By Caden Pearson
July 22, 2022 Updated: July 22, 2022
The first major peer-reviewed study of monkeypox infections has found that the virus is primarily being transmitted through the sexual activity of gay and bisexual men in the United States and around the world.
The Journal of New England Medicine on Thursday published a study that looked at monkeypox infection across 16 countries between April and June, when cases began to emerge in countries outside of Africa.
The study reported on 528 infections diagnosed between April 27 and June 24, of which 98 percent were in gay or bisexual men with a median age of 38. Of these cases, 95 percent of the infections were suspected to have been transmitted through sexual activity—41 percent also had HIV.
Disease experts and officials from the U.S. Centers for Disease Control and Prevention (CDC) don’t consider monkeypox a sexually transmitted infection but have always said it could be transmitted through intimate contact, such as sex. It can also be spread by close contact and even infected clothing and bedding.
Until this year, monkeypox virus infection in humans has been rare outside of Africa, where it is endemic but mostly spread from animals. But there are now more than 16,000 cases worldwide in countries that mostly have not historically had monkeypox, according to the CDC.
Most of the cases appear to be in North America and Western Europe, where some of the first cases were linked to major LGBT events in Spain and Belgium, considered ground zero for facilitating transmission of the virus.
The leading theory among disease experts is that the monkeypox virus was sexually transmitted at those events.
An uptick in recent U.S. cases suggests transmission occurred at the tail end of Pride Month in late June and early July, based on the study finding that incubation is between three and 20 days (usually seven days).