Experts at the XVII International AIDS Conference in Mexico City say that discrimination aimed at gay men around the world must be stopped and that countries should put more programs in place to prevent HIV transmission among gay men, Bloomberg reports.

“In many countries homosexual activity is against the law,” says UNAIDS executive director Peter Piot. “It is underground and impossible to organize these programs.”

According to the article, more than a quarter of gay men in Africa and the Caribbean are living with the virus, but widespread stigma and criminalization have hindered many of these countries—including Jamaica, Kenya and Ghana—from emphasizing this group in their HIV prevention efforts.