Livestock bacterial disease spreading among humans in Europe

In Barcelona, researchers found further evidence that the bacterium was spreading between people.

Nine cases identified between December 2025 and March 2026 were caused by strains that differed by just zero to four genetic mutations, suggesting the infections were part of a recent transmission chain rather than separate cases acquired from animals.

The bacterium can survive in crusted areas on the skin for up to 42 months, according to Dr McHale, raising questions about the role of contaminated surfaces, equipment and shared spaces.

People should not be alarmed by the infection, which is treatable with a course of antibiotics, he added. 

This could make hygiene particularly important in places such as saunas, where people may have prolonged skin contact with others and with shared surfaces.

Saunas have historically been a destination for gay and bisexual men seeking social and sexual contact.

Dating apps such as Grindr have since made casual encounters in these environments far easier to arrange, experts say. 

“What we’re seeing is the kind of in-person venues like saunas being combined with apps,” said Rusi Jaspal, a Professor of Psychology at the University of Brighton and expert on wellbeing among gay men. 

“Someone might, for example, be in a sauna but also have their app on, and that might be a way of getting people to come to the sauna. So they’re not only attracting people who are already in the sauna, but who might be outside of that environment and coming in.”

Progress and complacency

Professor Jaspal believes the success of Pre-Exposure Prophylaxis (PrEP), which protects against HIV, has also played a role. 

“I think that is a really big contributor,” he said. “On the one hand, obviously it’s fantastic that PrEP is there. It prevents HIV; it’s extremely effective against HIV. But it’s not effective against other infections.”

He argued that because PrEP has removed the fear of HIV that shaped gay men’s sexual behaviour for decades, some men are now having condomless sex with more partners, in the belief that other infections are treatable in a way HIV once was not.

“Because they think, well, everything else is treatable – gonorrhoea, syphilis, it’s all treatable – they’re going to just not use condoms,” he said. “That is not only creating more of a risk of infection, but I think people are having more partners as well.”

Sexual contact is not the only route by which the bacterium appears to be spreading.

In Norway, ten cases have been linked to martial arts, with some infections occurring during training in Norway and others during trips to Thailand. 

One case report described a 34-year-old Muay Thai fighter who developed recurrent pustular lesions after returning from a training trip, later confirmed as D. congolensis through whole-genome sequencing.

Dr McHale said the bacterium tends to take hold where the skin has already been compromised in some way.

“Predisposing factors for infection include cutaneous microtrauma, for example, from ultraviolet radiation, tick exposure and insect bites, and maceration of the skin,” he said.

Dermatophilus congolensis is notoriously difficult to grow in culture, meaning infections can easily go undiagnosed or be mistaken for more common skin conditions.

Researchers in Barcelona have warned that cases could be going unrecognised because sexual health clinics do not routinely test for the bacterium.

But Professor Jaspal believes the legacy of the HIV/Aids epidemic explains why this cluster was identified so quickly.

He said the crisis of the 1980s, when confusion and stigma allowed the virus to spread largely undetected, forced public health bodies to build far stronger surveillance and communication systems for outbreaks among gay and bisexual men. 

That same infrastructure, he argued, has since been used to manage subsequent threats such as mpox – and now this obscure bacterium – far more effectively.

“I think we are quite rightly identifying cases early on, so that we can then communicate that risk to people and encourage precautions to protect themselves,” Professor Jaspal said. “That is really, really important.”

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