Aggressive, disease-spreading mosquitoes could plague London every summer by the middle of this century, researchers have warned.
According to a preprint from modellers in the UK, US and Israel, Britain’s capital city will become hospitable for Aedes aegypti – the “yellow fever mosquito” – sooner than thought. The blood-sucking insects also carry diseases including dengue, Zika and chikungunya.
The new research takes into account natural variability in climate – as well as human-driven warming – for the first time, and predicts that the insects will establish themselves in London for between one and four months a year by 2060, and up to five months by the end of the century.
It will not be the first time insects have caused disease and death in London. Malaria was common along the River Thames until the middle of the Victorian era, especially in marshland areas to the south east of the capital. It was likely spread by the native Anopheles atroparvus, and was stamped out as drainage and housing conditions improved.
But climate change is bringing the threat of mosquito-spread pathogens back.
Holiday hotspots in southern Europe could be even worse hit than the UK, with the Aedes aegypti mosquitoes potentially able to survive year round in southern Spain, Italy and Croatia by the end of the century.
Yellow fever mosquitoes have already been found in Cyprus and their cousin, the tiger mosquito, Aedes albopictus (which survives cooler temperatures) is now well established in 13 European countries, including France, Switzerland, Greece and Spain.
When natural climate variability is taken into account, the worst-case scenarios are concerning, said Dr Robin Thompson, an associate professor of mathematical epidemiology from St Hilda’s College at the University of Oxford, and co-author of the report.
“Different parts of the climate system interact with each other, and small changes in those interactions [known as natural climate variability] make quite a big difference in temperature and rainfall,” he told The Telegraph.
“When we include that in the models, you see a variation that wasn’t there before … which shows we can plausibly have situations where the mosquitoes are present, and can lead to more disease, much sooner than we expected.”
But while much of the world will become more appealing for the Aedes aegypti, tropical regions near the equator could become too hot for the species to survive. This could trigger a significant shift in terms of the regions where pathogens such as yellow fever, Zika and dengue present the biggest threat.
The latest research comes as dengue is causing havoc across the world. Globally, some 400 million people are infected each year with dengue – dubbed ‘break-bone fever’ because severe joint pain can be one of the symptoms – and at least 100 million become ill each year.
Although cases are generally mild, it exacts a heavy toll on health systems, with 500,000 people hospitalised annually. Between 20,000 and 40,000 of these patients die.
This year has seen major outbreaks in much of Asia and South America, with Sri Lanka, Peru and Bolivia among those badly hit.
Bangladesh is also struggling with an outbreak that has broken many grim records. On Monday alone, the country reported 3,084 new dengue cases and 17 new deaths, taking the total tally this year to more than 170,000 infections and 800 fatalities.
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