Promiscuity does not propagate sexually transmitted diseases. You are working off of a false stereotype which has limited the capacity of your rational thought, and as a result, you imagine a world which does not exist, and propose solutions which will not work. This is a common problem with HN people. They come up with this one idea that kind-of makes sense, and then stop thinking, and shape their whole thought process around this false premise.

Did you take a second to google this idea you had to see if it made sense? No; because if you had, you'd have found that HIV is spread by blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, breast milk. People who inject hormones, silicone, steroids, and drugs, can get or transmit HIV by sharing needles, syringes, or other injection equipment. It can be spread through pregnancy or stepping on an infected needle at the beach. It's often spread by not using protection during sex. And straight and gay people both get it.

Gay people do not have more sex partners than straight people. Promiscuous people do have more partners than non-promiscuous people. Gay, straight, bi, queer, etc, can all be promiscuous, just like they can all also be monogamous or even asexual. You may not like that de-simplification, but it exposes the flaw in this notion that gay people are sluts and sluts get STDs. It just doesn't work that way. Safe sex, even if you fuck a lot of people, makes you much less likely to get an STD than if you only occasionally had sex and never use protection. In countries with limited access to safe sex, all people across all demographics contract it. It's not just poor Africans and gay men, despite that being the unfortunately common misconception.