As mosquito-borne viruses like Zika, Dengue, and Chikungunya continue to spread across the globe, rapid diagnosis and treatment are more important than ever. In a recent paper published in the journal PLOS Neglected Tropical Diseases, German researchers describe an inexpensive, portable test that could help speed up Chikungunya diagnosis in remote areas.
The word “chikungunya” means “to become contorted” in the Kimakonde language of southeastern Africa, and refers to the curled-up posture of people in pain. The symptoms of Chikungunya virus (CHIKV)—joint pain, muscle pain, and fatigue—are similar to those of a bad flu and will generally resolve on their own after a few days or weeks. But they also look a lot like the initial symptoms of Dengue fever, which can be fatal unless it’s treated quickly. The two illnesses are carried by the same mosquito species, Aedes aegypti and Aedes albopictus, and are found in the same parts of the world. Identifying which of these viruses a patient has can be a matter of life and death.
Current CHIKV tests rely on polymerase chain reaction, or PCR, which chemically amplifies any traces of RNA or DNA in a sample to make them easier to identify. But PCR is time- and cost-intensive and requires refrigeration, which makes it an impractical choice in remote areas. An international team of researchers decided to see if they could do better.
They set PCR aside in favor of a technique called reverse transcriptase recombinase polymerase amplification (RT-RPA), which they hoped would also amplify the RNA of the Chikungunya virus (CHIKV). To test their assay, the team ran samples from 58 patients with suspected CHIKV infection and another 20 whose infection had been confirmed through both a PCR scan and their new RT-RPA.
The results were promising indeed. The patients’ samples had included 18 different CHIKV strains, and the RT-RPA spotted them all. The new test correctly diagnosed 36 patients, and didn’t return a single false positive. The RT-RPA was slightly less sensitive than the PCR, but it was also faster and more shelf-stable.
“The CHIKV RPA assay presented here is a promising tool for CHIKV diagnostics at the point of need,” the authors write in their paper.
Still, the test isn’t ready for primetime just yet. In its present incarnation, the assay requires a lot of steps and pipetting, and costs around $5. Ideally, the researchers say, the process would be even simpler and max out at $1. They’re continuing to refine their product, and recommend combining it with Dengue and Zika tests, which “…would improve outbreak investigations, since the three viruses induce the same clinical picture upon infection and increasingly co-circulate in many parts of the world.”
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