The latest war against skeeters

Z ika seems to have arrived in Central and South America overnight, but it cannot be expected to leave as fast. Ending this public health emergency will require a persistent assault on the mosquitoes that carry the virus.

It’s painstaking work that has to proceed on two fronts, in the laboratory and on the streets: not just cleaning all the trash and other reservoirs of standing water where mosquitoes lay eggs, but developing new scientific tools and techniques, including advanced insecticides and genetically modified insects.

Given the size of the challenge, it may be motivating, if also a bit frustrating, to recall that a similar push in the 1950s and ’60s largely eliminated in the Western Hemisphere the mosquito that now carries Zika. By the ’70s, though, public health officials had let down their guard. For the people-loving

Aedes aegypti mosquito (which also transmits dengue and yellow fever), this created an opportunity to return and thrive as never before.

Getting rid of the mosquitoes will be harder this time around, and only in part because the world has grown denser and more connected. Mosquitoes have also developed resistance to the insecticide DDT. And in the half-century since Rachel Carson’s book Silent Spring warned of DDT’s health dangers, insecticide development has stalled. New compounds are needed that, like DDT, can be sprayed on walls and curtains and are effective for as long as six months.

Another approach is to tamper with mosquito biology. It’s possible, for example, to infect mosquitoes with bacteria that prevent them from transmitting dengue and other viruses, probably including Zika. Males (which don’t bite people) can be treated in this way and released into the environment, so the bacterial infection spreads.

Male mosquitoes can also be sterilized or genetically modified (quite safely) so that they cannot successfully reproduce. This strategy is being tested in Brazil and other countries with impressive results. Even before genetically modified mosquitoes are ready for widespread use, they could be deployed in the worst-affected areas.

Relentless mosquito-control efforts, along with new vaccines against Zika, can eventually bring this outbreak under control, even if they can’t vanquish mosquito-borne infections altogether.

The fight between human and insect is never-ending. The only realistic goal is to forever maintain the upper hand.