Two more cases of a new strain of mpox have been detected in the UK, officials say.

Last week, the UK Health Security Agency (UKHSA) said a single case of the mpox virus variant Clade 1b had been confirmed in London.

The agency has now announced a further two cases – in household contacts of the first case.

The latest two patients are currently under specialist care at Guy’s and St Thomas’ NHS Foundation Trust in London, it added.

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August – Mpox: What is the risk?

“The risk to the UK population remains low,” the UKHSA said.

“There has been extensive planning under way to ensure healthcare professionals are equipped and prepared to respond to any further confirmed cases.”

The UKHSA’s chief medical adviser, Professor Susan Hopkins, said: “Mpox is very infectious in households with close contact and so it is not unexpected to see further cases within the same household.

“The overall risk to the UK population remains low. We are working with partners to make sure all contacts of the cases are identified and contacted to reduce the risk of further spread.”

The first case detected in London last week was a person who had been on holiday in Africa.

They developed flu-like symptoms more than 24 hours after returning to the UK and later developed a rash which worsened in the following days.

The agency said contacts of all three cases are being followed up on and would be offered testing and vaccination as needed.

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What are the symptoms of mpox and how is it passed on?

Common symptoms of the disease include a skin rash or pus-filled lesions, which can last between two to four weeks. It can also cause fever, headaches, muscle aches, back pain, low energy and swollen lymph nodes.

Mpox, and the Clade 1b strain, is usually passed on by close physical contact, contact with infected animals, or sexual transmission.

What is mpox and has there been an outbreak in the UK before?

Mpox is a viral disease that has occurred mostly in central and western Africa.

Mpox has been endemic in parts of Africa for decades after it was first detected in humans in the Democratic Republic of the Congo (DRC) in 1970, having originally been identified in laboratory monkeys, according to the US Centers for Disease Control and Prevention (CDC).

It used to be known as monkeypox, but was renamed in 2022 by the World Health Organisation (WHO) after receiving complaints that the original name was “racist and stigmatising”.

There have been cases of mpox in the UK before, with most seen in 2022 when there was a global outbreak of a less infectious strain which spread to more than 100 countries, prompting the WHO to declare a public health emergency of international concern on 23 July 2022.

A total of 2,137 cases had been confirmed in the UK at that stage, but by 31 December 2022 that number had soared to 3,732 cases – 3,553 were in England, 34 in Northern Ireland, 97 in Scotland and 48 in Wales.

Before the spring of 2022, UK cases were usually associated with travel to or from countries where mpox is endemic, particularly in western or central Africa.

But in May that year, there was a large outbreak in the UK, mostly in men who are gay, bisexual, or have sex with other men.

A vaccination programme was launched in the UK in the summer of 2022 and closed the following July.

There have been no reported deaths due to mpox in the UK.

The UK has a stock of mpox vaccines and last month announced more were being procured to support a routine immunisation programme.