Biosensor Promises Early Malaria Diagnosis

By Rodrigo de Oliveira Andrade [SÃO PAULO] A strip of chromatography paper similar to that...

By Rodrigo de Oliveira Andrade

[SÃO PAULO] A strip of chromatography paper similar to that used in rapid pregnancy tests is the basis of a bio-sensor for detecting malaria that has been developed by Brazilian researchers.

The strip, designed for early diagnosis of infection caused by the Plasmodium falciparum parasites responsible for the most aggressive and lethal form of the disease, gives a result within 30 minutes of being immersed in a solution with samples of blood, serum or saliva of an infected person. Current tests take between two to ten days to give a result.

If the paper strip changes its colour, it means that histidinerich protein 2 (HRP2) — a protein excreted only by P. falciparum in the first days after the infection — is present into the bloodstream.

During lab tests, the device was able to detect the presence of the HRP2 even when the parasite had produced it in low quantities.

Early diagnosis of malaria is vital [in order] to increase the chances of treating infected people.

Osvaldo Novais de Oliveira

The bio-sensor has been tested with blood samples of both healthy people and people infected by the parasite. The samples were provided by the Parasitological and Entomology Laboratory of the Hospital das Clinicas at the University of Campinas (Unicamp) in Brazil.

The current cost of production for the test is estimated at US$0.50, according to Lauro Tatsuo Kubota, from the Chemical Institute of Unicamp and lead author of the study that describes the technology, published in the journal Sensors and Actuators B: Chemical.

“If production increases, its cost could be lowered,” Tatsuo tells SciDev.Net.

Malaria is transmitted by mosquitoes of the Anopheles genus that draw blood contaminated with Plasmodium parasites. The initial symptoms of the disease are similar across all malaria types (fever, chilling, headache and body aches) but the disease may become more severe depending on the causative agent.

Although the P. falciparum parasite is prevalent in Africa, it is also present in 20 Latin American countries, mainly Brazil, and is estimated to cause six deaths per 100.000 people every year across the region.

Osvaldo Novais de Oliveira, from the São Carlos Institute of Physics at the University of São Paulo, says the bio-sensor could have a high social impact by improving diagnosis, especially in areas far from urban centres.

“Early diagnosis of malaria is vital [in order] to increase the chances of treating infected people,” de Oliveira tells SciDev.Net. “But for this, [it] is indispensable to have a low-cost technology that can be broadly used, mainly by the most vulnerable populations.

According to Kubota, the bio-sensor needs to be tested with a larger number of samples in order to validate its results, and to verify how many samples the test can evaluate before losing its capacity to detect the HRP2 proteins.

When these tests conclude, the team behind the test will begin to negotiate with companies interested in producing and marketing the bio-sensor, a process that they say should not take longer than two years.

The study published in Sensors and Actuators B: Chemical is a result of projects funded by FAPESP, a SciDev.Net donor.

This article was produced by SciDev.Net’s Latin American & Caribbean desk.

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