The clade I mpox situation has entered a new and more concerning phase as of June 2026. The Centers for Disease Control and Prevention confirmed that more than 20 clade I cases have been detected in the United States, all diagnosed in individuals with recent travel to regions with active clade I outbreaks or exposure to people with such travel histories. But the more significant development — the one that changes the risk calculus — is a statement buried in the same CDC update: beginning in Fall 2025, several European countries began reporting locally acquired clade Ib cases among men who have sex with men who had no documented travel to Central or Eastern Africa. The CDC states explicitly: "We expect additional cases in Europe and the United States."
This is not a theoretical escalation. It is a documented epidemiological shift, confirmed by the European Centre for Disease Prevention and Control, which noted in its May 2026 surveillance report that from April 2025 to March 2026, 336 clade I mpox cases were confirmed across 15 European countries. Some of those cases reflect local community transmission that has taken root independent of African source countries — exactly the scenario that global health officials feared when the WHO declared clade I mpox a Public Health Emergency of International Concern in August 2024.
