| Three people in California who had not recently traveled overseas have been diagnosed with a particularly infectious and severe variant of mpox, health officials said last week, the first such cases in the US identified since 2022. The new cases of mpox– formerly monkeypox – among unrelated Southern California residents raise concerns about community spread in the US. Prior infections with this strain, called clade I, were connected to international travel. Mpox is a disease caused by a virus in the same family as smallpox, according to the US Centers for Disease Control and Prevention. Symptoms include a distinctive rash that appears 3-17 days after infection and goes through several stages before healing, the CDC says. Other symptoms include chills, a fever or swollen lymph nodes. “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,” Rita Nguyen, California’s assistant state public health officer, said in a statement. Officials say the spread is primarily impacting gay and bisexual communities and their social networks. The person-to-person spread of this strain is a new and worrying development for the US. Mpox has two variants: clade I and clade II. In 2022 during the global mpox outbreak, clade II was the dominant strain. Endemic to West Africa, that version is less severe and the rash doesn’t always appear across the entire body. That variant is mostly spread through sexual contact and has primarily infected men who have sex with other men.
Clade I is more severe and more easily spread, leaving more people vulnerable. It’s usually acquired through exposure to animals that carry the disease, household contact or close sexual contact. It’s deadlier and more likely to be found in children than the other strain. The clade I outbreak originated in Central Africa, and the area has confirmed more than 40,000 infections and 100 deaths since 2024. The US has recorded six travel-related cases this year. Tracking both community spread and the nationwide picture could prove difficult this year. The CDC uses wastewater testing in the US to follow the disease and the agency has a team in Africa helping with the global response. But during the government shutdown, the CDC is operating with a skeleton staff and isn’t reporting new wastewater data. California officials said they are coordinating with the CDC despite the shutdown. All three of the California patients were hospitalized and are recovering. The CDC recommends two doses of the mpox vaccine for anyone at high risk of infection specifically people who are gay, bisexual, transgender, have HIV or know they have been exposed to the virus, California officials said. The CDC has issued travel health notices for clade II in Liberia and Sierra Leone, warning of possible exposure and recommending vaccination.
If you believe you've been exposed, health officials advise talking to a health care provider and finding a vaccine before symptoms develop. – Jessica Nix | 
