The battle against the Zika virus, which can cause birth defects and paralysis, has been taken to the source.

The deadliest creatures on Earth — mosquitoes — kill 725,000 people every year by passing on malaria, dengue fever, yellow fever and other diseases. Now the insects are blamed for spreading Zika, infecting 3 million to 4 million people across Latin America in the last year.

Conventional mosquito control efforts involve spraying pesticides where the insects breed. But mosquitoes have developed resistance to many pesticides, and the spray means other helpful bugs die. The World Health Organization says that traditional pesticides have had no significant impact on slowing other mosquito-borne diseases.

A St. Louis startup biotech company says it has another solution. Forrest Innovations of Creve Coeur plans to breed and release sterile mosquitoes to prevent reproduction and eventually reduce their population. Their first target: Rio de Janeiro, Brazil, which has seen the world’s largest Zika outbreaks and will host the upcoming Summer Olympics.

“If we stop the mosquito, we can stop Zika, West Nile or any other viruses we might see in the next five years,” said Nitzan Paldi, Forrest’s CEO. Israel-based Forrest Innovations moved its American headquarters to the Bio Research and Development Growth Park at the Danforth Plant Science Center last year.

The concept is not new. Agriculture scientists have long used radiation to sterilize fruit flies, which are then released to kill off the crop-destroying pest. But fruit flies are much sturdier than mosquitoes, and radiation tends to kill the mosquito.

Forrest’s mosquito control program, called NoMoreMos, involves a different technique to sterilize male mosquitoes at a larval stage. After the males are sorted by machine (females weigh slightly more than males), the larvae receive a topical application of a solution that renders them sterile but does not modify their genetic code.

It is more efficient to sterilize males and prevent them from fertilizing females’ eggs. And male mosquitoes don’t bite, since only females need blood meals for egg development. The idea is to outnumber the wild male mosquito population with the sterile males, who will win the competition for females’ attention.

“If you release 10 sterile males for every male that is living in the environment, you are reducing the population by 90 percent every generation,” Paldi said.

How to distribute sterile mosquitoes over vast areas of rain forests or other areas plagued by mosquito-borne diseases is a challenge. While fruit flies can be successfully dropped from planes, mosquitoes disintegrate in the process.

Forrest Innovations teamed up with another company that created a mechanism for mosquitoes to survive air drops. While executives were hesitant to release many details, they say the plan has worked in trial runs.

They face competition from the British biotech firm Oxitec, which has genetically modified the Aedes mosquito so the males produce offspring that can’t reproduce.

The U.S. Food and Drug Administration has granted preliminary approval for Oxitec’s plan to release the insects in Florida after determining there would be no significant impact to human, animal or plant life from the experiment.

But Oxitec’s plan has been met with some public opposition to genetically modified organisms, or GMOs.

Aside from not genetically modifying their mosquitoes, Forrest has another advantage with its existing labs and employees in Brazil. The company chose to work in the country before the Zika outbreak mainly because of the threat of dengue fever, a deadly mosquito-borne virus endemic to tropical areas. Zika has shifted the company’s focus to the more immediate concern of preventing transmission among visitors and athletes during the Olympics.

“We have an audacious plan to be ready for the Olympics, to try to expedite everything and achieve in a number of months what we were planning to do in two to three years,” Paldi said.

The World Health Organization declared last month that the explosive spread of Zika across Latin America is a global emergency due to its link to the spike in the number of babies born with microcephaly, or abnormally small heads, and an increase in the rare Guillain-Barre syndrome that can cause paralysis and death.

So far, Zika has triggered outbreaks in 41 countries. There have been 193 cases of Zika reported in Americans who have traveled to the countries, including one from Missouri and seven from Illinois.

Forrest executives are coordinating with the Brazilian government on their plan to release up to 25 million sterile mosquitoes each week starting in June and through the Olympics in August. After the Olympics, company leaders said they can see applications for their technology in other countries including the U.S. The Zika virus is now circulating in Puerto Rico and several Caribbean countries, and scientists believe its move into the southern U.S. is inevitable.

A concern for any plan to eliminate or greatly reduce the mosquito population is the potential effect on the ecosystem. Paldi said the Aedes mosquito, which carries dengue and Zika, is not native to Brazil or the U.S. and would likely have little effect on bats and birds that feed on it if it disappeared.

“Brazil survived nicely before it arrived,” Paldi said. “I’m much more concerned about the impact of humans on the experience of other species.”

Source: St. Louis Dispatch by Blythe Bernhard