NEW YORK (AP) — Two Californians diagnosed with mpox may be the first U.S. cases resulting from the local spread of a different version of the virus, health officials said.

The Long Beach Department of Health and Human Services this week confirmed the first case through testing at a state lab. Los Angeles County health officials on Thursday reported a second, similar case.

The risk to the public is low, officials say.

These are not the U.S. first cases of what is known as clade I mpox. But all six previous cases were among international travelers who were believed to have been infected abroad.

Both infected people in California were hospitalized, and they are now recovering at home. Officials declined to give other details. But “at this point in our investigations, we have not identified any association between the two cases,” a Long Beach official said.

Long Beach is located in Los Angeles County but has its own city health department. Investigators there say they have not found a close contact who traveled abroad, nor have they confirmed additional cases. A few of the person’s close contacts have been given a vaccine, said Nora Balanji, the Long Beach department’s communicable disease coordinator.

“We don’t have any proof that there has been ongoing community transmission,” she said. “It’s something we’re looking into. That’s something we’re concerned about.”

Mpox — also known as monkeypox — is a rare disease caused by infection with a virus that is in the same family as the one that causes smallpox. It is endemic in parts of Africa.

Milder symptoms can include fever, chills and body aches. In more serious cases, people can develop lesions on the face, hands, chest and genitals.

One version of the virus — called clade II — was the source of an international health crisis in 2022, when infections escalated in dozens of countries, mostly among men who have sex with men. At one point, the U.S. was averaging close to 500 cases per day.

The infections were rarely fatal, but many people suffered painful skin lesions for weeks. Those outbreaks waned later that year, thanks in part to the Jynneos vaccine made by Bavarian Nordic.

The other version — known as clade I — likewise can spread through sex, but also through other forms of contact. In Africa it has infected a broader range of people, including children.

A newer form of the clade I virus has been widely transmitted in eastern and central Africa. The World Health Organization declared the situation a public health emergency, but last month it said the problem had waned enough that it was no longer an international emergency.

Still, “it’s concerning if this virus has come here and now is starting to be transmitted from person to person,” said Dr. William Schaffner, an infectious diseases expert at Vanderbilt University.

The case report comes amid a federal government shutdown and the layoffs of hundreds of employees at the Atlanta-based Centers for Disease Control and Prevention — the agency that usually would be involved in responding.

Balanji said a few CDC experts have been available to talk to her department about the situation. But Schaffner noted that “the longer the shutdown, the more impaired public health responses are to any outbreaks.”

A U.S. Department of Health and Human Services spokesperson referred questions to local health officials.

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