A man who hadn't had sex in months caught monkeypox after going to a crowded outdoor event. Experts say being intimate is still the most common way the virus spreads.

• A man was diagnosed with monkeypox after attending an outdoor event, according to a report.
• Most people in the current outbreak have caught monkeypox from sexual activity with an infected person.

A man who hadn't had sex for months was diagnosed with monkeypox after attending a crowded outdoor event, in what a researcher described as a "rare" case.

The unnamed man in his twenties from the US developed a rash two weeks after attending a large, crowded outdoor event in the UK, according to a research letter published in the Emerging Infectious Diseases journal on Monday. The rash appeared on his left palm, knuckles on both hands, lip, and torso.

His rash was swabbed and diagnosed as monkeypox. The man didn't have any other typical monkeypox symptoms, the report said. Typical symptoms can include a fever, swollen lymph nodes, and tiredness, as well as lesions on the genitals and anus.

Most monkeypox cases in the current outbreak have been caused by sexual contact

The man's case is unusual because the vast majority of the 39,434 monkeypox cases reported since May outside areas where the disease is endemic have been in gay, bisexual, and other men who have sex with men, who have had intimate, sexual contact, the authors of the report said.

The man identified as bisexual, but told doctors in the ER when he got back to the US that he hadn't had any sexual encounters during his travels or in the preceding three months, according to the report.

Anyone can catch monkeypox including by: rubbing against a monkeypox rash with bare skin, touching contaminated objects, and ingesting respiratory secretions, like saliva, according to the Centers for Disease Control and Prevention.

Experts told Insider the virus is mostly spreading through close contact in the current outbreak — particularly sexual activity, although it is not classed as a sexually transmitted disease.

The longer the amount of time spent with an infected person, the higher the risk of transmission, Dr. Jake Dunning, a senior researcher at the Pandemic Sciences Institute at the University of Oxford, UK, told Insider in an interview before the report was published.

Abraar Karan, an infectious disease researcher at Stanford University and lead author of the report told the San Francisco Chronicle, that the case "should not be a cause for concern in the sense that this remains a very rare event."

"The overwhelming majority of transmission is still through high-risk sexual networks and high-risk sexual exposure," he said.

The risk of catching monkeypox at events is low

In this case, the man attended an event that wasn't primarily attended by men who have sex with men, where he danced close to others wearing "sleeveless tops and shorts" for a "few hours" at a time. He wore pants and a short-sleeved top, the report said. He went to other similar outdoor events over a period of four days.

"Rubbing up against someone partially clothed in a mosh pit over several hours could increase the risk but the risk of an average concert attendee having monkeypox is fairly low at this time," Dr. Peter Chin-Hong, a professor of medicine and an infectious disease specialist at the University of California, San Francisco, told Insider.

The man had also taken two flights and traveled on crowded public trains, according to the report.

Chin-Hong said that surfaces were "not a great way" to catch monkeypox and respiratory spread was "very unlikely with a short transit ride even if monkeypox gets more common in the general population."

Keith Neal, emeritus professor in the epidemiology of infectious diseases at the University of Nottingham, UK, said that airplanes were "even safer" than the metro or buses due to air filtering systems.

The man's symptoms resolved without any treatment 26 days after they started, the report said.