US public health officials vigilant as newer mpox variant detected | Mpox

A new variant of MPox, a virus formerly known as monkeypox, is now spreading in some communities in the United States and Europe.

The risk to the general population is low, but transmission of the virus in new settings suggests that public health faces greater challenges in identifying cases and stopping the spread.

In October California announced three cases of a new variant known as clade Ib. All three patients – two in Los Angeles and one in Long Beach – were hospitalized and are now recovering.

None of the patients had obvious connections to each other and none had recently traveled abroad, indicating the virus is likely spreading undetected in some communities. Six cases of the new mpox variant have been found among travelers to the US, but this is the first sign of community spread.

The news comes as several European countries – Spain, Italy, the Netherlands and Portugal – are also reporting apparent community transmission of the new variant, while the old variant continues to spread around the world.

In 2025, more than 44,000 cases of mpox were reported. according to to the World Health Organization. This is more than what was recorded in 2024.

Three cases in California may be genomically linked and may be linked to a travel case that occurred in August. according to to the American Hospital Association. The industry group said the information was released by the U.S. Centers for Disease Control and Prevention (CDC) in an advisory Wednesday, although the information does not appear to be publicly available.

The US Department of Health and Human Services had not responded to a Guardian media request at the time of publication about potential genomic links between the cases and whether the virus was spreading in specific networks.

“Given that all three cases in Los Angeles were hospitalized, this gives more confidence that there may be local transmission,” said Miguel Paredes, a genomic epidemiologist at the University of Washington.

Researchers estimate that only one in 33 cases of the old mpox variant are currently detected in Los Angeles. studyco-authored with Paredes, which has not been peer-reviewed or published.

“If you think about a mortality rate of 3% and we're capturing the ones that are 'more serious,' then we're not really capturing the ones that are potentially less serious,” he said.

Vaccination may also complicate the picture.

“Vaccines are good at preventing infection sometimes, but they also create less severe disease, which is good for the person. But it also makes passive surveillance a little more difficult because if you have less severe disease, you're less likely to seek treatment or actually think you have mpox,” Paredes said.

That means researchers and officials need to be more proactive in identifying and tracking cases, rather than simply recording cases of people seeking help, he said. Sampling wastewater would be one relatively inexpensive and discreet way to monitor the spread, he added.

In 2022, cases of the clade IIb mpox variant surged worldwide, infecting nearly 100,000 people worldwide. About a third of the identified cases were in the United States. The vast majority of these cases occurred among men who have sex with men.

However, the new variant, which appears to have emerged in mid-2023 and was first detected in the Democratic Republic of Congo, has not shown the same pattern. It affects men and women, usually between the ages of 25 and 40, with approximately the same frequency.

The outbreak in central and eastern Africa spread through what Jason Kindrachuk calls “dense sexual networks,” or people having multiple sexual partners.

“That's a big part of it,” said Kindrachuk, an international expert on mpox and vice-president of the Public Health Agency of Canada's National Microbiology Laboratory branch.

“Dense sexual networks generally increase the risk of transmission. Regardless of whether you were a man or a woman, you had an increased likelihood or increased risk of infection if you were in these networks.”

But it is difficult to say whether the same pattern will continue in other countries, he said: “Trying to estimate what will happen in other regions of the world when you look at the DRC or Central Africa as a whole is very difficult.”

Internationally, only a few cases of the new variant have been detected among communities, Kindrachuk said, so it is not yet possible to make general statements about the types of networks in which it is spreading.

California has not released information about patients' gender or sexual orientation. But the press release indicated the new variant “primarily affected communities of gay and bisexual men and other men who have sex with men, as well as their social networks.”

People are at higher risk of contracting MPOX if they are gay, bisexual or men who have sex with men, or are transgender or non-binary and have had more than one partner in the past six months. according to at the CDC.

People are also at risk if they have recently visited a sex venue, such as a sex club or bathhouse, or have recently had sex at a large event in a place where mpox is distributed, the CDC notes. MPox It is spread through close skin-to-skin contact, making sexual contact the main mode of transmission.

The Trump administration has rolled back international aid and development work, making such outbreaks much more difficult to monitor and contain. US authorities are focusing on vaccinating people at risk – some of whom may have only received the first of a two-part vaccine.

“I always want to encourage people to get vaccinated,” Paredes said. “It’s like a little thing that can go a long way to protecting you.”

Vaccines are more accessible when they are provided by the government rather than through private insurance, especially among low-income communities, Paredes said. It also helps to offer shots during off hours and in easily accessible locations.

It may be more difficult to use the same methods that worked before to combat MPOX. The US government is largely shut down, and the CDC has lost about a third of its staff this year due to layoffs and resignations.

Many of the public health networks used during the 2022 outbreak (such as STI and HIV monitoring) ended up on the chopping block under the second Trump administration.

Communities affected by mpox can once again take the lead in the fight against this virus.

In 2022, organizations and members of the queer community worked with officials to offer testing and vaccinations, including at gatherings where people might have intimate contact, such as during sex.

“We actually benefited from community organizations coming forward with information, speaking out and trying to reduce that stigma,” Kindrachuk said. He also credited members of affected communities for “enabling people to feel comfortable getting tested and being able to identify risks and potential infections.”