Diseases like Dengue Fever and Chikungunya are on the rise in Europe

In September 2024, A few patients showed up at the emergency room in the Italian coastal city of Fano with mysterious symptoms: rashes on hands and feet, fever, nausea, and diarrhea. Doctors sent to various trials until someone came back with good results dengue, a viral disease transmitted by mosquitoes, usually in tropical regions of the world. They tested some patients, and sure enough, they had dengue. The strange thing? None of the patients had traveled to another country where they would expect to contract dengue. The only thing they had in common was visiting a particular area of ​​Fano.

Like climate change increases the temperature throughout Europedistractions mosquitoes spreading and causing diseases that Europeans often think of when traveling to other continents. The outbreak of Fano was not the first time that dengue appeared to be spreading in rural areas of Europe, but it was much greater than previous events, with 199 cases that occurred between August and October of 2024. In the past few years, European countries have reported outbreaks of other viruses that are transmitted by mosquitoes such as chikungulling, the painful disease of West Niswe. In a tropical world, so-called tropical diseases are no longer endemic—and researchers expect that to continue.

The biggest problem here is mosquitoes Aedes albopictusknown as the Asian tiger mosquito (or tiger mosquito, as it is now found on all continents). Unlike most types of mosquitoes, they bite both day and night. Tiger mosquitoes have already been discovered by people all over the world Europeespecially in the south, and we can expect them to go north, said Riccardo Moretti, a senior researcher at the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), who has been working on tiger mosquitoes for more than 20 years.

The tiger mosquito thrives at 20 to 30 degrees Celsius (68 to 86 Fahrenheit), but can survive as low as 10 Celsius (50 Fahrenheit). “This means that currently there are already conditions that would allow the spread of the Asian tiger mosquito, even in England,” says Moretti. Currently, these conditions are limited to the hottest part of the year in northern European countries. But in the south, like in Greece, the mosquito season is getting longer. Moretti says researchers have found adults hanging around until December and reappearing as early as March; they will overwinter as eggs. “There is a concrete risk that in the next few years, we may have people who can live year-round,” says Moretti.

Currently, mosquito-borne diseases in Europe occur in late summer. This is where tiger mosquitoes are most common, and where many people return from trips. Someone unknowingly brings a disease that is not found in Europe, say, dengue, and is bitten by a tiger mosquito. Mosquitoes continue to bite other people, and the disease spreads locally. But when the weather gets colder, the mosquitoes are less and less. If the mosquito season lasts too long, many diseases can occur. Ultimately, says Moretti, there is a risk that tropical diseases such as dengue could spread to other parts of Europe, meaning that the disease is always present. “It’s very different from occasional cases of viral transmission, rather it’s dealing with the potential for transmission,” he says.

A difference of a few degrees can make a big difference. Earlier this year, a study found that what is necessary for tiger mosquitoes to transmit chikungunya. colder than he thought at first. Mosquitoes can spread the virus at 14 degrees Celsius (57 degrees Fahrenheit) rather than 16 (61 degrees Fahrenheit), meaning epidemics can occur in many European countries and for longer periods of time. “This difference of two degrees is very important when we talk about global warming,” says Sandeep Tegar, an epidemiologist at the UK Center for Ecology and Hydrology, who led the study.