HEMOZION : New way to diagnose malaria

Red blood cells from a patient infected with Plasmodium falciparum.

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 

The new SMART 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.

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.

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.

The researchers are launching a company to make this technology available at an affordable price. The team is also running field tests in Southeast Asia and is exploring powering the device on solar energy, an important consideration for poor rural areas.

Journal Reference:

1. Weng Kung Peng, Tian Fook Kong, Chee Sheng Ng, Lan Chen, Yongxue Huang, Ali Asgar S Bhagat, Nam-Trung Nguyen, Peter Rainer Preiser, Jongyoon Han. Micromagnetic resonance relaxometry for rapid label-free malaria diagnosis. Nature Medicine, 2014; DOI: 10.1038/nm.3622