Dengue spike in Europe triggers fear of more infections, deaths

Europe has seen more cases of locally acquired dengue in 2022 than the total number of cases in the previous decade, as heat waves and flooding allow invasive mosquitoes to establish themselves further north and west in the region.

The data released Thursday by the European Centre for Disease Prevention and Control (ECDC) is a stark warning that climate change, as well as factors such as migration and land-use change, appears to be contributing to the spread of mosquito-borne diseases on the Continent. The ECDC’s Director Andrea Ammon warned that Europe could see more cases and potentially deaths from diseases such as dengue, chikungunya and West Nile fever.

In 2022, there were 71 cases of locally acquired dengue, with 65 in France and six in Spain. There was also a peak in cases of West Nile virus, with 1,133 cases and 92 deaths. Most of those cases — 1,112 — were locally acquired in 11 countries, with more than 700 in Italy. It’s the highest number of cases since 2018, when a major outbreak during that year’s heat wave killed 180 people in 10 countries. 

Dengue usually results in mild or no symptoms but it can also lead to high fever, severe headache and vomiting. Severe dengue can result in bleeding from the gums, abdominal pain and, in some cases, death. The West Nile virus is usually asymptomatic but in some people can result in fever, headache and a skin rash, with severe cases potentially leading to a coma, paralysis or death.

There are two mosquitoes whose spread in Europe is most concerning: The Asian tiger mosquito, which can transmit chikungunya and dengue viruses, and the yellow fever mosquito, which can transmit dengue, yellow fever, chikungunya, zika and West Nile viruses. Ammon said that recent years have seen a spread of invasive mosquitoes to previously unaffected areas in the EU and EEA.

But establishing the cause for these increases isn’t easy. 

“Climate change and more warm weather may be contributing to the [spike] of the viruses by creating more favorable conditions for the mosquito vectors,” said Ammon. But she cautioned that climate change wasn’t solely to blame, pointing to other factors include travel, land use changes and water accessibility. 

Malaria risk

Head of the Global Fund to Fight AIDS, Tuberculosis and Malaria, Peter Sands, previously told POLITICO that malaria could come back to Europe because of climate change. Sands believes that the next pandemic is likely to be a disease that’s already among us, with climate change fueling it into a pandemic.

Europe managed to eradicate malaria through a huge postwar program of insecticide spraying, swamp draining and drug therapy. However, the Mediterranean remains entirely suitable for malaria transmission.

The latest report from the ECDC on malaria on Thursday shows that over 99 percent of the 4,800 cases in the region in 2021 were travel-related. The ECDC said that malaria “remains a risk to the EU/EEA and there is a need for continuous malaria surveillance, preparedness, and prevention in the EU/EEA.”

What’s needed, Ammon said, is more research to understand the impact of climate change on these infectious diseases as well as more research on sustainable and eco-friendly mosquito control measures. Laboratory capacity for surveillance is needed, as is raising awareness among the public, said the ECDC chief.