A Fast, Cheap, and Reliable Test for Mosquito-Borne Diseases May Be on the Way
Zika, dengue, and chikungunya cases around the world are on the rise and current methods for diagnosing infection require time-consuming and expensive laboratory tests.
Researchers at Livermore, California's Sandia National Laboratories have created a process that could allow health workers to quickly diagnose the mosquito-borne viruses Zika, dengue, and chikungunya - with a smartphone.
The team created what it calls the LAMP box, which combines new biochemical agents for processing samples taken in the field, a 3D-printed sample holder, smartphone-compatible light filters, and an app that controls the phone's camera and reads the sample. The system, which costs around $100, can detect RNA from the three viruses in body fluids, like blood or urine, in about half an hour and for less than $20 per test.
Sandia says its technology is radically quicker, cheaper, and easier than the current standard for genetic testing, a system called polymerase chain reaction, which requires equipment costing up to $20,000, a steady supply of plug-in electricity, and a lengthy period of time to process biological samples in a laboratory.
Robert Meagher, a chemical engineer at Sandia, said the LAMP box prototype must undergo several years of clinical trials before being sold on the market.
"The components inside are all commercial off-the-shelf, and I can imagine putting together a kit with all the components, or selling it fully assembled," he said.
3D-printed box and smartphone app aside, at its core, the Sandia technology is a refined version of loop-mediated isothermal amplification - the LAMP in LAMP box. The process mixes synthesized viral DNA primed with fluorescent compounds and biological samples, which are allowed to incubate in the LAMP box. That DNA finds and attaches itself to any viral RNA in the sample and replicates. The sample is then exposed to fluorescent light and viewed through the smartphone-compatible filter. If any virus is present in the sample, the fluorescent DNA lights up.
Sandia's process can identify two or more virus types and greatly increases the luminescence of a positive sample, reducing false-positive results and making the sample clear enough to register on a smartphone camera.
Meagher said the innovation emerged from previous work monitoring viruses like West Nile in the field and developing a smartphone-compatible detection system for febrile illness.
Dr. Bill B. Messer of Oregon Health Sciences University said the technology fills a niche for virus detection technology that health care providers can use in low-resource environments.
"Point-of-care diagnostics has sort of been this promise out there ever since I began in dengue, which is now 17 years ago," he said. "This is the first thing that I have seen in quite a while that has made me say: 'Oh, wow, that's kind of a cool innovation that actually could be a real advance in point-of-care diagnostics.' And we can do it with devices that people already own, which is clever."
The developing world has been hit hard by mosquito-borne diseases like Zika, dengue, and chikungunya. Nearly 2 million people have been infected with chikungunya since 2013 and as many as 400 million people a year contract dengue, according to the US Centers for Disease Control and Prevention (CDC). Zika numbers worldwide are more difficult to pin down, although over 5,000 cases in the United States and another 38,000 in US territories have been reported, according to the CDC.
All three viruses have similar initial symptoms and are transmitted by the same Aedes aegypti mosquito, though Zika can be transmitted through body fluids as well. Vaccine trials for Zika and chikungunya are underway, and there is a partially effective vaccine for dengue, available in a few countries. But there are no cures for any of them.
Early detection is important, Meagher said, because it can provide public health authorities with opportunities to contain infections before they become full blown outbreaks. He noted that early detection of Zika, which can be spread through sexual contact, can help infected individuals protect their partners.
Sandia Labs isn't the only group working on virus detection technologies that might be used in the field. A multi-institutional group with collaborators from MIT, Harvard, University of Toronto, Boston University, Arizona State University, Cornell, and the University of Wisconsin created a paper-based Zika screening system last year.