The first case of monkeypox in Hertfordshire has been confirmed by the county council, as UK numbers rose to 71.
Officials said one positive case has been identified and health workers were contacting anyone who has been in close contact with them.
They did not reveal where in the county the case had been found, but added the resident had been "extremely prompt and proactive in seeking clinical attention".
The UK Health Security Agency (UKHSA) said on Tuesday afternoon there were now 71 confirmed cases in the UK of monkeypox - a rise of 14 cases on the previous day's total.
Health officials stressed the risk to the UK population “remains low” but it urged anyone with unusual rashes or lesions on any part of their body to contact NHS 111 or their local sexual health service.
UKHSA said a “notable proportion” of the cases identified have been among gay or bisexual men who have sex with men.
A spokesperson for Hertfordshire County Council said: "We can confirm that a positive case of monkeypox has been identified in Hertfordshire. Close contacts are being contacted and are being given the appropriate health information and advice.
"Our resident was extremely prompt and proactive in seeking clinical attention, and we wish them a full and speedy recovery.“This disease is not specific to any particular gender, sexual orientation or ethnicity and it is most likely to be transmitted via close physical contact."
The council has urged people who have recently travelled to West Africa, and gay and bisexual men to be aware of unusual rashes or lesions especially on their faces or genitals and to contact NHS 111 if they have any concerns.
The spokesman said plans were in place to ensure people could access support and treatment, contacts could be traced and offered protection, including vaccination, where necessary.
The council added: "The infection can be distressing but is mild and rare."
Health Secretary Sajid Javid said on Friday the UK government was purchasing stocks of a vaccine effective against monkeypox, after having held talks with G7 nations.
Dr Susan Hopkins, chief medical adviser at the UKHSA, said: “We are continuing to promptly identify further monkeypox cases in England through our extensive surveillance and contact tracing networks, our vigilant NHS services and thanks to people coming forward with symptoms.
“If anyone suspects they might have rashes or lesions on any part of their body, particularly if they have recently had a new sexual partner, they should limit their contact with others and contact NHS 111 or their local sexual health service as soon as possible, though please phone ahead before attending in person.”