Researchers including one of Indian origin have developed a new smartphone-controlled, battery-operated diagnostic device that costs just USD 100 and can detect Zika, dengue and chikungunya within 30 minutes. Testing for these mosquito-borne viruses currently requires a laboratory and patients have to wait days for results. The tests require instruments that are roughly the size of a microwave oven and can cost up to USD 20,000. This makes rapid testing unrealistic for limited-resource clinics in developing countries where the viruses are prevalent. "In addition to creating an app that serves as a simple interface to operate the device, we were able to adapt smartphone camera sensors to replace traditional laboratory sample analysis tools, allowing for unprecedented mobility," said Aashish Priye from Sandia National Laboratories in the US. The device is based on the loop-mediated isothermal amplification (LAMP) diagnostic method, which eliminates the need to process a biological sample, such as blood or urine, before testing. Conventional viral testing involves transporting a sample to a laboratory, extracting DNA or RNA from it and then multiplying the genetic materials through a process called polymerase chain reaction (PCR). Like PCR, LAMP copies viral DNA/RNA, but without the heating and cooling cycle, a heavy-duty power source is not needed. The addition of a few carefully designed biochemical agents allows a LAMP box to test a sample that is heated only once to 65 degrees Celsius for half an hour. "We've demonstrated that the chemistry we're using can amplify viral RNA directly from raw, unprocessed samples," said Sandia chemical engineer and project lead Robert Meagher. LAMP works so simply that the user need only place the smartphone on top of the LAMP box and open an app.
The app turns on the heater to initiate the LAMP reaction. Once the 30-minute testing period is up, the smartphone photographs the sample. The app then employs a novel image analysis algorithm to accurately determine the color and brightness of the glow emitted from the LAMP reaction. This smartphone-based image analysis offers much greater detection certainty than the lab technician's naked eye. Zika virus has been linked to severe fetal abnormalities, including microcephaly and congenital blindness, as well as neurological disorders that can strike people at any age. By enabling diagnosis in half an hour, the device could help clinicians make faster decisions about patient care and isolation, and rapidly alert public health authorities so they can take measures to prevent spread of the virus. Zika, dengue and chikungunya are spread by the same mosquito type and have similar early symptoms. Sandia's prototype diagnostic tool could enable care providers to test quickly for all three at the same time, preventing misdiagnoses. The same tool can also be adapted to detect other human or animal pathogens, researchers said. The research was published in the journal Scientific Reports.