Travellers are being warned about mosquito bites on holiday after a rise in chikungunya infections in people returning to the UK.
The UK Health Security Agency (UKHSA) also said the first cases of the emerging oropouche virus had been recorded.
Chikungunya typically causes sudden fever and joint pain, which can be debilitating, and lasts from a few days to weeks.
The name comes from a word in a Tanzanian language meaning "that which bends up", owing to the joint pain associated with it.
Most people recover but in some cases the symptoms can last several months or even years.
It's spread by mosquito bites in tropical and subtropical regions, and most of the 73 cases reported in the UK so far this year were in London and linked to travel to Sri Lanka, India, and Mauritius.
Only 27 cases were reported in the same January to June period last year.
Chikungunya can't spread directly from person to person - so if someone becomes ill in the UK, they can't pass the infection on, and the mosquitos responsible aren't present here.
Dr Philip Veal, consultant in public health at the UKHSA, said it can be a "nasty disease" and the increase in cases was "worrying".
"It is essential to take precautions against mosquito bites when travelling," he said.
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"Simple steps, such as using insect repellent, covering up your skin and sleeping under insecticide-treated bed nets can greatly reduce the risk."
Chikungunya is mainly found in Asia and Africa, but cases have been reported in Europe and North America this year.
Two vaccines to guard against the infection are available in the UK from private travel clinics.
The first cases of the Oropouche virus have also been confirmed in Britain, according to the UKHSA.
It's spread by midge and mosquito bites and the three cases are all linked to travel to Brazil.
Oropouche was first identified in Trinidad and Tobago in the 1950s and had been mainly confined to the Amazon area.
However, cases have been increasing since 2023 and have shown up in places such as the Dominican Republic, Cuba, and Peru.
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Symptoms include fever, headache, muscle and joint pain, nausea and vomiting.
Anyone who gets such symptoms after being in Central and South America or the Caribbean is advised to get urgent medical advice.
Most people recover on their own, but it can cause severe disease in the very elderly or those with a weak immune system.
(c) Sky News 2025: Mosquito bite warning after rise in chikungunya cases in travellers returning to UK
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