Despite being a preventable and curable disease, a child dies in Africa every minute from malaria, contributing to a worldwide death toll of a staggering half a million individuals. But scientists are on the case, working on new control measures, treatments that tackle resistant parasites and even vaccines. And we may have another invaluable addition to the anti-malaria arsenal on the horizon, as researchers have just developed a rapid diagnostic test that doesn’t require even a single drop of blood.
That is not to suggest that having to take blood is the main reason that existing malaria tests aren’t ideal for developing regions, where the majority of cases occur. But the blood samples need analyzing, which requires a trained technician, chemical reagents and lab equipment, such as microscopes. Furthermore, it can take around an hour for the diagnosis to be made through traditional microscopy techniques.
Some rapid fingerprick tests are already in existence that don’t require trained personnel, but a major drawback is that all are known to sometimes give false results. Additionally, they can be costly, have a limited shelf life and poor stability in heat, which isn’t ideal for tropical countries ravaged by the disease.
Impressively, the new device claims to overcome all of these problems, and it’s the first completely non-invasive test developed so far, which is amazing considering the organism that causes malaria, Plasmodium falciparum, is a blood-borne pathogen.
As described in Emerging Infectious Diseases, it works by using low-cost lasers to deliver harmless pulses of energy to blood vessels through the skin, which subsequently get absorbed by crystalline waste pigments produced when the malaria parasite digests blood, or more specifically hemoglobin. Upon absorption, heat is created in the local area that evaporates the liquid surrounding the nanocrystals, creating a tiny, transient bubble inside the parasite. When the bubbles collapse, or pop, they can be detected using an acoustic sensor that is integrated into the probe.
Amazingly, the device can detect infections in just 20 seconds, and it doesn’t require any reagents, which are estimated to cost around $100 million each year, New Scientist reports. It’s also battery powered and thus doesn’t need electricity, and tests don’t require trained personnel. Although each device is estimated to come with a $15,000 price tag, a single unit should be able to test 200,000 people, which works out at around 8 cents per test.
So far, the prototype has only been tested on six individuals, where it was able to successfully spot the one infected individual out of the group. The next phase of testing will involve field trials in Africa, which should hopefully reveal whether the device is able to detect infections in those with a low parasite load. The team also has some improvements to make – currently, darker skin tones with more melanin generate background readings that could be misconstrued as a positive result. But the researchers think that employing a different wavelength of light could alleviate this issue, which currently represents a major hurdle for its use in many countries.
1