Europe's battle against Aedes mosquitoes: growing threat of mosquito-borne diseases

By Neha MathurJun 26 2023Reviewed by Lily Ramsey, LLM

In a recent report published on the European Centre for Disease Prevention and Control (ECDC) website, the agency described how cases of all types of mosquito-borne diseases are increasing in Europe.

Study: Increasing risk of mosquito-borne diseases in EU/EEA following spread of Aedes species. Image Credit: nechaevkon/Shutterstock.com

Background

Since the 1990s, invasive mosquitoes that colonize new territories have been increasing in Europe. Examples include Aedis mosquito species carrying dengue, chikungunya, and Zika viruses. 

Per recent ECDC data, Aedes albopictus, the well-recognized vector of dengue and chikungunya viruses, is spreading north and westwards in Europe. Likewise, Aedes aegypti (invasive), another mosquito species that transmits yellow fever, West Nile, and Zika viruses, has established itself in Cyprus and now spreading to other European countries.

Accordingly, the ECDC documented more than expected cases, including deaths, due to these viruses, especially dengue, chikungunya, and West Nile viruses, in previously unaffected geographical areas of the EU/EEA.

About the study

In the present study, researchers described that in 10 years, the Aedes species had established itself in 13 countries and 337 European regions, which implies that these regions have self-sustaining, overwintering, and reproducing mosquito populations.

Around ten years ago, i.e., in 2013, the Aedes albopictus mosquito species had established in eight EU/EEA countries, while 114 regions were affected. 

The peak epidemic year for West Nile virus infections in the EU/EEA was 2018. In 2022, 1,133 human cases and 92 deaths due to this infection occurred in the EU/EEA, of which 11 countries, e.g., Germany and Spain, reported 1,112 locally acquired cases.

Likewise, in 2022, in mainland EU/EEA, ECDC found 71 cases of locally acquired dengue, with 65 and six dengue cases in France and Spain, respectively. Of all tropical mosquito-borne diseases, dengue is endemic in >100 countries across most continents, including Africa, the Americas, Southern and Southern Eaernst Asia, and the Western Pacific region.

However, now its incidence has dramatically increased globally in recent decades. Intriguingly, Aedes aegypti causes dengue globally, and Aedes albopictus causes dengue in Europe. However, both species breed in or near human inhabitants.

Another worrisome disease caused by mosquitoes is West Nile virus disease. It commonly occurs in birds by the bite of virus-infected Culex pipiens mosquitoes. It also incidentally infects humans and other mammals, such as horses.

In humans, ~80% of West Nile fever cases are asymptomatic; however, some of the most common clinical symptoms include headache, fever, rash, fatigue, and eye pain, to name a few.

Notably, older adults and immunocompromised people are at a higher risk of developing West Nile fever, a fatal, neuroinvasive disease for which no prophylaxis or treatment is available.

Andrea Ammon, ECDC Director said…

…In recent years we have seen a geographical spread of invasive mosquito species to previously unaffected areas in the EU/EEA. If this continues, we can expect to see more cases and possibly deaths from diseases such as dengue, chikungunya, and West Nile fever. Efforts need to focus on ways to control mosquito populations, enhancing surveillance and enforcing personal protective measures.”                                                 

Conclusions

ECDC experts recommended a three-pronged strategy to mitigate and control mosquito breeding.

The first approach sustainably controls mosquito populations via eliminating their breeding ground, i.e., standing water sources, using environmentally safe larvicides, and spreading awareness in the community that mosquitoes are vectors of some extremely fatal diseases.

It is also crucial to spread awareness among the masses, healthcare personnel, and travelers, especially those visiting countries where mosquito-borne diseases are endemic.

Lastly, they recommended the use of personal protective measures to mitigate the threat of mosquito-borne diseases, e.g., insecticide-treated mosquito bed nets, mosquito repellent creams, sprays, sleeping in air-conditioned rooms, and wearing clothes that cover most body parts, especially legs, and arms.