LONDON (AP) — British health officials said they cannot tell if the spread of monkeypox has peaked in the country as they announced another 45 cases Friday, bringing the total in the disease’s biggest-ever outbreak beyond Africa to 366 cases.

Britain’s Health Security Agency said 99% of the total cases were in men and that nearly all of the 152 men who provided detailed information identified as gay, bisexual or men who have sex with men. About 80% of cases were in London, and the median age of the people infected was 38, the agency said.

“We cannot yet determine if transmission has stopped increasing,” the agency said in a report, citing the reporting delay between when patients experienced symptoms and were confirmed as having monkeypox.

Anyone, regardless of their sexual orientation, is susceptible to the monkeypox virus if they come into close physical contact with an infected person or their bedsheets or clothes.

“Findings show that monkeypox is being distributed in geographically diffuse sexual networks,” the British scientists wrote, adding that some of these connections extended beyond the U.K. “Most cases reported having sexual contact with new or casual partners, sometimes in the context of cruising grounds or chemsex,” the experts said, referring to sex combined with drug use.

The experts noted that contact details for sexual partners were often unavailable.

Last month, a leading adviser to the World Health Organization said the outbreak in Europe and beyond was likely spread by sex at two recent raves in Spain and Belgium.

Earlier this week, WHO said more than 1,000 cases of monkeypox had been reported in 29 countries that haven’t previously had outbreaks of the smallpox-related disease, including the United States, Portugal, Spain, Italy and Canada. Poland reported its first case on Friday. No deaths have been reported.

Britain’s Health Security Agency found that many of the cases in the U.K. involved men who reported having sex in saunas, dark rooms or sex clubs.

“Therefore, collaborating with sex-on-premises venues to implement targeted interventions would support outbreak control,” the agency said. It added that using targeted messages on dating apps might also be useful or “support innovative approaches to contact tracing.”

WHO chief Tedros Adhanom Ghebreyesus said it was likely monkeypox has been transmitting undetected for some time beyond Africa and that the U.N. health agency was concerned the disease might start to infect more vulnerable groups, such as pregnant women and children.

WHO’s top monkeypox expert, Dr. Rosamund Lewis, said earlier this week there was still “a window of opportunity” to stop monkeypox from jumping into the general population and those more at risk of severe disease.

Most monkeypox patients experience only fever, body aches, chills and fatigue. People with more serious illness may develop a rash and lesions on the face and hands that can spread to other parts of the body. In severe cases involving people without access to health care, WHO has noted a death rate of 3 to 6%.

The ongoing outbreak of monkeypox in Britain and elsewhere, marks the first time the disease has been known to spread among people who have no previous travel links to Africa.

The Africa Centers for Disease Control and Prevention says that so far this year, there have been more than 1,400 monkeypox cases and 66 deaths in four countries where the disease is endemic — Cameroon, Central African Republic, Congo and Nigeria. Genetic sequencing of the virus hasn’t yet shown any direct link to the outbreak outside Africa.

British scientists said they found three mutations in the monkeypox virus spreading in the U.K. that they classed as “high priority” since they were found to worsen the disease in rats. They said more research was needed to tell if the changes were significant.

Copyright © The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.