Thailand confirms first case of recent, deadlier Mpox strain, clade 1b

Health officials in Thailand said Thursday they had confirmed a case of the mpox variant that prompted the World Health Organization to declare a global health emergency. It is the second time the recent and deadlier variant has been found outside Africa.

The announcement of the case in Thailand is likely to raise concerns about a wider spread of the virus, especially after a variant was discovered in Sweden last week. Previously, the outbreak was centered in the Democratic Republic of Congo.

The version of the mpox virus detected in these latest cases is known as Clade Ib. Health officials are particularly concerned about it because it has a mortality rate of 3 percent, significantly higher than the mortality rate of 0.2 percent seen in the 2022 epidemic.

The earlier outbreak was caused by a variant called Clade IIb, which spreads mainly through sexual contact. Men who have sex with men were most at risk, but behavioral changes and vaccinations have stopped the spread.

Epidemiologists say Clade Ib spreads primarily through heterosexual sex. Another subtype, Clade Ia, spreads through household contact and contact with infected animals, in addition to sexual contact. So far, newborn children have been most at risk for this subtype.

Thai officials said Wednesday that the infected person was a 66-year-old European who had been working in an African country with an ongoing outbreak. They did not specify which country. The man, who lives in Thailand, did not have earnest symptoms.

According to health officials, the man flew to Thailand from Africa, transiting through the Middle East, and arrived on the evening of August 14. The next morning, he developed a fever and noticed miniature lumps on his skin.

Dr. Thongchai Keeratihuttayakorn, director general of Thailand’s disease control department, said Thai authorities would notify the World Health Organization. In a statement, he said that because most of those infected do not have respiratory symptoms, such as a cough or nasal discharge, the likelihood of spread is “less than with Covid-19 or the flu.”

He advised people to wash their hands with soap or alcohol-based hand sanitizer, avoid close contact with strangers, avoid staying in areas where there are outbreaks of the disease, and avoid rodents such as rats and squirrels from those areas.

Thailand’s Department of Disease Control is monitoring 43 people who were close to or had contact with the infected man, Dr. Thongchai said. None of them have shown any symptoms so far. They will be monitored for 21 days.

Anyone with a fever, rash or swollen lymph nodes should go to hospital immediately, he added.

Thailand is increasing screening of travellers returning from areas where there are known outbreaks of mpox. Such travellers will be required to register for a Thai Health Pass and undergo a screening process, according to Dr Thongchai.

The checks include repeated checks for anyone with a temperature above 36.8 degrees Celsius (98.2 degrees Fahrenheit). Health workers will also check such people for signs of a rash or lumps. Anyone with additional symptoms that match the mpox will be separated and tested. People traveling from high-risk countries are encouraged to report their own symptoms.

The authorities are preparing 60 rooms for people who need to undergo quarantine.

As of 2022, more than 800 cases of the earlier clade IIb version of mpox have been reported in Thailand. The virus, formerly known as monkeypox, can be spread through contact with infected animals or humans or through eating contaminated meat. It can also be spread through sexual contact or transmitted in utero.

A virus endemic to central and west Africa, mpox spread rapidly to more than 70 countries in 2022, prompting the World Health Organization to declare it a global health emergency in July of that year. It has since infected nearly 100,000 people in 116 countries.

Ryna Jirenuwata contributed to the reporting.