What is the new potentially deadly mpox strain detected in the UK?

The strain, known as Clade Ib, emerged in the Democratic Republic of the Congo (DRC) in August this year.

The UK Health Security Agency (UKHSA), the government agency tasked with protecting public health, has said the case was detected in London but the risk to the UK population currently remains low.

– How did the infection occur?

The person involved had been on holiday in Africa and travelled back to the UK on an overnight flight on October 21.

They developed flu-like symptoms more than 24 hours later and, on October 24, started to develop a rash which worsened in the following days.

The person attended an emergency department in London on October 27, where they were swabbed, tested and sent home to isolate while waiting for the results.

They have now been transferred to the Royal Free Hospital high consequence infectious diseases unit for treatment.

Fewer than 10 people who are thought to have come into contact with the patient are initially being traced, the UKHSA said.

– What is Clade Ib and is it dangerous?

The UKHSA said existing evidence suggests Clade Ib causes more severe disease than Clade II, another mpox strain.

The UK case comes nearly three months after the World Health Organisation (WHO) declared outbreaks in Africa a global emergency.

– What are UK officials saying?

The UKHSA said it is working closely with the NHS and academic partners to determine the risks to public health.

It said Clade Ib will be managed as a high consequence infectious disease while scientists learn more about the virus.

– How is the UK dealing with the new infectious strain of mpox?

The agency said it is “still working” on the number of people it may have to contact trace in relation to the first UK case.

The UKHSA said the country has an existing stock of mpox vaccines and last month announced further vaccines are being procured to support a routine immunisation programme.

Professor Susan Hopkins, chief medical adviser at the UKHSA, said testing is being prioritised in London, Manchester and Brighton – areas where there are high proportions of gay and bisexual men attending sexual health clinics.

– What is mpox?

Mpox (formerly known as monkeypox) is a viral infection that spreads through close person-to-person contact and was first detected in the DRC in 1970.

Like many diseases caused by a virus, mpox has different types or “clades”.

There are two major clades of mpox, known as Clade I and Clade II.

Clade II mpox has been present in the UK since 2022.

Clade Ib mpox has been widely circulating in the DRC in recent months and there have been cases reported in Burundi, Rwanda, Uganda, Kenya, Sweden, India and Germany.

As of early September, more than 600 deaths from the virus had been reported.

– What are the symptoms of mpox and how does it spread?

Mpox is passed on through close physical contact, including during sexual contact, kissing, cuddling or holding hands.

There is also a risk from contact with bodily fluids such as saliva or snot; contact with bedding or towels or clothing; and a possibility of spread through close and prolonged face-to-face contact such as talking, breathing, coughing, or sneezing.

Symptoms include a high temperature, headache, muscle aches, backache, swollen glands, exhaustion, joint pain and skin rash or pus-filled lesions which can last two to four weeks.