Brazil has registered a record-breaking 5.5 million cases of dengue fever this year, a mosquito-borne virus that causes high fevers, rashes, and in some cases, death.

The surge in dengue has been fuelled by high temperatures induced by both climate change and the El Niño weather pattern, scientists and medical experts say.

Brazil is a case in point. Regions once relatively free of mosquitoes, such as North America and Europe, are becoming potential hotspots for the disease. In Paris, authorities have deployed “dengue detectives” to surveil mosquitoes ahead of the Olympic Games, and health officials last year warned the UK could become home to invasive mosquitoes by 2050.