Folded sheets of waxed paper could help bring fast, affordable, and reliable field tests for diseases such as malaria to remote parts of the developing world.
In a paper published in Proceedings of the National Academy of Sciences, researchers from universities in Scotland and China, working with the Ugandan Ministry of Health, describe how their folded paper, prepared with a printer and a hot plate, has helped detect malaria with 98 per cent sensitivity in infected participants from two primary schools in Uganda.
Malaria affects over 219 million people in 90 countries and in 2017 the disease killed 435,000 people. Arresting and reversing the spread of the disease requires diagnosis in people who are infected but who do not display any symptoms. This problem can only be addressed by widespread field tests but current assessments, , which rely on PCR (polymerase chain reaction), can only be carried out under lab conditions.
Led by researchers from Glasgow University, the team developed a new approach to diagnostics that uses paper to prepare patient samples for a different type of detection process known as LAMP (loop-mediated isothermal amplification), which is more portable and better-suited for field use.
The new platform is said to use a commercially-available printer to coat the paper in patterns made from water-resistant wax, which is then melted on a hotplate, bonding the wax to the paper.
A blood sample taken from a patient via fingerprick is placed on in a channel in the wax, then the paper is folded, directing the sample into a narrow channel and then three small chambers which the LAMP machine uses to test the samples’ DNA for evidence of Plasmodium falciparum, the mosquito-borne parasitic species which causes malaria. The test can be completed on-site in less than 50 minutes.
Lead author Prof Jonathan Cooper of Glasgow University’s School of Engineering said: “We tested our approach with volunteers from two primary schools in the Mayuge and Apac districts in Uganda. We took samples from 67 schoolchildren…and ran diagnostic tests in the field using optical microscopy techniques, the gold standard method in these low-resource settings, a commercial rapid diagnostic procedure known as a lateral flow test and our LAMP approach. We also carried out PCR back in Glasgow, on samples collected in the field.
“Our diagnostic approach correctly diagnosed malaria in 98 per cent of the infected samples we tested, markedly more sensitive than both the microscopy and lateral flow tests, which delivered 86 per cent and 83 per cent respectively.
“It’s a very encouraging result which suggests that our paper-based LAMP diagnostics could help deliver better, faster, more effective testing for malaria infections in areas which are currently underserved by available diagnostic techniques.”
The team’s paper, titled ‘Paper-based Microfluidics for Diagnosing Malaria in Low Resource Rural Environments’, is published in PNAS. The research was supported by funding from the UK Global Challenges Research Fund, the Scottish Funding Council, and the Engineering and Physical Sciences Research Council (EPSRC).