Winter is waning and Spring is approaching. That means that outdoor time in most places is switching back into mosquito season. If you’ve been in touch with world news recently, you’ve probably learned one more reason why that is kind of a bad thing – the mosquito-born Zika virus. But even as the first cases of Zika are identified in the United States, a high tech response is already in development to combat the spread.


In a laboratory in the Brazilian state of São Paulo, scientist from Oxitec, based in U.K., are breeding thousands upon thousands of male mosquitoes. This may sound like the opposite of what the world – and especially Brazil – needs right now, but these mosquitoes are the good guys. Or at least, that’s the idea.

All progeny of matings between RIDL males and wild females die. (Oxitec)

Due to DNA changes from being cooked up in the lab, these genetically modified insects can only survive for 4 days. They far outnumber the native, non-modified males in the neighborhoods where Oxitec is spreading them. So they mate with the native females at higher rates, beating out the native males. That’s when the more important change happens. The eggs that hatch from this breeding will never reach adulthood. Because of this, there are fewer and fewer mosquitoes to spread disease.

Of course, the disease they’ve been tracking in this case is not Zika – it’s Dengue fever, an illness which has affected over 1.5 million people in Brazil. The results in this fight against Dengue (the pilot program has caused cases in the local neighborhoods to plummet) will almost certainly apply to the Zika virus as well. That’s because it is spread by the same species of mosquito. That species thrives in warm- tropical or subtropical climates so there are so far no worries about running into them in colder climates.

Dengue Fever

Brazil actually beat this kind of mosquito, Aedes Aegypti, decades ago to combat yet another illness, yellow fever. This was achieved through comparatively low-tech methods of spraying insecticides and getting the population on board with eliminating standing water. Unfortunately, decades later the mosquito appeared again. Since it can lay eggs in as little as a bottle cap of water, the mosquito was able to spread quickly and easily.

Already noted, the idea is that these genetically modified mosquitoes will be the good guys in this latest fight. Some are concerned about the moral and ethical implications of tinkering with living creatures in this way. Other tinkering being used, or still investigated, is infecting laboratory grown mosquitoes with a certain bacteria to prevent them from spreading disease or alternating their DNA to just eliminate them altogether.

The general public is often afraid of the unforeseen effects of introducing GMOs (Genetically Modified Organisms) into the world. In the case of the “Friendly Aedesm,” the built-in four day lifespan may largely prevent these. Though that doesn’t prevent some conspiracy theories about the company and the project.

Oxitec staff shake genetically engineered mosquitoes from pots in the back of the vehicle (

Another possible concern is that all of this research is meant to lead up to commercial uses. The mosquitoes would be available for sale to treat areas at risk for Dengue, Zika, or a third infection called Chikunguya. Many people are more comfortable with the idea of genetic modification when it is for research or charitable purposes. The idea of doing it for profit, especially profit from people scares of a disease, is questionable. Brazil is not a country flush with cash and is the hot spot for these diseases.

Ultimately, it’s hard to know what will end the Zika and Dengue fever outbreaks in Brazil and beyond. Perhaps a vaccine will be developed or perhaps the DNA splicing of scientists will take care of things. Regardless, using normal precautions against mosquitoes, like long sleeves, repellent, and mosquito netting, will go a long way. An ounce of prevention may be worth a ton of genetically modified mosquitoes.

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