UK public health officials have reported a case of mpox clade 1b in England with no apparent travel history or link with previously confirmed cases.
The patient in the North East of England was diagnosed in March and contact tracing did not identify any further cases.
More work is being done by the UK Health Security Agency (UKHSA) to determine where the individual may have caught the infection, a statement said.
Spread of mpox is associated with close contact and until now the variant clade 1b cases in the UK have been in individuals with recent travel history to Africa and their household contacts.
Common symptoms of mpox include a skin rash or pus-filled lesions which can last two to four weeks and it can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.
In March, clade Ia and Ib mpox was downgraded from a high consequence infectious disease in the UK.
A review by the Advisory Committee on Dangerous Pathogens found that it no longer meets the criteria as a high consequence infectious disease defined as having a high mortality rate and a lack of available interventions.
But this should not be interpreted as meaning the infection does not have ‘public health consequence’, UKHSA said.
Healthcare staff should remain vigilant and measures to eliminate transmission in the UK include vaccination of those most at risk.
UKHSA mpox incident director Dr Gillian Armstrong said: ‘The risk to the UK population from mpox remains low.
‘The majority of people who have presented with symptoms report close physical contact, including massages, or sex prior to developing symptoms.’
Dr Jonas Albarnaz, a fellow at The Pirbright Institute, said the detection of a case without travel or contact history is ‘surprising’.
He said: ‘Public health authorities should investigate how this recent case was acquired, but it’s likely that it was acquired from another infected person, via direct contact either with skin lesions or with contaminated surfaces or objects.
He added: ‘Transmission of mpox from an asymptomatic person has been reported, but there’s limited information about the role of asymptomatic transmission in driving mpox outbreaks.
‘Zoonotic transmission (animal to human) of mpox also occurs in endemic countries in Africa, but this is an extremely unlikely scenario given the absence of an animal reservoir in the UK.’
Vaccination remains the best strategy to prevent mpox and is recommended to individuals at higher risk of infection, which include contacts of mpox cases, healthcare workers, and people with multiple sexual partners, he noted.
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