Severe monkeypox patients could be infectious for up to 10 weeks, according to scientists.
A study released by the Lancet Infectious Diseases analysed seven cases of the virus in Britain between 2018 and 2021.
The research showed one man in his 40s tested positive over 70 days after he first displayed symptoms of the disease.
One of the study's authors, Dr Hugh Adler, from the Liverpool School of Tropical Medicine, said: “It remains positive in the throat and blood for the length of the illness and maybe even longer after the rash is resolved.
"We don’t know that this means these patients are more infectious or infectious for longer, but it does inform us of the biology of disease."
The patient in his 40s was hospitalised for 39 days before being released, only for the rash to return a month and a half later. He also suffered from swollen lymph nodes.
The revelation comes after health officials confirmed 14 more cases of monkeypox in England, bringing the total to 70 since May 7.
Scotland confirmed its first case on Monday, making up a UK total of 71. No cases have been identified in Wales or Northern Ireland.
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.
Dr Susan Hopkins, chief medical adviser for 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."
UKHSA teams have been tracing high-risk contacts of those with a confirmed case and are advising contacts to isolate for 21 days.
It is also offering a smallpox vaccine to close contacts to reduce their risk of symptoms and severe illness.
