The World Health Organization this month declared the Zika virus a global health emergency. Can anything be done to stop it?
Zika is spread by Aedes mosquitoes, which are also responsible for the spread of dengue fever, and thus far efforts to minimize their contact with human beings has been quite difficult. This has forced public health officials to take an innovative approach to the problem.
One proposed solution is to introduce genetically-modified mosquitoes (transgenic mosquitoes) into the wild population, an approach that’s been used in the past to control the spread of dengue fever. Genetic modification can attack the problem in many different ways. It can minimize the mosquitoes’ ability to transmit the virus. It can increase the insect’s resistance to the virus. Or, it can reduce a mosquitoes’ interest in biting humans.
Unfortunately, merely introducing a modified gene into a wild population is not enough. In order to become sufficiently widespread, the modified gene must spread through the population rapidly and remain active. Given these difficulties, it took years to develop large-scale transgenic mosquito tests. Thus far they seem promising: a recent test on dengue fever in Brazil seems to have been a big success. So there’s hope that this might work on the Zika virus as well. However, some scientists and anti-GMO activists caution that without careful management, transgenic mosquitoes might increase the virulence of pathogens like dengue and Zika.
Of course, introducing transgenic mosquitoes is just one way of tackling mosquito-born illness. Another involves controlling the mosquito population at the source. For instance, a research team in Iquitos, Peru, dusted attractive resting spots for adult female Aedes mosquitos with a toxic Juvenile Hormone Analog (JHA). Whenever the females lay eggs, the hormone guarantees that none of the hatchlings survive, thereby curtailing the growth of the mosquito population. Mosquito control is not a cure-all, but with luck, exploring cutting edge approaches like this and genetic modification, alongside established, low cost efforts (e.g., window screens) to prevent human contact with the disease-carrying mosquitoes will pay off.