As the emerging Zika virus continues to rapidly spread in the Pacific, so do fears of the potential consequences, especially in light of strong links between the growing epidemic and a brain disorder in newborns. There’s no available treatment or vaccine, and given the length of time it takes to develop such interventions, it will be years before we see any on the market. But there could be a solution: genetically modified mosquitoes.
Zika virus is spread by the same mosquito as dengue and another disease called Chikungunya, a species called Aedes aegypti. Scientists in the U.K. have developed and are implementing an effective way to curb their populations, which involves genetic manipulation and controlled insect release programs.
Created by biotech firm Oxitec, the so-called “friendly Aedes aegypti,” or OX513A, contains a gene that causes offspring to die before reaching reproductive age. So when males are released into mosquito-riddled areas, they successfully compete with those in the wild for females, ultimately leading to a reduction in numbers, but not eradication, without the need for pesticides.
“When you take out this one mosquito – Aedes aegypti – you also take out all of the diseases it carries,” Oxitec communications manager Chris Creese told IFLScience. “That’s why this approach is so powerful. And it does not harm other species. So it is a win-win.”
Infographic demonstrating how Oxitec's mosquitoes are generated. Oxitec
Following extensive safety and performance evaluations, the mosquitoes have been trialed with success in a number of countries in Latin America and Asia. The results were so encouraging in Brazil that the project has now been expanded in the city of Piracicaba, where in just nine months mosquito larvae was reduced by 82 percent in the trial area, the CECAP/Eldorado district. Importantly, this had a demonstrable impact on disease rates.
“It is important to remember that in 2014/15 CECAP/Eldorado had 133 cases of dengue, the highest incidence in the city of Piracicaba,” Pedro Mello, Piracicaba’s secretary of health, points out. “In 2015/2016, after the beginning of the Friendly Aedes aegypti Project, we had only one case.”
Piracicaba’s program involved releases that offered coverage for 5,000 people, and it’s now been extended for another year. In addition, a letter of intent to expand coverage to up to 60,000 residents has also been signed, and plans are being put in place to build a new mosquito factory that could ultimately bump this number up to 300,000.
“The CECAP/Eldorado district had the highest incidence of dengue which is why it was the first target,” said Creese. “Now, following a reduction in mosquitoes and dengue cases, the continuation and expansion is to stave off dengue, as well as Chikungunya and now Zika virus to prevent an epidemic.”
While the CDC has issued travel guidance to curb Zika spread, and some countries have even gone so far as to recommend against women becoming pregnant due to an apparent spike in associated birth defects, Creese emphasizes that these are not long-term solutions. Hopefully, we will continue to see positive results from these modified mosquito programs, which will encourage other countries to get on board and begin to sustainably tackle these insect-borne diseases.