Magneto-Optic Device Rapidly Detects Malaria

A device uses magneto-optic technology (MOT) to detect hemozoin, a waste product of the malarial parasite, in blood in less than a minute.

Hemozoin crystals are weakly magnetic and have a distinct rectangular form. They also exhibit optical dichroism, which means that they absorb light more strongly along their length than across their width. When aligned by a magnetic field they behave like a weak Polaroid sheet such as used in sunglasses.

Engineers from the Universities of Exeter (Devon, UK) and Coventry (Coventry, UK) created the new device, which could be as effective as the rapid diagnostic tests (RDTs) currently used in the field, but much cheaper and faster. The team is now working on a non-invasive version of the device, and with a team from the department of biomedical research, Royal Tropical Institute (KIT; Amsterdam, The Netherlands), is planning to trial in Kenya later in 2008.

RDTs use a chemical agent to detect antigens associated with the malarial parasite. One of the problems with RDTs is that they need to be kept within a given temperature range, which is difficult in hot climates. The disposable kits cost between US$1.50 and $4.50 each and take around 15 minutes to deliver a reading.

High-power microscopy is still the best method available for malaria diagnosis and has been used for more than a century. Unfortunately, it is time-consuming and requires expensive equipment and specialist medical skills, which are rarely available in villages in rural areas in malaria endemic countries. Over the last decade RDTs have been developed, which allow for faster diagnosis in the field, but these are too costly to be viable for developing countries.

In many communities where malaria is having a severe impact on health, there is no testing for malaria and young children who have a fever are given anti-malaria drugs as a matter of course. This has contributed to the malarial parasite becoming increasingly resistant to the common antimalaria drugs. Malaria is a disease for which there is still no vaccine.

Prof. Dave Newman of the University of Exeter's School of Engineering, Computing, and Mathematics, said, "There is an urgent need for a new diagnostic technique for malaria, particularly in the light of global warming, which threatens to spread the disease into new parts of the world, including southern Europe. The early results from our device are very promising and hugely exciting. We expect to ultimately produce a sensitive, noninvasive device that will be cost effective and easy to use, making it suitable for developing countries, where the need is greatest.”

The preliminary results appeared online in the Biophysical Journal in April 2008.


Related Links:
University of Exeter
University of Coventry
Royal Tropical Institute