California officials confirm first 3 unrelated US cases of severe mpox strain with no travel history

LONG BEACH, Calif. -- The California Department of Public Health and local health officials in Long Beach and Los Angeles County have identified three unrelated cases of clade I mpox in Californians who did not report recent travel outside the United States.

Prior cases of clade I mpox in the United States have been associated with international travel to areas where clade I mpox is circulating.

All three cases required hospitalization and the patients are now recovering.

Local health departments and CDPH are conducting enhanced surveillance and contact tracing to identify any additional cases and prevent further transmission. At this time, the risk to the general public remains low.

"As we continue to monitor the situation, it is crucial for Californians to stay informed and take preventive measures, especially persons who are more likely to be exposed to mpox," said Dr. Rita Nguyen, Assistant State Public Health Officer.

"Clade I mpox cases can be severe. Risk of severe disease and hospitalization are highest for people with weakened immune systems, so it's critical to protect yourself by getting both doses of the mpox vaccine if you or your sex partner(s) may be at risk for mpox."

The first U.S. case of a more severe strain of mpox without any recent travel history has been identified in California earlier this week.

Health officials said this week that the case was confirmed in a Long Beach resident. The patient required hospitalization and is now isolating and recovering at home.

No other identifying details were provided about the patient, including name, age or sex.

There are two types of the virus that cause mpox: clade I and clade II, with clade roughly meaning they are descended from a common ancestor organism. Clade I has historically been associated with severe illness and death, and is endemic to parts of central and western Africa, according to the CDC.

Clade II was responsible for a large outbreak that peaked in summer 2022, leading to more than 100,000 cases in 122 countries, including more than 30,000 cases in the U.S.

The less severe strain in the U.S. has continued circulating at low levels and has remained relatively stable.

Parts of Africa have been dealing with sustained person-to-person spread of the more severe strain of mpox. All six previously confirmed cases of the more severe strain in the U.S. have been among people who had recently traveled to areas associated with the outbreak in central and eastern Africa, according to the CDC.

In November 2024, California reported the first domestic case of the more severe strain in a traveler from Africa who experienced mild illness.

People with mpox, which was formerly known as monkeypox, often get a rash that can be located on hands, feet, chest, face, mouth or near the genitals, the CDC said.

Most people with mpox typically recover within two to four weeks without specific treatments.

Currently, the JYNNEOS vaccine, a two-dose vaccine approved by the Food and Drug Administration to prevent smallpox and mpox, is the only vaccine being used in the U.S.

The JYNNEOS vaccine is recommended for adults at high risk for mpox, which includes people who are gay, bisexual or other men who have sex with men and have recent or upcoming risk factors like multiple sexual partners, intimate contact with someone who may have mpox, or sex at commercial venues.

About Mpox

Mpox is an infection caused by the monkeypox virus. There are two types of mpox, clade I and clade II. Both types cause similar symptoms and can be prevented using the same methods and vaccine. Mpox mainly spreads through close contact to a person who has mpox infection. This includes:

• Intimate physical contact such as massages, cuddling, or sex (oral, anal, or vaginal)


• Direct skin-to-skin contact with the rash, scabs, or body fluids that touched sores


• Sharing a living space or personal items with someone who has mpox


• Spread from a pregnant person with mpox to the fetus or baby

Casual contact, like one might have in an airplane, office, or store, is unlikely to spread mpox.

ABC News' Mary Kekatos contributed to this report.