A mosquito-borne disease is spreading as the planet warms

Unlike her stealthy, malaria-spreading cousin, the female Aedes aegypti signals her approach with an exasperating drone. Her bite is far worse than her buzz. If she carries a flavivirus pathogen, her victim can be infected with dengue fever. Most infections pass without symptoms, but an unfortunate few are racked with “breakbone fever”, which causes severe joint pain, haemorrhage and, occasionally, death. The after-effects, which are poorly understood, include fatigue and cognitive impairment. Aedes is so plentiful that the United States Centres for Disease Control and Prevention reckons 100m people around the world fall sick with dengue every year.

The number of people contracting dengue has risen dramatically. In 2000 about 20,000 people died of it, according to the World Health Organisation (WHO). This year at least 40,000 will perish. By contrast, between 2000 and 2022, deaths from malaria declined by 30%, the WHO says.