US team develops device to detect Zika, dengue viruses in 30 minutes

A team of researchers that includes one of Indian origin, working at the Sandia National Labs, a part of the US Department of Energy, has developed a smartphone-controlled, battery-operated diagnostic device that can detect  mosquito-borne diseases like Zika, dengue and chikungunya within 30 minutes.

The device costs as low as $100, and works on the loop-mediated isothermal amplification (LAMP) diagnostic method, eliminating the need to process a biological sample such as blood or urine, before testing.

"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, chemical engineer and lead author of the paper.

LAMP also eliminates the need for extra sample preparation before testing.

"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.

Meagher and his team developed a technique known as quenching of unincorporated amplification signal reporters (QUASR), that involves tagging fragments of synthesised viral DNA called primers with fluorophores -- molecules that emit bright light signals.

QUASR then causes samples containing viral DNA / RNA to appear bright, while negative reactions remain dark.

For the Zika project, Meagher's team developed a novel algorithm that allows a smartphone sensor to act as a fluorimeter, detecting QUASR LAMP light signals if they appear.

To detect the virus with smartphone LAMP app 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.

This smartphone-based image analysis offers much greater detection certainty than the lab technician's naked eye, the authors said.

By enabling diagnosis in 30 minutes, 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.

Furthermore, Zika, dengue and chikungunya are spread by the same mosquito type and have similar early symptoms.

Sandia's prototype diagnostic tool could enable healthcare providers to test quickly for all three at the same time, preventing misdiagnoses.