Stopping Zika Virus at the Source: Mosquitoes

Genetically altered mosquitoes might help stop advance of Zika virus

When it comes to the Zika virus, fighting fire with fire is an old expression that may have a new meaning.

Like yellow fever and malaria, Zika is spread by infected mosquitoes. The virus doesn't hurt the insect, leaving it free to pass on Zika to anyone it bites. Many people who are infected have no or just minor symptoms. However, Zika may cause a birth defect called microcephaly which harms brain development in utero. There are also some indications it may cause Guillain Barre syndrome, which is similar to polio. At this time, neither a vaccine nor a specific medication can combat Zika. Strategies to prevent the spread of Zika basically boil down to two major options at this point:

  • Prevent the mosquito from biting with repellents, window screens, mosquito netting and clothing

  • Eliminate the mosquitoes

Dealing with Mosquitoes

The mosquito that spreads Zika virus is the Aedes mosquito, which is widespread in the Western Hemisphere. Unlike mosquitoes that prefer swamps or agricultural lands and come out at night to feed, Aedes mosquitoes prefer city life and feed during the day. Since they hunt during the day, mosquito netting -- which is used a to protect people at night in many tropical countries -- isn't effective. Aedes can breed in very tiny puddles or other stagnant water sources, which makes it difficult to spray insecticides. Many of the insecticides that would be most effective are also toxic to other insects and birds, and at least one – DDT -- is known to cause cancer. Although humans see them as annoying little pests, mosquitoes are a major food source for birds, bats, fish, frogs and other insects. Eliminating them entirely could have serious ecological consequences.

A Different Solution

A potential third option is to decrease mosquito numbers through preventing mosquitoes from becoming adults. Only adult females bite humans and other animals. Males and immature mosquitoes are no threat. Oxitec, a British company, developed a genetically engineered male mosquito that will breed normally. The young, however, die before they become mature. In one experiment in a Piracicaba, Brazil neighborhood, an article in the New York Times reports wild mosquito larva populations dropped by more than 80 percent. Oxitec was acquired by the American biotechnology firm Intrexon in 2015.

What You Can Do

For now, protection and prevention are the watchwords in dealing with Zika virus. Eliminate sources of standing water if possible. Make sure window screens are in good repair. Pregnant women should take extra precautions in areas where Zika has been found. Use EPA-registered repellents and wear long-sleeved shirts and pants when you go outside. The Centers for Disease Control and Prevention recommends that pregnant women not travel to areas where Zika is prevalent. If you feel ill, especially if you've traveled to South America recently, consult a physician.