UK: Widespread rise in mosquito-borne diseases predicted due to climate change

Many parts of the UK could soon see an upsurge in chikungunya, dengue fever and West Nile virus brought on by climate change, warn health experts from the Emergency Response Department at Public Health England.

Disease-carrying mosquitoes could become widespread across large parts of Britain within the next few decades as the climate becomes increasingly mild, they said.

The diseases, which are transmitted by insects such as mosquitoes and ticks, are on the rise and have already spread into new territories across Europe over the past decade (eg, malaria in Greece, West Nile virus in eastern Europe and chikungunya in Italy and France).

While freezing temperatures in high latitudes kill the mosquito's larvae and eggs, the rising temperatures make the climate mild and enable the Asian tiger mosquito (Aeded albopictus) to survive across large parts of England and Wales within decades.

Just a 2°C rise in temperature could extend the mosquito's activity season by one month and the geographical spread by up to 30% by 2030, says the review.

More rainfall and warmer temperatures could provide ideal conditions for the Asian tiger mosquito to breed and expand into the UK, particularly southern England.

Professor Steve Leach from the PHE said: "We are not suggesting that climate change is the only or the main factor driving the increase in vector-borne diseases in the UK and Europe, but that it is one of many factors including socioeconomic development, urbanisation, widespread land-use change, migration, and globalisation that should be considered. Lessons from the outbreaks of West Nile virus in North America and chikungunya in the Caribbean emphasise the need to assess future vector-borne disease risks and prepare contingencies for future outbreaks."

Climate change models predict suitable temperatures for one month of chikungunya virus transmission in London by 2041, and up to three months in southeast England by 2071.

The recent discovery of the Culex modestus mosquito that carries the West Nile virus at a number of sites across Kent has raised concerns of transmission of the virus between infected birds and humans.

A low number of mosquitoes and the limited spread of human-biting Culex spp have prevented any human cases so far.

'Monitor tyre imports'

Writing in The Lancet Infectious Diseases journal, the experts call for more precise monitoring at airports and seaports of imported used tyres which are ideal for mosquitoes to lay their eggs.

Unusually high air temperatures and periods of excessive rainfall, as expected under climate change, have been shown to create environmental conditions favouring bacterial growth.

The shifting climate patterns have also been linked to pathogens jumping hosts to entirely new ones.

To keep warming below 2°C, the world will have to cut greenhouse gas emissions between 40% and 70% by 2050 and gradually reduce this to zero by 2100 says the IPCC. Above this threshold temperature, the effects would be disastrous.

Among the cost of inaction are the spread of infectious diseases like leishmaniasis and West Nile fever which are causing one-third of deaths around the world, according to the World Health Organization.