Arizona health officials have confirmed the state’s first infection of an mpox strain responsible for a global outbreak, identifying the case as having been infected while traveling outside the United States.
The Arizona Department of Health and Services said in a statement Wednesday that it has confirmed its first case of Clade I mpox, involving a person with recent international travel.
“ADHS and local public health officials are working to prevent additional infections through monitoring and follow-ups with people who may have been exposed,” the state health agency said.
“There is currently no evidence of local transmission connected to this case.”
Little information about the patient was made public. The ADHS said it was notified of a confirmed travel-associated case of the mpox strain this month.
It is the state’s 34th case of the disease this year, with all but the most recent patient having contracted Clade II mpox.
Mpox is an infection caused by the monkeypox virus, which is spread through physical contact, including direct skin-to-skin contact and sharing of personal items, including bedding, towels and clothing, the ADHS said.
The virus has two main clades: Clade I, which is endemic to Central Africa, and Clade II, which is associated with West Africa.
According to the U.S. Centers for Disease Control and Prevention, Clade I was historically reported to have a much higher case-fatality rate than Clade II, though recent data suggest case-fatality rates for both clades are low, especially when medical care is provided.
Clade II is the cause of the ongoing mpox outbreak that began in 2022, infecting more than 114,000 people worldwide, including about 37,500 people infected in the United States, CDC statistics show. ADHS statistics show Arizona had 582 mpox infections in 2022, followed by 20 in 2023, 66 in 2024 and 17 last year.
Clade I is also responsible for an ongoing mpox outbreak that began in Central Africa in late 2023, and which has since spread internationally, resulting in more than 55,000 confirmed cases, including more than 150 deaths, since January 2024, the CDC said.
The United States reported between 1,700 and 2,800 mpox cases a year from 2023 through 2025, though nearly all have been Clade II.
The CDC said Clade I cases have increased in frequency in the country since March, with more than 20 cases reported in the United States as of June.
