New tool identifies mosquito species in battle against Zika virus

A new diagnostic tool has been developed to quickly and cheaply identify a specific species of mosquito that carries diseases including the Zika virus.

Test determines whether a dead mosquito belongs to the Aedes aegypti species (Vivian Abagiu/University of Texas at Austin)

The new tool from The University of Texas at Austin can also determine whether the insect has come into contact with Wolbachia, a type of bacteria that keeps mosquitoes from spreading diseases.

The tool uses a smartphone camera, a small 3D-printed box and a simple chemical test to show whether a dead mosquito belongs to the Aedes aegypti species, which also carry dengue, chikungunya or yellow fever. As well as afflicting around 100 million people worldwide each year, the species also is closely linked to the tripling of cases of mosquito-borne diseases in the United States since 2004.

“Many of these diseases are spreading in areas where they weren’t common before,” said Sanchita Bhadra, a research associate in the Department of Molecular Biosciences and first author on the paper. “Having surveillance is important in conjunction with any kind of outbreak, and this method allows a rapid test in the field.”

The research appears in the journal PLOS Neglected Tropical Diseases.

The tool also detects the presence of a biopesticide called Wolbachia. In countries around the world and in 20 US states where the Aedes aegypti mosquito is present, scientists working in public health agencies have started to infect mosquitoes with Wolbachia by introducing the bacteria into a local mosquito population to help curb transmission of viruses.

According to the university, mosquitoes show no outward signs of having the bacteria and current diagnostic tests are hard to read, expensive and logistically cumbersome. Consequently, the new tool has the potential to provide a significant step forward for those hoping to monitor the effectiveness of Wolbachia.

“This test can happen without involving a lot of staff and equipment to make sure Wolbachia is effective and spreading as anticipated,” Bhadra said.

Public health groups trap and kill mosquitoes routinely in conjunction with monitoring efforts, but existing technology requires a complex process to extract nucleic acid from inside mosquitoes, often after they have been dead for days and have started to decay, leading to greater expense and the possibility of more errors in lab tests than the new technology.

The new diagnostic tool uses a smartphone’s camera and a simple test that can be done anywhere. It tests mosquitoes’ nucleic acid without requiring a complicated process to remove it. Dubbed loop-mediated isothermal amplification and oligonucleotide strand displacement (LAMP OSD), the probe delivers an unequivocal yes-or-no readout on a cell phone, with accuracy of greater than 97 per cent.

In addition to the tests to detect mosquito species and Wolbachia, the team also is exploring use of the technology to easily identify whether trapped mosquitoes are carrying Zika, dengue and other pathogens.