In a remote village in South Africa, Paulina Mhlongo sits in the courtyard while health workers dressed in green protective suits move quickly through her house, spraying the walls with mosquito insecticide.
His teenage grandson fell seriously ill last year with malaria, a disease that kills more than a quarter of a million people each year and is experiencing a resurgence in southern Africa as the climate changes.
Before this spraying, the family's "only defense" against malaria-carrying mosquitoes was a noisy fan, said Ms. Mhlongo, a 63-year-old retiree.
His village, Calcutta, is located in the province of Mpumalanga, one of the three provinces in South Africa's malaria belt which is experiencing changes in rainfall patterns and rising temperatures that favor mosquito breeding.
Heavy rains leave puddles of water conducive to egg-laying, while warmer temperatures accelerate the development of mosquitoes and shorten the incubation period of the malaria parasite.
Malaria cases in Mpumalanga quadrupled in January compared to the previous year, according to the National Institute for Communicable Diseases (NICD).
This resurgence jeopardizes South Africa's goal of eradicating the disease by 2029.
Gauteng — the flagship province home to Johannesburg and Pretoria, and where malaria is not endemic — recorded more than 400 cases and 11 deaths in the first three months of 2026, according to the NICD.
Although most infections were imported into the province from known hotspots, these numbers are "concerning" even if the disease is not transmitted from person to person, the public health agency said.
- Rapidly expanding clusters -
Human-caused climate change has increased the likelihood and intensity of extreme weather events, while the natural phenomenon La Niña brought above-average rainfall to parts of southern Africa in early 2026, causing flooding that created more breeding grounds for mosquitoes, the group said.
Namibia reported 8,760 cases in the first four weeks of 2026, a 68% increase compared to the previous year.
Mozambique, hit by floods, recorded more than 1.35 million cases in the first six weeks of the year, a 55% increase, as well as dozens of deaths.
The outlook is not reassuring as climate volatility increases.
The increase in the number of malaria cases does not mean that the disease is spreading, said Professor Jantjie Taljaard, head of the infectious diseases department at Stellenbosch University.
On the contrary, climate change amplifies existing outbreaks and prolongs transmission periods, fueling much more intense epidemics.
"Rural areas and regions on the fringes of established malaria risk areas are the most exposed," Taljaard said.
The effects are being felt on the front line at the Cunningmoore clinic, where technicians Nicholas Skhumbane and Armstrong Mgiba are rapidly processing a steady stream of blood samples from the surrounding villages.
Working in a dilapidated laboratory, the two men, dressed in white coats and latex gloves, systematically move from one slide to another.
They add a drop of Giemsa stain — a blue-violet dye that highlights malaria parasites — before placing each sample under a microscope.
The results are returned as quickly as at Tintswalo Hospital, a modern facility located about 50 kilometers (30 miles) away.
- "Even in winter" -
For health officials, changing weather conditions are forcing them to rethink malaria control planning beyond traditionally affected areas and seasons.
“Climate change is a complex phenomenon to manage,” said Sharon Lindiwe Nyoni, head of the malaria control program at the Mpumalanga health department.
"When you plan as a department, you have to anticipate what's coming, but with climate change, everything is happening right now."
The old assumption that malaria is limited to summer is no longer valid, she warned. "Even in winter, we continue to observe cases of transmission."
According to experts, it is not only local health systems that are under strain, but also intervention efforts.
"Floods can simply prevent us from reaching communities to put control measures in place," virologist Edina Amponsah-Dacosta told AFP.
In addition to heavy rains, extreme heat poses a challenge because it can break the strict cold chain required before vaccines, which must be refrigerated, reach isolated clinics, she added.
Despite the rising number of cases, health officials say some residents remain skeptical about the safety of insecticide spraying and refuse to let them into their homes.
"It is very painful to see someone die from a disease that is preventable and, again, curable," Nyoni said.
Back in Calcutta, Mhlongo waited outside as the acrid smell of insecticide wafted out of her freshly sprayed nine-room house, which she shares with eight members of her family.
Empty beer cans littered the back of a van parked nearby, propped up on rocks – a spot that sprayers said could harbor mosquitoes.
"I'm happy because mosquitoes are a problem," said Mhlongo, serving the spraying team a homemade snack of cornmeal, sugar, and peanuts, while a neighbor's music drifted through the farming village.
