Over the past several decades, malaria diagnosis has changed very little. After taking a blood sample from a patient, a technician smears the blood across a glass slide, stains it with a special dye, and looks under a microscope for the Plasmodium parasite, which causes the disease.
This approach gives an accurate count of how many parasites are in the blood - an important measure of disease severity - but is not ideal because there is potential for human error.
A research team from the Singapore-MIT Alliance for Research and Technology (SMART) has now come up with a possible alternative.
The researchers have devised a way to use magnetic resonance relaxometry (MRR), a close cousin of magnetic resonance imaging (MRI), to detect a parasitic waste product in the blood of infected patients.
This technique could offer a more reliable way to detect malaria, said Jongyoon Han, a professor of electrical engineering and biological engineering at Massachusetts Institute of Technology (MIT).
"There is 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 bio-marker that does not require any biochemical processing of samples," said Han, one of the senior authors of the research.
The new system detects a parasitic waste product called hemozoin. When the parasites infect red blood cells, they feed on the nutrient-rich hemoglobin carried by the cells.
As hemoglobin breaks down, it releases iron, which can be toxic, so the parasite converts the iron into hemozoin - a weakly paramagnetic crystallite.
Those crystals interfere with the normal magnetic spins of hydrogen atoms. When exposed to a powerful magnetic field, hydrogen atoms align their spins in the same direction.
When a second, smaller field perturbs the atoms, they should all change their spins in synchrony - but if another magnetic particle, such as hemozoin, is present, this synchrony is disrupted through a process called relaxation.
The more magnetic particles are present, the more quickly the synchrony is disrupted.
Researchers used a 0.5-tesla magnet, much less expensive and powerful than the 2- or 3-tesla magnets typically required for MRI diagnostic imaging.
The current device prototype is small enough to sit on a table or lab bench, but the team is also working on a portable version that is about the size of a small electronic tablet.
After taking a blood sample and spinning it down to concentrate the red blood cells, the sample analysis takes less than a minute.
The research was published in the journal Nature Medicine.