In a new study, University of Alberta Canada researchers said they have developed an affordable one-step test for dengue that requires just a small blood or plasma sample and a portable tester.
"You could take somebody's blood and run a single test to see what they have," said Ninad Mehta, lead author of the study. "You would know in about two hours what it is." Mehta conducted the study while working in the University of Alberta school of Public Health under Stephanie Yanow, who has spent years working on diagnostic tests for malaria, Medical Xpress reported.
Diagnosis is one of the biggest challenges in treating tropical fevers. Early dengue symptoms resemble malaria, chikungunya, Zika and other diseases. Rapid diagnostic tests can detect antigens or proteins, but they aren't always specific enough and can lead to false positives. More precise diagnosis requires expensive equipment, multiple steps and training. In remote areas where the disease is rampant, it's not always feasible.
Mehta's dengue test would combine the best of both worlds: a highly specific test that's affordable and portable.
It depends on a molecular technique called RT-PCR, which involves finding a stable sequence of viral RNA, translating it into DNA and multiplying the genetic material to the point where it can be detected. It piggybacks on the growing availability of Open PCR machines, a versatile DNA-detection technology that has become cheaper thanks to crowdfunding and open-source technology.
Because there are four distinct variants of the dengue virus, Mehta had to find specific genetic material common to all four but not found in viruses with similar symptoms. He focused on a 253-nucleotide sequence of RNA, which was tested on 126 archived samples from a dengue study in the Philippines. The results were compared with other types of testing.
The test held up well to existing kits, particularly in the first four days of symptoms when the presence of the virus is highest. At under $5 per test, Mehta believes this testing could help public health agencies get better bang for their buck.
"When you start treating one disease, another pops up," Mehta said. "It's a game about shifting resources whenever you can."Mehta hopes his work could help save lives, but he recognizes it still could be years away. Because the new dengue test requires cold chemicals, Yanow's lab is looking at using vacuum-drying to create a powder that could withstand the heat in tropical settings. More work will be needed for field trials.