A new strain of mpox, known as the clade Ib subtype, has been confirmed in Switzerland, marking the country’s first case of this more dangerous variant. The strain, which emerged in the Democratic Republic of the Congo (DRC) in 2023, is now spreading beyond Africa. European countries, including Switzerland, the United Kingdom, Germany, Belgium, France, and Sweden, have all reported infections, raising concerns about the strain’s ability to spread globally. Health authorities continue to monitor the situation, but they maintain that the risk to the public remains low.
What Is Mpox Clade Ib?
Mpox, a viral disease caused by the monkeypox virus, has been a growing concern worldwide. The clade Ib subtype, a more dangerous version of the virus, was first detected in the DRC in 2023. Since then, it has spread across Central Africa, with significant outbreaks in countries like Burundi and Uganda. Clade Ib has been found to spread more easily and poses a greater risk to children, making it a more alarming strain for health officials.
Recent Confirmations of Mpox Clade Ib in Europe
Health authorities in several European countries have confirmed cases of the clade Ib strain in travelers returning from Africa. In Switzerland, the first case was reported in April 2025. The individual had recently returned from Uganda and was immediately isolated. There was no immediate risk to the public. Similarly, other European countries have reported cases linked to travel, though some local transmission has been observed.
Switzerland Reports First Case
Switzerland confirmed its first mpox clade Ib case in April 2025. The patient had traveled to Uganda, a country in Central Africa, where the strain is currently widespread. Health officials acted quickly, isolating the patient to prevent further transmission. Authorities reassured the public that there was no significant risk of a wider outbreak.
The United Kingdom and Germany’s Cases
The United Kingdom has reported 11 cases of mpox clade Ib, with most infections linked to travel to Africa. However, a case in April 2025 involved a patient who had not traveled recently, suggesting that local transmission could occur. The UK government has taken steps to control the outbreak by securing over 150,000 doses of the vaccine and opening vaccination centers across the country.
Germany has confirmed eight cases of mpox clade Ib, with the first infection detected in October 2024. A cluster of five additional cases was reported in December, including infections among family members. Health officials have assured the public that no widespread transmission has occurred.
Belgium and France Report Cases
Belgium identified five cases of the new mpox strain between December 2024 and February 2025. The cases included both travelers and one child. Authorities monitored the situation but did not find evidence of widespread risk.
In France, two cases of clade Ib were confirmed, both of which were linked to travel in Central Africa. One case involved a person in Brittany who had close contact with travelers from the outbreak region.
Sweden’s Early Detection Outside Africa
Sweden became the first country outside Africa to detect the clade Ib strain in August 2024. The patient had contracted the virus while visiting an African region affected by the outbreak. Since then, Sweden has been closely monitoring the situation to prevent further spread.
Global Spread of Mpox Clade Ib
Beyond Europe, mpox clade Ib has been reported in several countries outside Africa, including the United States, Canada, Brazil, China, India, Thailand, Oman, Pakistan, Qatar, and the United Arab Emirates. While the strain is spreading globally, health authorities continue to emphasize that the overall risk remains low, especially in Europe.
What We Know About the Spread and Risks
Mpox primarily spreads through close skin-to-skin contact. The virus causes symptoms like fever, rash, headache, and swollen lymph nodes. Health officials advise caution, especially among travelers returning from areas where the outbreak is ongoing.
Authorities Urge Continued Vigilance
Despite the growing number of cases, the risk to the public in Europe remains low. Health agencies continue to monitor the situation closely and encourage people to stay alert, particularly those traveling to outbreak regions. Vaccines and antiviral treatments are available and play a crucial role in preventing further spread of the disease.