Climate change 'might bring rise in UK mosquito-borne diseases'

11:00am Monday 23rd March 2015

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Of these pathogens, some (but not all) of the most extreme modelling scenarios suggest malaria could be present in the UK as early as 2030.

Climate assessment has suggested one type of mosquito that spreads dengue fever and chikungunya could theoretically live in warmer parts of the UK, and that by 2030 the climate could be even more well suited to this mosquito.

What do they say about malaria?

The researchers explain how malaria was regularly found in certain parts of the UK in the 1800s. The UK still has several species of mosquito capable of carrying the malaria parasite, albeit the less severe kind (Plasmodium vivax).

However, the researchers say rising summer temperatures could also support the development of the more severe malaria parasite (Plasmodium falciparum).

One group of researchers have modelled the effect climate change could have on P. falciparum. They estimate there will be between 1.5C and 5C increases in temperature between 2030 and 2100. Sustained transmission of the malaria parasite is still unlikely at these temperatures.

However, one of the most extreme model scenarios they looked at suggested there could be sustained transmission of the parasite (lasting at least one month of the year) in southern England by 2080 or, to a lesser extent, even as early as 2030.  

But, as the researchers say, antimalarial drugs and the UK health system should be able to minimise transmission.

What do they say about dengue fever and chikungunya?

The researchers say that since 1990, five different tropical species of mosquito have become adapted to the temperate climate of Europe. These species are potential vectors of the tropical diseases dengue, chikungunya and yellow fever.

In the past decade, there have been cases where one of these tropical mosquito species has been implicated in outbreaks of chikungunya and dengue in southern France, Italy and Croatia.

Climate change is predicted to permit the expansion of this species across Europe, including the south of the UK.

If these mosquitoes do become established in the UK, people with dengue or chikungunya who travel to the UK would then be a source of infection for the established mosquitoes.

Ongoing transmission would then depend on the local climate conditions controlling mosquito populations.

Two models suggested that by 2030-50, the climate in southern England could be more suitable for one species of mosquito that carries chikungunya and dengue.

Models also predicted transmission periods of one month to be possible in London by 2041, and one to three months of activity possible in southern England by 2071-2100.

What do the researchers conclude?

The researchers make the following recommendations about how the potential threat from vector-borne disease could be managed:

Conclusion

Overall, this review provides insights into how climate change might lead to the transmission of tropical diseases in what are currently temperate parts of the world, such as the UK. Predicting what may happen in the future can help countries make sure they are prepared for such an eventuality.

This review was informed by a search for relevant literature, but may not have captured or included all relevant studies. Most of the studies were modelling studies, which are reliant on various assumptions that may or may not turn out to be correct.

It's not possible to say with any certainty what will occur in the future. The authors also note that climate change is not the only factor affecting vector-borne diseases.

Many other factors are equally important, such as socioeconomic development and changes in how land is used. This adds to the difficulty in predicting exactly how much climate change might impact these diseases.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Summary

"Mosquitoes heading for warmer UK," Sky News reports. A new review predicts that climate change will make the UK a hospitable environment for disease-carrying mosquitoes and ticks, leading to an outbreak of conditions such as dengue fever.

Links to Headlines

Mosquitoes Heading For Warmer UK - Experts. Sky News, March 23 2015

Mosquitoes 'could bring exotic diseases to UK'. BBC News, March 23 2015

Plague of mosquitos carrying deadly diseases is headed for Britain, scientists warn. The Daily Telegraph, March 23 2015

Warmer weather means mosquitoes carrying killer diseases including dengue fever 'could be in the UK by 2030'. Mail Online, March 22 2015

Links to Science

Medlock JM, Leach SA. Effect of climate change on vector-borne disease risk in the UK. The Lancet Infectious Diseases. March 23 2015. (Article not yet online)

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