Two cases of monkeypox have been confirmed in the UK and the infections are not linked to a previous case reported earlier in the month.
The infected pair live together in the same household and one is receiving care at the expert infectious disease unit at St Mary’s Hospital in London.
The other person is isolating and does not currently require hospital treatment, the UKHSA said.
Health officials said they are investigating where and how the latest cases of monkeypox acquired their infection.
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What is monkeypox?
Monkeypox is a rare viral infection, that does not spread easily between people. Initial symptoms include fever, headache, aching muscles, backache, swollen lymph nodes, chills and exhaustion.
A rash can also develop, usually starting on the face before spreading to other parts of the body. It eventually forms a scab which falls off.
Most people recover within a few weeks but severe illness can occur in some individuals.
Dr Colin Brown, director of clinical and emerging infections at the UKHSA, said: “We have confirmed two new monkeypox cases in England that are not linked to the case announced on May 7.
“While investigations remain ongoing to determine the source of infection, it is important to emphasise it does not spread easily between people and requires close personal contact with an infected symptomatic person. The overall risk to the general public remains very low.
“We are contacting any potential friends, family or contacts in the community. We are also working with the NHS to reach any healthcare contacts who have had close contact with the cases prior to confirmation of their infection, to assess them as necessary and provide advice.”
People who might have been in close contact with either case are being contacted and given information and health advice, the UKHSA said.
The first UK case of monkeypox was recorded in September 2018 - the individual was also believed to have contracted the infection in Nigeria.