Scientists have developed a simple and affordable origami-style paper device that can accurately and quickly detect diseases such as malaria in the remote parts of the developing world.
A study, published in the journal Proceedings of the National Academy of Sciences, describes for the first time how folded wax 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 is one of the world's leading causes of illness and death, affecting more than 219 million people in 90 countries around the globe, and killing 435,000 people in 2017 alone, said researchers from the University of Glasgow in the UK and Shanghai Jiao Tong University in China.
A significant issue for arresting and reversing the spread of the disease is diagnosing it in people who are infected but who do not display any symptoms, a problem which can only be addressed by widespread field tests.
However, current tests, which rely on a process known as polymerase chain reaction (PCR), can only be carried out under laboratory conditions, making them unsuited for use in remote locations.
The team developed a new approach to diagnostics. It uses paper to prepare patient samples for a different type of detection process known as loop-mediated isothermal amplification, or LAMP, which is more portable and better-suited for use in the field.
The origami platform uses 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.
"We tested our approach with volunteers from two primary schools in the Mayuge and Apac districts in Uganda," said Professor Jonathan Cooper of the University of Glasgow.
"We took samples from 67 schoolchildren, under strict ethical approval, 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," he said.
The approach correctly diagnosed malaria in 98 per cent of the infected samples tested, markedly more sensitive than both the microscopy and lateral flow tests, which delivered 86 per cent and 83 per cent respectively, researchers said.
"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," they said.
"These are challenging environments for any test of this type, with no access to the kinds of refrigeration, special equipment and training that more traditional diagnostic procedures require, so it's very encouraging that the diagnostic techniques we have developed have proven to be so sensitive and reliable," said Julien Reboud of the University of Glasgow.
"With malaria infections on the increase in 13 affected countries according to a World Health Organisation report released last year, it's vital that new forms of diagnosis reach the people who need them, and we're committed to developing our approach to paper-based LAMP diagnostics further after this encouraging study," Reboud said.
