Thailand records first Asian case of infectious strain of mpox

The Thai health authorities have reported the first case of infection with the mpox virus (monkeypox) 1b variant. A 66-year-old European man arrived in Thailand on August 14 from an African country. The Thai Department of Disease Control stated that the man was hospitalized the day after arriving in Thailand due to illness and fever consistent with monkeypox symptoms.

Prior to arriving in Thailand, it was confirmed that 43 people had been in close contact with the man. This comes after the Africa Centers for Disease Control and Prevention declared a public health emergency on the continent on Tuesday. The 1b variant is a more lethal strain of the virus, rapidly spreading in the Democratic Republic of Congo and has spread to at least four previously unaffected countries in Africa.

World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus said the risk of further international spread is "very concerning." The chair of the WHO Emergency Committee, Dimi Ogoina, stated, “There is a consensus that the current mpox outbreak and its escalation is an extraordinary event.” He also noted, “What we are seeing in Africa is just the tip of the iceberg, and we don’t fully understand the burden of mpox.”

Global experts are closely monitoring the situation. Mpox, formerly known as monkeypox, is a viral disease related to the now-eradicated smallpox virus. According to the WHO, it can be spread through close contact, such as touching, kissing, or sexual activity, as well as through contaminated bed linens, clothing, and needles. Initial symptoms often resemble the flu, including fever, chills, fatigue, headache, and muscle weakness, followed by a typically painful or itchy rash with raised lesions that scab over and resolve within a few weeks.

Mpox is characterized by two genetic variants, I and II. Variants are broad groupings of viruses that have evolved over decades, with distinct genetic and clinical differences. Variant II caused the global outbreak between July 2022 and May 2023, which was also declared a global health emergency. However, the new outbreak is driven by variant I, which causes more severe illness. The subtype responsible for the majority of the current spread, variant 1b, is relatively new. Dr. Daniel Bausch, senior advisor for global health security at FIND, stated, “1b has become a new mutation adapted to humans due to a variety of different factors.”

He stated that the virus typically spreads from animals to humans. However, once a mutation adapts, it can be transmitted by humans and trigger larger outbreaks. Variant 1b is new and concerning, but the current situation is further complicated by multiple overlapping outbreaks. Tedros said on Wednesday, “We are not dealing with one outbreak of one variant; we are dealing with multiple outbreaks of different variants in different countries, with different modes of transmission and different levels of risk.”

According to the US Centers for Disease Control and Prevention, some variant I mpox outbreaks have resulted in death in up to 10% of those infected, although recent outbreaks have had lower mortality rates. Variant II has a mortality rate of less than 0.2%. Certain groups, including infants, people with severely compromised immune systems, and pregnant women, are more likely to develop more severe infections. Bausch stated that surveillance of mpox remains incomplete, and there is much that still needs to be learned. “It’s a virus that’s in the environment, presumably maintained in small mammals in Africa, and we don’t have appropriate diagnostics.”

“Diagnosing mpox infection is not necessarily difficult when a lab is right next door with skilled lab workers and technology. But of course, these cases often occur in very remote areas, so trying to get samples and get them to a lab is a difficult thing.” Our understanding of transmissibility and mortality risk may be biased by limitations that tend to detect only the most severe cases. Regardless, increased transmission increases the public health burden and the number of affected individuals. Bausch stated, “It’s a disease that causes a lot of suffering and fear.”

For decades, mpox was primarily found in Central and West Africa. The vast majority of variant I cases have been from Central Africa and the Democratic Republic of Congo, and the vast majority of variant II cases have been from Nigeria. In 2022, concerns grew when cases began to spread in Europe and North America. The wider international spread was a key reason mpox was declared a global health emergency, but the current outbreak has a different geographic pattern than the one two years ago. Now, mpox is spreading to more previously unaffected countries in Africa. Although the vast majority of cases are still concentrated in the Democratic Republic of Congo, at least 13 countries on the continent have reported cases, according to the Africa Centers for Disease Control and Prevention.

On Thursday, Sweden confirmed its first case of variant I mpox, marking the first time the virus has been found outside of Africa. Bausch stated, “We’ve heard it countless times, nobody is safe until everyone is safe,” especially with international travel being so prevalent. “There are many reasons to be concerned and to act early.” He also stated that this involves equity and human rights issues. The 2022 global health emergency declaration set a precedent that equally concerning patterns of spread in multiple African countries should receive the same level of attention and concern as spread in high-income countries.

There are currently vaccines available to prevent mpox, but vaccine access is limited in Africa. The US has not found any cases of variant I mpox, but the US CDC recommended last week that people in the US who have been exposed to mpox or are at high risk of infection should be vaccinated. Gavi, the Vaccine Alliance, has up to $500 million in funding to provide mpox vaccines to countries affected by the outbreak, including the Democratic Republic of Congo and its neighboring countries. A press release detailed that beginning in 2026, Gavi will establish a global mpox vaccine stockpile, similar to its existing stockpiles for cholera, Ebola, meningitis, and yellow fever.

But the WHO emphasizes that vaccines are only part of the response; controlling the spread also requires increased surveillance, diagnostics, and research to fill “gaps in understanding.” The organization has approved an emergency use listing process for mpox vaccines and has developed a regional response plan requiring $15 million, $1.5 million of which is from the WHO’s emergency contingency fund. Tim Nguyen, head of the WHO Health Emergency Program, stated that there are currently 500,000 doses of vaccine in stock, with a potential 2.4 million more doses to be produced by the end of the year. Dr. Abdou Salam Gueye, regional emergency director for Africa, added that the Democratic Republic of Congo and Nigeria will be the first to receive these vaccines.