In the Americas alone, almost 10.4 million suspected cases of dengue, a mosquito-borne viral disease, were reported to the World Health Organization in 2024 as of the first week of July, an increase of 232% compared with the same period the year before.

Peru is a case in point. When torrential rains started to fall there in 2023, a record-breaking dengue epidemic exploded shortly afterward. The case count is estimated at well over 100,000 so far this year.

And dengue isn't just stalking the Americas.

Bangladesh, Burkina Faso, Chad, Nepal, Sri Lanka and Vietnam are among the countries now registering uncharacteristically high numbers of cases of the disease. Many are struggling to get epidemics under control.