Dengue fever cases are on the rise in Europe as climate change helps dengue-carrying tiger mosquitoes establish themselves across the continent.

In 2023, there were 130 locally acquired cases of dengue reported in the European Union (EU), a significant increase from the 71 cases in 2022, according to the European Centre for Disease Prevention and Control (ECDC).

This alarming trend is even more pronounced when looking at data from the previous decade: between 2010 and 2021, there were only 73 cases reported. ECDC Director Andrea Ammon attributes this rise to climate change, which creates more favorable conditions for invasive mosquitoes to spread into previously unaffected areas, increasing the likelihood of disease transmission.

"Climate change is creating more favorable conditions for invasive mosquitoes to spread into previously unaffected areas and infect more people with diseases such as dengue," Ammon said. "Increased international travel from dengue-endemic countries will also increase the risk of imported cases, and inevitably also the risk of local outbreaks."

Indeed, imported dengue cases are also on the rise. Over 4,900 people in Europe contracted dengue while traveling abroad in 2023, the highest number since surveillance began in 2008 and a sharp increase from the 1,572 cases reported in 2022.

The tiger mosquito, known for spreading dengue as well as chikungunya and Zika virus, was once confined to tropical regions. However, the ECDC reports that it is now established in 13 European countries: Austria, Bulgaria, Croatia, France, Germany, Greece, Hungary, Italy, Malta, Portugal, Romania, Slovenia, and Spain. While the tiger mosquito has been detected at UK ports several times in recent years, no local populations have yet been established.

Dengue fever, often referred to as "break bone fever," is a mosquito-borne viral disease that can cause severe joint pain, earning its nickname because sufferers often feel as if their bones have been broken. According to the World Health Organization (WHO), other symptoms include severe headaches, pain behind the eyes, nausea, vomiting, swollen glands, a high fever, and a rash.

While 75% of those infected show no symptoms, 1% to 5% develop severe dengue, which can be potentially fatal. Symptoms typically appear between four and ten days after infection and last for two to seven days.

With the ECDC warning that mosquito-borne diseases are likely to become more common in Europe due to climate change, it is crucial for residents in affected areas to take preventive measures. The ECDC advises removing stagnant water from gardens or balconies where mosquitoes can breed, using bed nets or window screens, and applying insect repellent.

The spread of mosquito populations in Europe is not just a concern for dengue fever. In March 2023, a person in Seville, Spain, was infected with West Nile virus. Although this was an isolated case, it highlights that transmission of West Nile virus can occur very early in the year, likely due to suitable climatic conditions.

Moreover, a type of mosquito that carries yellow fever, as well as dengue, chikungunya, and Zika, has recently established itself in Cyprus. The ECDC expressed concern over the potential for this mosquito to spread to other parts of Europe due to its significant ability to transmit pathogens and its preference for biting humans.

The increasing prevalence of dengue fever and other mosquito-borne diseases in Europe underscores the broader public health implications of climate change. As temperatures rise, many regions that were previously unsuitable for certain mosquito species are becoming habitable, facilitating the spread of diseases that were once confined to tropical and subtropical areas.

Public health authorities must adapt to this new reality by enhancing surveillance and control measures for mosquito-borne diseases. This includes investing in research to better understand the impact of climate change on mosquito behavior and disease transmission, as well as developing more effective strategies for mosquito control and disease prevention.

The rise in dengue fever cases in Europe is a stark reminder of the far-reaching impacts of climate change on public health. The establishment of dengue-carrying tiger mosquitoes in 13 European countries and the increasing number of imported cases highlight the urgent need for coordinated efforts to mitigate the spread of these diseases.

By taking proactive measures to reduce mosquito breeding grounds and protect themselves from bites, residents can help curb the spread of dengue and other mosquito-borne diseases. At the same time, policymakers and public health officials must work together to address the underlying factors driving the spread of these diseases, including climate change and increased international travel.

As the ECDC and other health organizations continue to monitor the situation, it is crucial for the public to stay informed and take necessary precautions to protect their health and the health of their communities.