Indonesia recorded 706,297 malaria cases in 2025, the highest total in the country's history, Tanahair.net reports. Ministry of Health data show the figure rose 69% in two years, up from 418,546 cases in 2023.
The increase comes as researchers at Australia's Monash University warn that hotter temperatures and changing rainfall are opening new ground for the mosquitoes that carry malaria and dengue haemorrhagic fever. Their study, published in Science Advances this year, examined how ecological, epidemiological and socio-economic conditions interact to drive transmission of both diseases. The researchers said vector control, vaccination and cuts to greenhouse gas emissions were all needed to lower the disease burden.
"Climate change is causing rising temperatures and shifts in rainfall patterns, thereby expanding the areas suitable for Anopheles and Aedes mosquito populations to thrive," said Toby Cumming, lead researcher at the Health and Climate Initiative of the Monash School of Public Health and Preventive Medicine.
The effect of climate on transmission does not follow a straight line. It can depend on the season and differs between regions, although the overall impact tends to be broadly similar. Over the past century, malaria cases have fallen while dengue cases have grown.
Henry Surendra, an associate professor at Monash University Indonesia, said mosquito control and medical treatment had cut malaria transmission considerably. Urban growth, by contrast, is creating more breeding sites for Aedes mosquitoes and speeding the spread of dengue, a disease that still has no specific cure.
Surendra's team is working with the Ministry of Health to identify the climatic, environmental and demographic factors linked to malaria and dengue cases in high-biodiversity areas of East Kalimantan.
Cumming cautioned against complacency over malaria's long-term decline, noting that global cases have climbed 8.5% over the last decade.
"We must step up our prevention and response efforts," he said according to Tanahair.net.
Dengue vaccines and vector control methods are already in use, including the release of Wolbachia bacteria into Aedes mosquito populations to reduce the insects' capacity to transmit the virus. The researchers called for these measures to be coordinated so that both climatic and non-climatic drivers of mosquito-borne disease are tackled.