Exciting malaria prototype can test people just by shining light through skin

Australian researchers have investigated whether a chemical-free, needle-free device can detect if someone has malaria.

The technology is still in its early stages, but if the research – published in PNAS Nexus – can be made to work, it would be a helpful tool fighting a disease that infects 247 million people a year.

“Currently it’s incredibly challenging to test large groups of people, such as the population of a village or town – you have to take blood from everyone and mix it with a reagent to get a result,” said Dr Maggy Lord, a medical entomologist at the University of Queensland.

“But with this tool we can find out very quickly whether a whole village or town is suffering from, or carrying, malaria.”

Malaria is a disease caused by several types of Plasmodium parasites. The two most common are Plasmodium falciparum and Plasmodium vivax. These can infect humans through the bite of certain mosquito species, which the parasites use as a host.

Malaria affects many of Australia’s nearby neighbours, including Papua New Guinea, Timor Leste and Indonesia. However, 95% of the world’s malaria cases — and 96% of the deaths — are in Africa.

“The biggest challenge in eliminating the disease is the presence of asymptomatic people in a population who act as a reservoir for transmission by mosquitos,” said Lord.

“The World Health Organisation has proposed large-scale surveillance in endemic areas and this non-invasive, affordable and rapid tool offers a way to achieve that.”

The device from the new study is a miniaturised, hand-held, near-infrared spectrometer. The machine shines a beam of light through the skin for around five seconds, creating a ‘spectral signature’ of the blood.

Malaria parasites infect the blood, sometimes with more than 100,000 parasites per microlitre, which the researchers suggest would change the spectral signature.

The team looked at 60 patients from a region in Northern Brazil, and those who had malaria symptoms were tested using the new device and the traditional, but highly sensitive, a PCR test. The researchers tested the device on the left and right arms, ears, and fingers.

The ear was the best place to gather data, with researchers finding that it was 92% accurate. It also produced no false negatives and only a few false positives.

“The spectral signatures collected from 27 malaria positive individuals, regardless of 1) their parasitaemia level and 2) whether they were positive with P. falciparum or P. vivax, were seen to be different from signatures of the 33 malaria negative individuals,” the team wrote in their new paper.

“We hypothesised that the invasion of Plasmodium parasites into the human host’s red blood cells results in significant structural, biochemical, and functional changes which generate unique infrared absorption peaks for malaria positive and negative individuals.”