Spain is bracing for a summer potentially overwhelmed by mosquito infestations. Experts are warning of a significant increase in mosquito populations, a direct consequence of climate change and the exceptionally heavy spring rains. This development not only promises annoying bites but also an elevated risk of transmitting dangerous diseases.
The Deadliest Animal on the Planet: Mosquitoes as Disease Vectors
Jorge Galván, Director General of the National Association of Environmental Health Companies (ANECPLA), emphasizes the severe threat: “The mosquito is the deadliest animal on the planet.” Annually, mosquitoes are responsible for approximately 725,000 deaths worldwide, primarily by transmitting diseases such as dengue fever, Zika, chikungunya, and West Nile virus.
West Nile Virus: A Growing Threat in Spain
“The risk is real, and it is getting closer in our country,” says Galván. Last year alone, the West Nile virus claimed a dozen lives in Andalusia. Given the increased humidity caused by the extensive spring rains, a significant rise in cases is expected if no energetic prevention measures are taken.
Particular concern is raised by the increasing spread of invasive mosquito species in Spain. The Asian tiger mosquito (Aedes albopictus) has massively expanded its presence in recent years. The Science Media Centre Spain, a portal of the Ministry of Science, Innovation and Universities, also points out two other invasive species: the yellow fever mosquito (Aedes aegypti) and Aedes japonicus, which is currently found in the Cantabrian region.
While tiger mosquitoes and yellow fever mosquitoes are known carriers of yellow fever, dengue, chikungunya, and Zika, the common house mosquito (Culex pipiens), native to Spain, and Aedes japonicus can transmit the West Nile virus.
Dramatic Increase in Mosquito-Borne Diseases in Europe
The expansion of mosquito populations directly correlates with a boom in vector-borne diseases. The European Centre for Disease Prevention and Control (ECDC) recorded an alarming increase in autochthonous dengue infections in the EU in 2023: with 130 cases, this was almost double the previous year (71 cases) and nearly equal to the total number of cases in the period from 2010 to 2021 (73 cases). These outbreaks reflect global trends, especially in North and South America, where these diseases are much more common. This increases the risk of imported cases into Spain.
The West Nile virus poses the greatest concern in Spain, as it is endemic here and its main vector (Culex pipiens) is widespread. Although most infections (approx. 80%) are asymptomatic, nearly 20% of cases can cause flu-like symptoms. Less than 1% of infections affect the brain, leading to meningitis, encephalitis, or acute flaccid paralysis.
Climate Change and Human Activities Fuel the Mosquito Plague
The expansion of the geographical distribution of these mosquitoes is directly linked to climate change and the global temperature increase, as well as human activities. Roger Eritja, entomologist and head of entomology at the Citizen Science project Mosquito Alert, explains that “we transport mosquitoes in our commercial activities and leisure travel.” Additionally, human habits such as leaving small domestic water accumulations in watering cans or canisters facilitate the breeding of tiger mosquitoes.
The activity period of these animals is also increasing. Tiger mosquitoes have already been observed in spring and even during autumn-winter months. An unusually early case of the West Nile virus was detected in a child in Andalusia in March of last year, breaking the usual pattern of the vector and the disease.
Where Are Mosquitoes Distributed in Spain?
According to current data, the tiger mosquito has established itself in the east, south, and center of the Spanish peninsula, with isolated specimens sighted in Galicia and the Canary Islands. The yellow fever mosquito is no longer widespread in Spain, although it appears sporadically and has been detected in areas of the Canary Archipelago in recent years. Finally, the Japanese mosquito (Aedes japonicus), a carrier of the West Nile virus, has been established in the Cantabrian area since at least 2018.
Prevention Measures Are Crucial
Although some vaccines exist to protect against mosquito-borne diseases such as yellow fever, dengue fever, or chikungunya, these are generally reserved for residents or individuals traveling to high-incidence areas. Currently, they are not used to control outbreaks within the European Union.
To protect oneself individually, the following precautions are recommended:
- Wearing long-sleeved clothing and long pants.
- Using mosquito repellents.
- Using mosquito nets.
- Using air conditioning.
These measures should be maintained for up to three weeks after traveling to areas where Aedes mosquitoes are present, to prevent the risk of secondary transmission by infected individuals.
Furthermore, it is essential to avoid the accumulation of stagnant water in pots, buckets, drinking fountains, tarps, etc. Containers storing water should be covered to eliminate mosquito breeding grounds.
