Thailand has announced its first confirmed case of a new, potentially deadlier strain of Mpox – the first in Asia, and second outside of Africa.

According to Thailand’s Department of Disease Control, the infected 66-year-old European man arrived in Bangkok from an unnamed African country on 14 August.

He began displaying symptoms the next day, and immediately went to hospital. It has since been confirmed he had contracted Mpox, and in particular the strain known as Clade 1b.

At least 450 people have died from Mpox in an outbreak centred in the Democratic Repulic of Congo which started last year.

It has since spread to a number of nearby countries – including Burundi, Kenya, Rwanda and Uganda, all of which were previously unaffected by Mpox.

Now a more worrying strain of Mpox called Clade 1b has been identified in the east of the DRC, which is being spread along the border and into neighbouring countries.

Sweden was the first place outside of the African continent to confirm a case of Clade 1b a week ago. The infected man had also recently travelled to an unnamed African country, Sweden’s public health ministry said at the time.

The infection in Thailand is the first confirmed case of Clade 1b in Asia.

Mpox is transmitted through close contact, such as sex, skin-to-skin contact and talking or breathing close to another person – but it is nowhere near as infectious as other viruses like Covid and measles.

But the spread of the new variant and its high fatality rate in parts of Africa has sparked concern among scientists, and led the World Health Organization (WHO) to declare it a public health emergency of international concern.

Outbreaks can be controlled by spreading awareness of the disease, tracking close contacts and preventing infections with vaccines, though these are usually only available for people at risk or those who have been in close contact with an infected person.

Vaccines in Africa are in short supply, but there are plans for millions of doses to arrive in the DRC in the next week or so.

In Thailand, the Department of Disease Control has tracked down some 43 patients who were sitting in the rows near the unidentified man, and those who met him after he landed.

They will all be monitored for 21 days.

Thailand is also requiring people travelling from 42 “risk countries” to test on arrival.

Mpox causes flu-like symptoms and skin lesions. For most people, it’s a mild illness but it can be fatal.

The new strain spreading in central Africa is thought to be more deadly than previous ones – with four in 100 cases leading to death. Mpox is most common in the tropical rainforests of West and Central Africa and there are thousands of infections every year.

Another strain – Clade 2 – which is far milder, caused a global public health emergency in 2022. There are still cases of that Mpox strain in many countries.