An army of bacteria-infected mosquitoes will be deployed across two major cities in Colombia and Brazil in early 2017, in the latest attempt to fight Zika and other mosquito-borne diseases, the Australia-based Eliminate Dengue program announced Wednesday.
The U.S. and U.K. governments, along with NGOs like the Bill and Melinda Gates Foundation, contributed a total of $18 million to fund the first large-scale trial of the promising new mosquito-control tactic, which utilizes mosquitoes carrying Wolbachia bacteria to halt the spread of disease. Small-scale testing has indicated that the bacteria reduces the insect's ability to transmit viruses to people.
For the upcoming trials, the Wolbachia-infused mosquitoes will be released over Rio de Janeiro and Antioquia, Colombia, targeting about 2.5 million people in each city, according to Nature. The project will target the disease-spreading abilities of the aedes aegypti mosquito, which is responsible for most of the 390 million dengue fever infections annually. It's also a major carrier of Zika, Chikungunya, and yellow fever.
The large-scale Wolbachia offensive comes after more than a decade of research. The bacteria naturally occurs in several mosquito species, except for aedes aegypti. Through the Eliminate Dengue Program, researchers at Australia's Monash University developed methods for infecting the aedes with Wolbachia. The bacteria is transferred to the mosquitoes in a lab before the insects are let out into the world, with hopes they will reproduce with local populations and infect their offspring.
In the last five years, the method has been tested in several small-scale field trials in Australia, Indonesia, Vietnam, Brazil, and Colombia. For these trials, mosquitoes were released over smaller areas reaching only thousands of residents. Within weeks of their start date, trails in Australia, Indonesia, and Vietnam saw 90 percent of the mosquitoes carrying Wolbachia.
As the new trials get underway, the next step is to assess the impact the so-called "Wolbachia method" has on decreasing the transmission of dengue, Zika, and other diseases in large populations.
Earlier this year, the World Health Organization recommended large-scale deployments. The call came as the Zika virus continued its unprecedented spread through the Western Hemisphere. The outbreak grabbed headlines in 2015, when Brazil reported an uptick in debilitating birth defects like microcephaly, which has been linked to Zika.
"Using Wolbachia to reduce the transmission of mosquito-borne diseases has the potential to greatly reduce the global health burden and socioeconomic cost of Zika and other related infections," said Dr. Mike Turner, head of infection and immunobiology at the U.K.-based medical charity Wellcome Trust, which is also funding the upcoming trials.