The California Department of Public Health issued a formal health alert on June 16, 2026, warning healthcare providers, laboratories, and local health departments of a significant and accelerating increase in mpox clade I cases in California and the United States — and directly flagging the ongoing World Cup as a factor likely to drive additional imports.
The alert states: "There has been an increase in travel-related introductions of clade I mpox into California and the U.S. in 2026 and clade II mpox cases have increased in California. Increases in clade I community transmission in Western Europe suggest that additional travel-related clade I mpox cases should be expected in California." The full alert is available through the City of Pasadena's Public Health Emergency network, which distributes CDPH clinical bulletins.
