Mpox Cases Confirmed in California Linked to International Travel

California well being officers have confirmed the primary identified U.S. case of the extra extreme clade I pressure of mpox in a Riverside County resident who lately traveled to the Middle East. The particular person has totally recovered and is not contagious, in keeping with Riverside County Public Health.

This case follows a separate affirmation by the California Department of Public Health (CDPH) of one other clade I mpox an infection in San Mateo County, linked to journey to Africa. While each instances are related to worldwide outbreaks, officers emphasize that the danger to most people stays “very low” and there is no evidence of ongoing transmission of clade I mpox within California or the broader U.S.

Here’s what to know about Mpox and its prevalence in California.

What Is Mpox and Why Clade I Matters

Mpox, formerly known as monkeypox, is a zoonotic viral disease that spreads through close contact with infected individuals or animals. Two virus types cause it: clade I and clade II. Clade I, the strain involved in both recent California cases, has historically been associated with more severe illness and higher mortality rates, though recent outbreaks have shown milder symptoms.

Symptoms of mpox include fever, rash, swollen lymph nodes, and fatigue, typically appearing three to 21 days after exposure. The virus can be transmitted through skin-to-skin contact, respiratory droplets, and contaminated objects. While not classified as a sexually transmitted infection, mpox has disproportionately affected men who have sex with men.

Local and statewide California response to mpox

Riverside County has reported nine mpox cases in 2025, a sharp decline from the 316 cases seen in 2022. The recent clade I case is the first in the county this year. In contrast, Northern California has seen a slight uptick in clade II cases, averaging 13 per week in August, according to CDPH.

“Travel is often a time of connection, exploration and community,” mentioned Riverside County Public Health Officer Dr. Jennifer Chevinsky. “If you may engage in intimate contact while traveling, getting vaccinated against mpox is a simple and effective way to protect yourself and others.”

How does mpox spread?

Mpox is usually passed from rodents and primates to humans through bites, aerosol transmission, or contact with infected fluids.

Person-to-person transmission is usually through close contact with respiratory secretions, inflected skin lesions or recently contaminated objects, according to the WHO.

The California Department of Public Health said the clade I strain of mpox “spreads similarly as clade II mpox, through close (skin-skin), intimate and sexual contact.”

Updated mpox vaccination guidance

CDPH has updated its vaccination recommendations regarding the emerging clade I cases. The Jynneos vaccine, administered in two doses one month apart, is effective against both clade I and clade II strains. Health officials recommend receiving the first dose at least six weeks before travel to outbreak regions, with the second dose given two weeks before departure.

Those already receiving both doses are not advised to get additional shots.

Mpox prevention and public health messaging

To reduce the risk of transmission, CDPH advises:

• Getting vaccinated if at risk.
• Avoiding intimate contact for 21 days if exposed.
• Isolating and notifying contacts if infected.
• Practicing good hygiene and avoiding shared items with infected individuals.

Who is the risk of contracting mpox in the United States?

The CDC reports a low risk of getting pox in the general population. However, the risk to gay, bisexual, and other men who have sex with men who have more than one sexual partner is assessed as low to moderate in the United States.