The number of people who succumb to the disease has been rising for two decades
For the second time in five years, Brazil’s army is building field hospitals in the capital, Brasília. The tents are accommodating a surge of patients from swamped emergency departments, as millions of Brazilians succumb to dengue fever that is spreading across the country. As with covid-19, the last disease to prompt the construction of field hospitals, many dengue infections are asymptomatic. The one-in-four people who do fall ill can suffer for several weeks with a painful condition known as break-bone fever. Unlike covid-19, the virus causing this wave of illness is carried by mosquitoes. As the climate warms, their range is expanding and the number of people they infect is increasing (see charts).