You may have heard about the Zika virus in the news. It's the latest in a long line of mosquito-born illnesses that seems to be spreading in epidemic proportions across many countries in the Americas. While there are few immediate complications, health experts believe that Zika is responsible for microcephaly in babies of infected mothers. Microcephaly (abnormal smallness of the head) is a serious birth defect, and pregnant women are being urged not to travel to countries with known outbreaks.
The culprit is the Aedes aegypti mosquito, which has made its home in parts of Africa, Asia, the South Pacific, Australia, and the Americas. This mosquito has been responsible for the spread of yellow fever, dengue fever, and other dangerous viruses that have infected and killed thousands of people. And while efforts to reduce mosquito populations have been ongoing for many years, the emergence of the Zika virus has brought a renewed urgency to the fight.
Perhaps the most promising weapon against mosquitoes is the recent development of "gene drive" technology. A gene drive differs from an ordinary gene in an organism's DNA because its trait is passed to all of its offspring (rather than just 50%). A gene drive could thus be used to pass destructive genes to the Aedes aegypti mosquito, such as those that destroy female mosquito chromosomes, prevent female mosquitoes from flying, or cause a mosquito to be born male. By releasing genetically altered mosquitoes into the wild, female populations of the target species would be reduced with each generation, until the population is eradicated. Gene technology has already been used to help control the spread of malaria, however the approach is complicated by the fact that there are a number of diverse species that carry this disease. With dengue and Zika, the Aedes aegypti species is primary carrier.
One of the biggest advantages of the gene-drive-based approach is that it is species-specific. Traditional methods of control (insecticides and removing breeding sites) attack all mosquitoes, meaning the entire ecosystem is effected. Gene-drive technology would attack the Aedes aegypti while not affecting other (less harmful) mosquito species, potentially causing less damage to the environment and the surrounding ecosystem.
There are still concerns to this new approach, however. Most notably is whether the eradication of the Aedes aegypti could have any unintended consequences, like for example leaving room for some new or potentially more harmful species to emerge. And there have been looming fears about the broader impact of gene-editing technology and the possibility of its accidental or intentional misuse. But whether these fears will delay or prevent its use against the Zike mosquito remains to be seen.
Meanwhile, we will likely continue to see the spread and impact of Zika, and a vaccine against the virus looks to be at least a year away.
Source: MIT Technology Review
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