Tropical cyclones trigger malaria spikes in Madagascar
New research highlights the need to strengthen malaria control in climate-vulnerable regions.
- 18 July 2025
- 3 min read
- by Linda Geddes
As climate change drives more extreme weather events, new research reveals how tropical cyclones can fuel surges in malaria infections, potentially derailing disease control efforts in vulnerable countries like Madagascar.
Positioned off the south-eastern coast of Africa, Madagascar is often the first major landmass to be hit by tropical cyclones that form over the warm waters of the Indian Ocean. In recent months, the country has endured a series of intense storms, with three successive cyclones bringing torrential rains that flooded buildings and damaged health infrastructure.
“Storms have caused repeated humanitarian emergencies in recent years with widespread destruction, population displacement and damage to healthcare–related infrastructure,” said Dr Benjamin Rice at Princeton University in New Jersey, US, and colleagues, who conducted the new research.
“In particular, cyclones Batsirai and Freddy destroyed more than 300 health facilities and resulted in an estimated 112,115 and 290,000 people in need of immediate humanitarian assistance in 2022 and 2023.”
Cyclone hotspots
As well as damaging health infrastructure more generally, such events can also impede access to malaria prevention and treatment. Given that cyclones are anticipated to become more common, understanding their impact on malaria control is critical – particularly in countries with a high malaria burden, such as Madagascar – yet data remains scarce.
To better understand this relationship, Rice and colleagues analysed data from a study involving 500 households in the country’s Mananjary district, located on the south-eastern coast of Madagascar. Between July 2021 and April 2023 household members were repeatedly tested for malaria – both before and after cyclones Batsirai and Freddy – which enabled the researchers to assess how well malaria interventions held up during these events. Those who became infected were offered treatment.
The research, published in Science, found that tropical cyclones lead to sharp spikes in malaria infections and reinfections – particularly in children, where up to half of school-age kids and more than a third of younger children were infected in high-transmission areas in the two months after cyclones Batsirai and Freddy.
Equipped with these estimates, the researchers also modelled what might happen if malaria prevention efforts, including expanded testing and use of antimalarial drugs, were stepped up or disrupted during cyclone seasons.
“We find that the risk of malaria infection [and reinfection] is sufficiently high after tropical cyclones in Madagascar that the disruptions to public health activities accompanying such events pose a considerable threat to progress in disease control,” the study authors said.
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A role for vaccines?
Although Madagascar hasn’t introduced malaria vaccines into its routine immunisation programme, the researchers also evaluated the impact that vaccination might have on bridging periods of vulnerability caused by cyclones. They found that vaccination could lead to a substantial reduction (around 50%) in the frequency of symptomatic malaria in the aftermath of such disasters – although they cautioned vaccines were unlikely to significantly reduce malaria transmission if used alone.
Neither should vaccines divert attention or resources from other critical interventions, such as distributing bed-nets during periods of population displacement, reinforcing health facilities to withstand storm damage, and developing prophylaxis strategies that can withstand severe weather disruption, they said.
