While malaria has essentially disappeared in many countries, it still continues to ravage many parts of the world. The places where it survives tend to be poor and remote, and access to clinical laboratories with proper stains and microscopes sparse. Moreover, properly trained technicians that can analyze the slides can also be a rarity. Researchers from the Singapore-MIT Alliance for Research and Technology (SMART) have now developed a new malaria test that doesn’t require any staining and can be used by minimally trained personnel out in the field.
Unlike traditional malaria diagnostics that spot Plasmodium species via a microscope, the new test uses magnetic resonance relaxometry (MRR) powered by a .5 Tesla magnet to spot hemozoin crystallites, a metabolic byproduct of the parasite. Because the crystals affect the magnetic spin of hydrogen atoms, magnetic fields can be used to detect their presence by watching how hydrogen behaves. A primary magnetic field is used to align the atoms, while a second, weaker field is used to disturb this alignment. When some of the atoms are affected by the hemozoin crystals, the response to the changing secondary field is noticeable because the atoms don’t settle down together in synchrony. The prototype is currently the size of table-top laboratory equipment, but the team behind it plans on miniaturizing it into a handheld device.
Hemozoin crystals are produced in all four stages of malaria infection, including the earliest stages, and are generated by all known species of the Plasmodium parasite. Also, the amount of hemozoin can reveal how severe the infection is, or whether it is responding to treatment. “There are a lot of scenarios where you want to see the number, rather than a yes or no answer,” Han says.
In this paper, the researchers showed that they could detect Plasmodium falciparum, the most dangerous form of the parasite, in blood cells grown in the lab. They also detected the parasite in red blood cells from mice infected with Plasmodium berghei.
This new technique is “more sensitive, less error-prone, and requires less blood sample as compared to the standard blood-smear protocol,” says Donhee Ham, a professor of electrical engineering at Harvard University who was not part of the research team. “I think there is a strong potential here, and I look forward to its further development for reliable field deployment.”
Study in Nature Medicine: Micromagnetic resonance relaxometry for rapid label-free malaria diagnosis…
MIT News: A new way to diagnose malaria…