Global warming drives up European dengue risk

Mosquito-borne disease could be widespread by end of century

Global warming will drive the spread of dengue into higher latitudes in coming decades.
Global warming will drive the spread of dengue into higher latitudes in coming decades.

Staff Report

Rapidly warming global temperatures could spur epidemics of mosquito-transmitted dengue across wide parts of Europe by the end of the century, according to researchers with Umeå University in Sweden.

Along with the fact that disease-bearing mosquitoes will expand their range in a warming world, the scientists also found that, in general, climate change increase virus reproduction and transmission, and the rate in which the female mosquitos bite. As a result, a warmer overall climate extends the seasonal window of opportunity for mosquitos to transmit dengue fever.

“In the midst of warming temperatures on the European continent and a number of complex factors such as increased travel and trade, Europe now finds itself at an elevated risk of mosquito-borne epidemics such as dengue fever,” said Jing Liu-Helmersson, researcher at Umeå University’s Department of Public Health and Clinical Medicine and main author of the article.

The study, published in EBioMedicine, used historic and present climate data, vector surveillance data and various climate change scenarios to determine dengue epidemic risks in Europe based on modest to severe warming projections.

The findings include:

  • Current vectorial capacity indicates that dengue epidemics are possible in summer in areas of Southern Europe where Aedes mosquitos are present.
  • Future climate change will intensify vectorial capacity and shift the risk areas northward while prolonging the seasonal window.
  • By the end of the century, seasonal dengue outbreaks could emerge in much of Europe where Aedes mosquitos are present.

The Umeå University researchers concluded that Aedes mosquitos are likely to become a fixture in Europe, based on several factors. Historically, Aedes mosquitos were present in many European countries during the first half of the 1900s. The main dengue vector – Aedes aegypti – has recently been documented in Russia and Georgia. And current surveillance indicate that the secondary dengue vector, Aedes albopictus, are present in much of Southern Europe and as far north as the Netherlands.

“The 2012-2013 dengue outbreak in Madeira was a wakeup call for Europe to act,” said Jing Liu-Helmersson. “More effective vector control will certainly be crucial to reduce the risk of dengue in Europe. But this is not as easy as it sounds. In Singapore, for example, is proving difficult to control Aedes mosquitos even with readily available resources. More importantly, however, our findings illustrate that mitigating greenhouse gas emissions to curb global warming will be just as crucial.”

About dengue: a growing global health concern

  • According to the WHO, dengue is the world’s most rapidly spreading viral infection in the last 20 years.
  • Around 100 countries are considered endemic, though countries in Southeast Asia and South America are hit disproportionately.
  • There are many as 390 million new viral infections per year and about 2.5 billion people are at risk of being infected, mainly in the tropics and sub-tropics.
  • Dengue fever is a big burden on health care in affected countries.
  • Since the Aedes mosquitos carrying the virus are active during the day, and children generally do not have immunity, school children are the most exposed group.

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