When health official Tatiana Marrufo visited a colleague in Mozambique’s Manica province this year, she was surprised by what he reported: there had been an increase in malaria cases reported by the local health system.

The inland highland region in the west of the country has traditionally had few cases of the parasite-borne disease. Its cooler and drier environment is a less hospitable habitat for the mosquitoes that transmit the parasite to humans in lower, hotter and wetter coastal parts of the country.

“He said they had not prioritised the province for indoor spraying with insecticides, because in the past we didn’t have [many] cases,” explains Marrufo, head of Mozambique’s Central Office of the National Observatory of Health — referring to the typical, but relatively costly, prevention technique. “But the climate is changing, and creating the conditions to have more mosquitoes.”