar energy for poor rural areas.
The research was published in Nature Medicine.