Southern Europe: Zikaausbrüche threaten in the summer

Researchers warn of increased risk of infection in the summer months

The mosquito Aedes aegypti is considered the main transmitter of the Zika virus © CDC
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Beware of holiday trips to southern Europe: This summer, mosquitoes in the Mediterranean could carry the Zika virus. Because researchers predict there is a high risk of outbreaks of viral disease in the summer months of June to August. The reason: The warm climate, the presence of the carrier mosquitoes and the influx of air travelers from epidemic areas make outbreaks very likely.

While around 40 countries around the world are already fighting the Zika epidemic, the virus reaches new areas through infected air travelers or the introduction of mosquito carrying the virus. Recently, researchers warned that the Zika virus could also be introduced into European countries.

What is the risk of outbreak?

However, the Zika virus can only stay where there are mosquitoes of the genus Aedes, which are considered to be the reservoir and main vectors of the pathogen. This is particularly the case in countries with a warm climate and mild winters - such as in the Mediterranean. Joacim Rocklöv from Umea University in Sweden and his colleagues have therefore determined the likelihood of Zika outbreaks in Europe this summer.

For their study, the researchers combined data on the monthly influx of air passengers from Zika epidemic areas in different European cities with climate data and data on the occurrence of Aedes mosquitoes. From these data, they determined if and where the establishment of the Zika virus and an outbreak of the disease is possible.

Risk areas for a Zika outbreak. Numbers above R = 1 indicate an exponential spread of the epidemic. © EBioMedicine

Outbreaks along the Mediterranean coast

The result: "The incipient summer of the Northern Hemisphere increases the risk of epidemics of Zika virus in Europe, " the researchers said. Especially along the Mediterranean coast in Spain, France, Italy and the Balkans, the outbreak of Zika epidemics is very likely. display

"The presence of established Aedes populations, the warm climate and the particularly high influx of air passengers to Europe in the summer are a combination of three that make southern Europe fertile ground for the Zika virus, " explains Rockl v. "The warm summer climate increases the frequency of mosquito bites, accelerates the multiplication of the virus and thus also the risk of transmission."

Big danger in July and August

According to forecasts, the risk of outbreaks and infection for visitors to the Mediterranean coast will increase slowly in June, reaching its peak in July and August. In some places, the number of local zika cases could even increase exponentially, according to the calculations.

The main culprit is in most cases the Asian Tigermcke (Aedes albopictus), which has now spread to Central Europe. Even in southern Germany there is a first population. Occasional summery Zika outbreaks and falls in the Upper Rhine Valley therefore do not exclude Rockl v and his colleagues. (EbioMedicine, 2016; doi: 10.1016 / j.ebiom.2016.06.009)

(Umea University, 13.06.2016 - NPO)