Climate change raises dengue risk in Europe




Higher global temperatures and greater temperature variation due to climate change could increase the epidemic potential of the dengue virus in Europe, a new study indicates.

The research, published online in EBioMedicine, “maps dengue epidemic potential in Europe and identifies seasonal time windows when major cities are most conducive for dengue transmission from 1901 to 2099.” The investigators examined the effects of temperature on the vectorial capacity of Aedes mosquitoes. They used historic and present climate data and vector surveillance data as well as various climate-change scenarios as the basis for their projections.

Dr. Jing Liu-Helmersson Umeå University

Dr. Jing Liu-Helmersson

“Although Europe currently does not have a sufficiently high DEP [dengue epidemic potential] year round, increasing periods with higher temperatures and greater temperature variation in the future due to climate change could elevate DEP along a south to north gradient,” wrote Dr. Jing Liu-Helmersson of the department of public health and clinical medicine at Umeå University, Sweden, and her coauthors. Comparing climate data across two centuries, Dr. Liu-Helmersson and her colleagues found a slow increase in the intensity and duration of dengue transmission over the past century, and more rapidly changing trajectories projected in the 21st century with the rate of change depending on the level of greenhouse gas emissions.

Compared with tropical regions where dengue is endemic, the authors said Europe shows “pronounced seasonality and geographical heterogeneity.” Still, they wrote, the vectorial capacity (VC) of Aedes mosquitoes during summer, although low, “is currently sufficient for dengue outbreaks in Southern Europe to commence – if sufficient vector populations (either Aedes aegypti and Aedes albopictus) were active and virus were introduced.” More ominously, the researchers found that – by the end of this century – the DEP for A. aegypti could expand to Northern Europe and extend to up to 8 months in Southern Europe under the highest emission pathway. Under the lowest emission pathway, it could expand to Nice and Paris for A. aegypti from Southern European cities. For A. albopictus, the DEP could expand to significant parts of Central Europe.

“Dengue epidemic outbreak is a complex process involving many factors, with mean temperature and diurnal temperature range just being two of many,” Dr. Liu-Helmersson and her associates said. “Our findings illustrate that besides vector control, reducing greenhouse gas emissions is very important in reducing DEP for Europe especially toward the latter half of this century.”

Read the complete study in EBioMedicine (doi:10.1016/j.ebiom.2016.03.046).

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