Washington: Scientists have developed a fast, reliable and inexpensive method to diagnose malaria that uses magnetic fields to detect the parasite's waste products in the blood of infected patients.
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.