New 'surprising' case of mpox variant clade lb detected in England
April 7, 2025
The UK Health Security Agency (UKHSA) has confirmed a new clade 1b mpox case in northeast England, notably with no travel history or known connection to previous cases. Diagnosed in March, the patient’s contacts have been traced, and no additional cases have emerged. While UKHSA maintains that the public risk remains low, the unexplained transmission raises concerns about possible undetected community spread. Investigations are ongoing to determine the source of infection. The case underscores the need for continuous mpox surveillance and diagnostic preparedness, particularly as the clade 1b variant has proven more transmissible in other countries.
The UK Health Security Agency (UKHSA) has reported a new clade 1b mpox case in northeast England, marking a notable development in the country’s outbreak response. Unlike previous cases linked to international travel or known contacts, this patient had no recent travel history or connection to previously confirmed infections in the country. The case was diagnosed in March, and a thorough contact tracing effort has been completed with no additional cases identified. UKHSA has stated that the risk to the general public remains low but has launched an investigation into how the individual may have contracted the virus.
This unexplained transmission event raises the possibility of silent community spread of clade 1b mpox, a more transmissible variant that has caused widespread outbreaks in parts of Africa and travel-related infections globally. The clade 1b variant has been detected in several countries outside Africa, including the UK, and has triggered public health alerts from both the World Health Organization and national health agencies. UKHSA’s ongoing vigilance is essential, particularly in light of the new variant's higher human-to-human transmission potential. While the single case does not yet indicate a broader outbreak, its unknown origin demands robust surveillance, expanded diagnostic testing, and public health awareness.
The situation highlights the importance of maintaining international cooperation, rapid detection capabilities, and preparedness for emerging infectious diseases—even in regions where cases have remained sporadic. Public health agencies must remain alert to potential shifts in transmission dynamics and continue investing in early detection and response systems to avoid larger-scale spread. Continued transparency and timely communication from UKHSA will be critical in managing public confidence and ensuring effective containment efforts.