Health authorities have warned of a “worrying increase” in cases of a mosquito-borne infection in people returning to the UK from abroad.
A total of 73 cases of chikungunya were reported between January and June 2025 – more than double the 27 cases reported in the same period last year, the UK Health Agency (UKHSA) said.
Data released by the agency also revealed three cases of oropouche virus, marking the first time the virus has been reported in the UK.
Here is everything you need to know about both viruses, from symptoms to prevention and what could be behind the surge in cases.
What is chikungunya?
Chikungunya is a disease caused by a virus of the same name. It was first identified following an outbreak in Tanzania in 1952.
The name is derived from a word in the Tanzanian language Makonde, and means “that which bends up”, owing to the joint pain it can cause.
It is spread by mosquito bites, specifically from yellow fever and tiger mosquitoes, in tropical and subtropical regions.
File pic: iStock
What are the symptoms?
Typical symptoms include fever, muscle pain, nausea, fatigue and a rash.
The UKHSA says joint pain can persist for months or even years, with up to 12% of people still experiencing discomfort three years after infection.
The majority of people who become infected recover within one to two weeks without needing medical attention.
Serious complications are uncommon, and only very rare cases are fatal. Babies or elderly people with other underlying illnesses are the most vulnerable.
The two mosquitoes known to transmit the disease, yellow fever and tiger, are not currently found in the UK.
How does oropouche virus differ?
Oropouche virus is spread predominantly by midge bites rather than mosquito bites.
While bites from both insects can cause red itchy lumps on the skin, mosquito bites are generally larger and more painful, while midge bites are smaller and may last longer.
Symptoms can be similar to chikungunya, and include joint paint, headache, chills, nausea and high fever.
The UKHSA says anyone who becomes unwell with these symptoms after travelling should seek “urgent medical advice”.
A midge bit can cause oropouche virus. Pic: iStock
Where can you catch the viruses?
Regular outbreaks of chikungunya occur in Africa, Asia and the Americas, with occasional smaller instances in Europe.
The UKHSA said the majority of the 73 reported cases from the first six months of this year reported travelling to Sri Lanka, India and Mauritius. The cases were linked to local outbreaks in the Indian Ocean region.
As of last month, there have been about 240,000 cases of chikungunya – and 90 deaths – in 16 countries, according to the European Centres for Disease Prevention and Control (ECDC).
Meanwhile, all the UK cases of oropouche virus were associated with travel to Brazil.
Last year, 44 cases were reported in several European countries including Spain, Italy, France, Germany, Austria, Sweden and the Netherlands, according to the ECDC.
A worker sprays insecticide following an outbreak of chikungunya in China. Pic: Reuters
China is currently experiencing the biggest chikungunya outbreak ever documented in the country, according to Cesar Lopez-Camacho of the University of Oxford.
More than 7,000 cases have been reported since June, with 90% of those concentrated in Guangdong province, which borders Hong Kong.
How to prepare before travelling
Dr Philip Veal, a consultant in public health at UKHSA said it is “essential” for people to take precautions against mosquito bites when travelling.
“Simple steps, such as using insect repellent, covering up your skin and sleeping under insecticide-treated bed nets can greatly reduce the risk,” he said.
Checking the latest health advice on your destination before you travel is also recommended.
The LSHTM added that people can do the following to reduce exposure to mosquito and midge bites:
• Fit screens to windows and doors;
• Avoid peak activity during dusk and dawn;
• Get rid of any standing water where mosquitoes breed.
There are also two vaccines for chikungunya approved for use in the UK: IXCHIQ, for people aged 18 to 59 and Vimkunya, for individuals 12 years and older.
Both are available to buy privately from travel clinics after an assessment by a healthcare professional.
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What’s behind the increase in cases?
The number of outbreaks of chikungunya has increased since 2000, Robert Jones, an assistant professor at the London School of Hygiene and Tropical Medicine (LSHTM) said.
Mr Jones put this boom partly down to climate change and urban expansion.
Dr Yang Liu, another professor at LSHTM, said the outbreak in China is not totally unexpected, but highlights the manifestation of a known risk, as yellow fever and tiger mosquitoes have been present in the area for many years.
