Brazilian researchers may have found key to fight off tropical diseases

Every summer seems to be the same. The Ministry of Health launches television ads asking people to prevent the proliferation of the Aedes aegypti, the mosquito that causes dengue fever. They like clean, standing water, which can easily accumulate in gardens, potted plants, and so forth. Yet every summer inevitably sees a rise in the number of dengue fever cases in the country’s warmest areas, such as Rio de Janeiro and the Northeast. Between 2015 and 2016, though, things took a turn for the worse.

The Aedes aegypti brought not only dengue fever, but also the zika virus, chikungunya, and yellow fever. The explosive zika outbreak created panic once Brazilian researchers discovered a link between the virus and cases of microcephaly in babies whose mothers were infected during pregnancy.

For years, Brazil has been losing the war against the Aedes aegypti, but research from the Institute of Biomedical Sciences of the University of São Paulo is developing a kind of male insect that could keep the mosquitoes from breeding.

This is how the technique works: by manipulating the...