Warmer climate spreading risk of malaria and dengue to new regions

New research from health resilience experts warns that mosquito-borne diseases, including malaria and dengue, are spreading to new regions as the planet becomes warmer, with additional 4.7 billion people around the world set to be at risk of malaria and dengue by 2100.

Parts of northern Europe, Asia, North America and Australia previously unaffected by mosquito-borne diseases will be at risk over the next few decades, researchers will warn in a presentation at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Global Congress in Barcelona.

The research estimates that the additional 4.7 billion people will be at risk of malaria and dengue by the end of this century if emissions and population growth continue to rise at current levels. This number would be halved under an “ambitious” 1°C scenario. The geographical range of diseases carried by mosquitoes has expanded to cover about half the world’s population, the research says, and will increase further as mosquito-borne diseases spread to new regions.

Professor Rachel Lowe, head of earth sciences, global health resilience at the Barcelona Supercomputing Center, says early warning systems that combine improved mosquito surveillance with climate forecasts will give communities time to prepare and protect their populations from infection.

“Researchers are developing ways to predict when and where epidemics might occur, and direct interventions to the most at-risk areas in advance,” the ESCMID says.

Lowe is leading a project using a supercomputer to understand how climate and disease transmission are linked to predict mosquito-borne disease outbreaks in 12 countries.

“By analysing weather patterns, finding mosquito breeding sites with drones, and gathering information from local communities and health officials, we are hoping to give communities time to prepare and protect themselves,” explains Lowe.

But she says the most effective way to reduce the risk of such diseases spreading to new areas will be to dramatically curb emissions.

“Global warming due to climate change means that the disease vectors that carry and spread malaria and dengue can find a home in more regions, with outbreaks occurring in areas where people are likely to be immunologically naive and public health systems unprepared,” warns Lowe.

Longer hot seasons increase the window for the spread of mosquito-borne diseases, with dengue set to become the most rapidly spreading mosquito-borne viral disease in the world, she adds.

“Nine of the ten most hospitable years for dengue transmission have occurred since 2000,” the ESCMID says, setting a path for mosquitoes carrying dengue to invade 13 European countries. Local spread of the disease was tracked in France, Italy and Spain in 2023.

Lowe carried out research on climate extremes in the Caribbean, which found drought conditions followed four to five months later by warmer-than-usual temperatures and excessive rain increased the risk of dengue outbreaks.

“Droughts and floods linked to climate change can lead to greater transmission of the virus, with stored water providing additional mosquito breeding sites,” she says, adding that El Niño events provide ideal conditions for outbreaks of mosquito-borne diseases, which also include Zika.

“With climate change seeming so difficult to address, we can expect to see more cases and possibly deaths from diseases such as dengue and malaria across mainland Europe,” Lowe says.

Early intervention will help prevent disease, Lowe says. “Efforts need to focus on enhancing surveillance with early warning and response systems similar to those seen in other parts of the world, to more effectively target finite resources to the most at-risk areas to control and prevent disease outbreaks and save lives,” she says.