Britons travelling abroad this summer could be at risk of deadly mosquito-borne diseases sweeping through European holiday hotspots each summer.
Mosquito season is now entering its peak months, with soaring temperatures creating ideal breeding conditions and increasing the risk of viruses such as West Nile, chikungunya and dengue fever spreading across the continent.
These have been known to trigger debilitating joint pain, paralysis, vision loss and even death.
The insects transmit the viruses by biting infected animals or people before passing the virus into humans’ bloodstream through a subsequent bite.
And the Daily Mail’s interactive map shows that more than 1,000 suspected cases of these diseases were recorded across major European holiday destinations as of last summer, including Spain, Portugal, France, Italy and Greece – a pattern experts fear could become a more frequent occurrence.
Around 38 people also died, most of them from West Nile virus infections in Italy.
Official data from the European Centre for Disease Prevention and Control shows West Nile virus is already returning this summer, with cases detected in the Italian provinces of Caserta, Florence and Verona.
Romania and North Macedonia have also reported a shared three infections.
The spread of West Nile virus is becoming an increasing concern across Europe.
First identified in Uganda’s West Nile district in 1937, the virus circulates between birds and mosquitoes, but humans and horses can become infected after being bitten by a mosquito that has previously fed on an infected bird.
Italy has recorded one case in each of Caserta in the south, Florence in the centre of the country, and Verona in the north so far this year.
Last year, nine European countries reported a total of 652 West Nile virus infections.
Italy accounted for the overwhelming majority, with 500 cases, followed by Greece with 69, Serbia with 33 and France with 20. Spain also had five.
Most infections occurred in men aged 65 and over, and more than nine in 10 patients required hospital treatment.
According to the UK Health Security Agency (UKHSA), most people infected with West Nile virus experience either no symptoms or only mild illness, including fever, headaches and a rash.
But around 1 in 150 people will develop severe complications, including sometimes fatal meningitis and encephalitis, which cause inflammation of the brain and the tissues surrounding the brain and spinal cord.
There is no vaccine or specific treatment for West Nile virus, and those aged over 50 and those with underlying health conditions – including diabetes, cancer, high blood pressure and kidney disease – are at the greatest risk of developing severe illness.
The risk of death is highest among people aged over 70.
Chikungunya also surged across Europe last summer, with 301 suspected cases recorded in France and 107 in Italy.
Globally, the virus is most common in tropical regions, particularly Brazil, where tens of thousands of infections have been reported already this year.
France, however, experienced an unprecedented outbreak in 2025, with almost 800 locally acquired cases by the end of the year after the virus was imported from an epidemic on Reunion Island.
Chikungunya is notorious for causing intense joint pain that can leave sufferers stooped over, as well as fever, muscle aches, headaches, fatigue and a rash.
Although most people recover within days or weeks, some continue to suffer debilitating joint pain or arthritis for months or even years.
Mosquito season is now entering its peak months, increasing the risk of viruses such as West Nile, chikungunya and dengue fever spreading in Europe
In rare cases, the virus can affect the eyes, brain, heart or digestive system. Serious illness is uncommon but older adults and people with underlying health conditions are at greater risk of severe complications, which can sometimes prove deadly.
Dengue fever was the least common of the three diseases in Europe last summer, with 19 suspected cases recorded in France, four in Italy and two in Portugal.
The disease is typically found in tropical regions of Africa, Asia, the Americas, the Caribbean and the Pacific, but has increasingly appeared in parts of Europe, including Croatia, France, Italy, Spain, Portugal and Madeira.
Most people experience flu-like symptoms, including a high temperature, headache, pain behind the eyes, muscle and joint pain, nausea, swollen glands and a rash.
But it can also develop into severe dengue, which can bring intense abdominal pain, persistent vomiting, rapid breathing, and blood in the vomit or stool.
The World Health Organisation estimates there are between 100 million and 400 million dengue infections worldwide every year.
Experts have previously warned that mosquito-borne diseases are becoming an increasing concern due to climate change.
Professor Rachel Lowe, from the global health resilience group at the Barcelona Supercomputing Center in Spain, has said: ‘Global warming due to climate change means that the disease vectors that carry and spread malaria and dengue [fever] can find a home in more regions, with outbreaks occurring in areas where people are likely to be immunologically naive and public health systems unprepared.
‘The stark reality is that longer hot seasons will enlarge the seasonal window for the spread of mosquito-borne diseases and favour increasingly frequent outbreaks that are increasingly complex to deal with.’
For people in the UK, the risk of catching any of these diseases at home remains very low.
Health officials say the greatest risk of acquiring West Nile virus, however, comes from travelling to countries where the virus is already circulating.
Although experts believe the threat is gradually increasing as the climate warms and Britain becomes hotter, measures are said to be in place to detect signs of transmission.
The same is true for chikungunya and dengue.
A small number of chikungunya cases are reported in the UK each year, but almost all involve travellers returning from countries in South and South East Asia where the virus is widespread.
Dengue is not transmitted in Britain either, with reported cases linked to overseas travel, mainly to Asia, Latin America, Africa and the Caribbean.
The UKHSA says: ‘In many countries, mosquito bites can spread diseases like chikungunya, dengue, Japanese encephalitis, malaria, West Nile virus, yellow fever and Zika.
‘They can result in serious illness and some may even be fatal. Avoid insect bites at all times including during the day. It is important to cover up, use repellents, [and] use nets.’
