Epidemiology and Characteristics of MPXV Clade I cases in the WHO European Region, 2024-2025

Abstract BACKGROUND A public health emergency of international concern (PHEIC) was declared in August 2024 following a sharp increase in mpox cases linked to the emergence of monkeypox virus (MPXV) clade Ib. AIM To characterise imported and locally acquired mpox clade I cases reported in the WHO European Region since August 2024, and to assess transmission patterns and response measures. METHODS Between 14 August 2024 and 23 November 2025, we collected key information on MPXV clade I infections reported by member states of the WHO European Region through the International Health Regulations. We contacted reporting countries to collect age, sex, travel history, most likely route of transmission, clinical course, contacts and type of exposure, and implemented control and prevention measures. RESULTS Eighty-two cases of MPXV clade I infection were reported; forty-five were imported and 37 were infections acquired in reporting member states. Seventy-nine were typed as clade Ib and two as clade Ia. Most imported cases reported heterosexual or close physical contact as possible exposure. Secondary transmission occurred in six households. One healthcare worker was infected. Since October 2025, 17 autochthonous cases in men were most likely infected through sex with other men. CONCLUSIONS Imported cases of MPXV clade I infection were associated with limited household transmission. The increase in autochthonous infections among men with recent sexual contact with other men suggests undetected spread in Europe, that may become sustained. Continued surveillance, case and contact investigation are needed to understand MPXV clade I epidemiology and drivers of MPXV clade I transmission in Europe.