That could be a skewed picture, of course. “MSM have a better relationship with medical practitioners than heterosexual men,” says Lilith Whittles, an infectious disease modeler at Imperial College London, which could mean they are more likely to report monkeypox symptoms and get tested for the virus. “I don't know that we're necessarily looking enough in heterosexual social networks to make the conclusion that this is not a broader problem,” says Boghuma Titanji, a virologist at Emory University who works at a sexual health clinic.

But most researchers say such “ascertainment bias” is unlikely to explain the striking pattern. Although some monkeypox patients have mild infections that may be missed or misdiagnosed, others have very characteristic rashes and agonizing pains that require hospitalization for pain treatment. If many people outside the MSM community had monkeypox, more would have shown up in the statistics by now.

Ashleigh Tuite, an infectious disease epidemiologist at University of Toronto, says she “understands the hesitation” to focus on MSM, given the risk of stigma that could worsen discrimination and cause those who are affected to delay seeking care. “But based on the data that we have, and based on the contact tracing that's been done, it’s very clear that this is an MSM-focused outbreak at this point,“ she says. “Anyone can get monkeypox, but we’re seeing disease activity primarily among” MSM, confirms Demetre Daskalakis, an HIV prevention specialist at the U.S. Centers for Disease Control and Prevention.

Sexual encounters clearly play a role in transmission. Of the 152 people in the UKHSA data set, 82 were invited for additional interviews focusing on their sexual health. Among the 45 who participated, 44% reported more than 10 sexual partners in the previous 3 months, and 44% reported group sex during the incubation period. Exactly how the virus is passed on is less clear. Researchers have found viral DNA, and even infectious virus, in the semen of some patients, but they aren’t sure that is important for transmission; skin-to-skin contact may be enough. (Other sexually transmitted infections, including herpes and scabies, also primarily spread this way.)

https://www.science.org/content/article/monkeypox-outbreak-mostly-affecting-men-sex-men

(http://www.autoadmit.com/thread.php?thread_id=5135629&forum_id=2#44716035)