Switzerland confirms clade 1b mpox as Hong Kong issues warning
April 9, 2025
Switzerland has reported its first case of clade 1b mpox in a traveler returning from Africa, marking another addition to the list of countries detecting this more virulent strain. The patient is in isolation, and Swiss health officials confirm there is no risk of further transmission. Clade 1b is driving the current outbreak in central Africa, particularly in the Democratic Republic of the Congo. Meanwhile, the UK recently reported a clade 1b case with no travel history, prompting Hong Kong officials to issue public advisories. Clade 1b has now been detected in at least 15 countries across three continents.
Switzerland has confirmed its first case of clade 1b mpox in a traveler returning from Africa, adding to growing international concern about the spread of this more virulent strain. The Swiss Federal Office of Public Health reported that the patient is currently in isolation and poses no infection risk to the public. This detection aligns with a wider pattern of imported cases of clade 1b across Asia, Europe, and North America, most of which are linked to travel in or around outbreak zones in central Africa.
Clade 1b has emerged as the dominant driver of the mpox outbreak in central Africa, with the Democratic Republic of the Congo at the epicenter. Unlike clade 2—which caused the 2022 global outbreak primarily among men who have sex with men—clade 1b is considered more transmissible and virulent, affecting broader segments of the population, including children and healthcare workers.
This week, alarm bells rang in the United Kingdom when a clade 1b case was detected in an individual with no recent travel history or known links to other infected persons, signaling potential undetected community transmission. In response, Hong Kong authorities urged residents to remain vigilant. While Hong Kong has not yet reported any clade 1b cases, it has recorded 72 mpox cases overall since 2022, including four so far in 2025.
The expanding geographic spread of clade 1b, alongside isolated cases with unknown origins, highlights the need for continued global surveillance, rapid testing, and public health readiness. With clade 1b already present in at least 15 countries, health officials worldwide must stay alert, reinforce outbreak preparedness, and collaborate internationally to prevent wider community transmission. Early containment remains critical in curbing the spread of this evolving threat.