A new study published Thursday warns that tiger mosquitoes are increasingly spreading to Europe because of climate change, raising the risk that tropical diseases such as dengue and chikungunya become endemic across the continent.

Nearly half the global population is now at risk of contracting dengue and chikungunya, which were once limited to the tropics, due to the warming planet. Both viruses, transmitted by mosquitoes, can occasionally be fatal. The symptoms include a high fever, headache, body aches, nausea and rash.

The tiger mosquito, in particular, is venturing further north as global temperatures rise due to man-made climate change.

The study, published in The Lancet Planetary Health, examined how climate and other factors have influenced the spread of dengue and chikungunya in Europe over the past 35 years. It found that outbreaks have become more frequent and severe since 2010, in line with rising temperatures.

“Our findings highlight that the EU is transitioning from sporadic outbreaks of Aedes-borne diseases towards an endemic state,” the study said.

In 2024, the hottest year on record, a total of 304 dengue cases were reported in the EU — “a historic peak compared with the combined total of 275 cases in the previous 15 years,” the study said.

Countries like Italy, Croatia, France and Spain have all experienced outbreaks, the study said, adding: “The trend suggests a progression from sporadic cases towards endemicity in these countries.”  

In June last year, the European Centre for Disease Prevention and Control found there were 130 locally acquired cases of dengue in the EU/EEA in 2023, compared with just 71 in the 10-year period between 2010 and 2021.

According to the study, under worst-case climate scenarios, the spread of dengue and chikungunya could increase to five times the current rate by 2060.