Climate change is meaning mosquito-borne diseases, such as malaria and dengue, are expanding rapidly, with more than half the world’s population now at risk, an expert has warned.
Professor Rachel Lowe, who leads the global health resilience group at the Barcelona Supercomputing Center in Spain, is due to present a paper this weekend to a European Society of Clinical Microbiology and Infectious Diseases (ESCMD) summit in Barcelona about the changing global threat of such ‘vector-borne’ diseases.
She will emphasise how better early warning systems are needed to tackle this almost global phenomenon.
Mosquito-borne disease outbreaks are set to spread across currently unaffected parts of northern Europe, Asia, North America and Australia over the next few decades, she has forecast.
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“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,” Professor Lowe will warn.
“The stark reality is that longer hot seasons will enlarge the seasonal window for the spread of mosquito-borne diseases and favour increasingly frequent outbreaks that are increasingly complex to deal with.”
Previously, dengue (spread by mosquitoes that bite during the day) was largely confined to tropical and subtropical regions because freezing temperatures kill the mosquitoes’ larvae and eggs.
However, longer hot seasons have enabled dengue to become the most rapidly spreading mosquito-borne viral disease in the world.
Nine of the 10 most hospitable years for dengue transmission have occurred since 2000, allowing mosquitoes that carry dengue to invade 13 European countries, with local spread of the disease seen in France, Italy, and Spain in 2023, the ESCMD has said.
The number of dengue cases reported to the World Health Organization has increased eight-fold in the last two decades, from 500,000 in 2000 to more than five million in 2019.
Professor Lowe will explain how her recent research on climate extremes in the Caribbean found that drought conditions followed four to five months later by warmer-than-usual temperatures and excessive rainfall increases the chances 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 will say.
“Lessons from previous outbreaks underscore the importance of assessing future vector-borne disease risks and preparing contingencies for future outbreaks.”
Projections suggest that if global warming can be limited to the ambitious goal of 1°C, the population at risk of malaria and dengue is expected to increase by an additional 2.4 billion people by 2100, relative to 1970-1999.
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However, if the current trajectory of high carbon emissions and population growth continues, double the number of additional people – 4.7 billion – will be affected by dengue and malaria by the end of the century, the ESCMD has added.
