A new case of a strain of mpox spreading in some parts of central and east Africa has been confirmed in Leeds.
The infected person had recently returned from Uganda where Clade 1b mpox, which used to be known as monkeypox, has been found.
This is the fifth person in England to be confirmed with this disease in recent weeks – the other four lived in the same household in London and have all recovered.
Health officials say close contacts of the Leeds case are being traced but the risk to the UK population is low.
The individual infected is being treated at a hospital in Sheffield.
Mpox symptoms often include fever, headaches and exhaustion followed by a painful rash and lesions on the body. Most people recover but it can be serious for some.
It is spread through close contact such as sex, skin-to-skin contact and talking or breathing very closely to another person.
Prof Susan Hopkins, chief medical adviser at the UK Health Security Agency, said: “It is thanks to clinicians rapidly recognising the symptoms and our diagnostics tests that we have been able to detect this new case.”
“The risk to the UK population remains low following this fifth case, and we are working rapidly to trace close contacts and reduce the risk of any potential spread,” she added.
Prof Hopkins said they would be offered testing and vaccination.
There have been cases of a milder form of mpox called Clade 2 in the UK for several years.
Cases of the more serious Clade 1 are rarer in the UK.
But UK health officials had expected to detect a small number after a new form of the virus spread in the Democratic Republic of Congo over the last year.
Clade 1b mpox has spread from DR Congo to Burundi, Rwanda, Uganda and Kenya in recent months.
That prompted the World Health Organization to declare a international public health emergency in August, which it said last week was ongoing.
However, there are some signs that the upsurge in mpox infections is reducing, according to medics working at a clinic in eastern DR Congo.
Millions of vaccines are being sent to the hardest-hit areas of east and central Africa to help control the outbreak.
Sweden, Germany, India, Thailand, Canada and the US have all seen imported cases of Clade 1b but there has been little onward spread to date.