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Zika virus

US scientists to trick mosquitoes with zika to breed themselves out of existence

PUBLISHED : Thursday, 20 July, 2017, 12:46am
UPDATED : Thursday, 20 July, 2017, 12:46am

This summer, a Silicon Valley tech company will have millions of machine-raised, bacteria-infected mosquitoes packed into windowless white vans, driven inland and released into the wild or, at least, the streets of Fresno, California.

And, yes, Fresno County officials are encouraging this.

It’s all part of the “Debug Fresno” project, which aims to cut down on the number of Aedes aegypti mosquitoes, an unwelcome invasive species that arrived in California’s Central Valley in 2013. In addition to being potential carriers of the Zika, dengue fever and chikungunya viruses, the Aedes aegypti also adapted rapidly to the area’s residential neighbourhoods, to the chagrin of residents and officials alike.

“It’s a terrible nuisance, a terrible biting nuisance. It’s changed the way people can enjoy their back yard and it’s a threat for disease transmission,” said Steve Mulligan, district manager for the region’s Consolidated Mosquito Abatement District. “So we’re looking for new ways to eliminate it.”

To do so, district officials have partnered with tech companies to use an approach that has gained traction in recent years. Inside a lab, millions of the mosquitoes will be infected with Wolbachia bacteria, which changes the reproductive ability of males. Afterward, only those male mosquitoes which don’t bite will be released to mate with unsuspecting female Aedes aegypti.

Even if the females lay eggs, those eggs will never hatch. Eventually, officials hope to reduce the population of Aedes aegypti, generation by generation, until they are eliminated from the area.

“It’s kind of contrary to what a person would think. ‘What, you’re doing what? You’re releasing mosquitoes to control mosquitoes?’ ” Mulligan said. “We are releasing male mosquitoes because male mosquitoes do not bite and cannot transmit disease.”

If all this sounds like the opening of a sci-fi movie, that’s because the endeavour represents a cross-section of the health-care and technology industries. The “Debug Fresno” project is a continuation of a similar strategy that started last summer, when county officials partnered with Kentucky-based MosquitoMate to release 40,000 Wolbachia-infected male mosquitoes each week in Fresno County.

Zika virus threat may be even more potent this year

This year’s mosquitoes are being bred and distributed by Verily, a subsidiary of Alphabet that was formerly known as Google Life Sciences. Verily officials estimate that this year, they will release 1 million mosquitoes per week in Fresno County, more than 25 times last summer’s numbers. That is possible because they’ve developed ways to breed and separate male and female mosquitoes on a larger scale.

“Automated sex-sorting is a key advancement for this research,” Verily spokeswoman Kathleen Parkes said in an email. “Traditionally, mosquito sex-sorting is a very labour-intensive process. Verily has developed a system that uses computer vision algorithms to identify the sex of the mosquitoes and only let the males through.”

Scientists have studied ways to use Wolbachia bacteria to control mosquito populations since the 1980s, but a number of successful field tests have shown its effectiveness in recent years. In 2011, Australian researchers released batches of Wolbachia-infected female mosquitoes around two neighbourhoods near Cairns, Queensland, and then monitored the mosquito populations there.

Hong Kong woman who travelled to South America becomes first imported Zika case of the year

Though there have been no local infections of Zika or dengue reported in California, Mulligan said they want to be prepared in case someone travels back from a country where they were infected. An Aedes aegypti mosquito could easily spread the virus from one person to another, as happened in Florida and parts of Texas last year, he said.

In a video produced to educate Fresno County residents about the project, Jodi Holeman, a director with the region’s mosquito abatement district, agreed.

“Even though they’re not actively and currently transmitting disease in California, it’s our job to try to stay ahead of these diseases,” she said.