I've got the cure for AIDs. It's so powerful it even cures Herpes. In fact, it'll cure most every STD. It's more effective than any other drug or device made. The cure is free, and is immediately available worldwide. What's the name of this super-cure?
Now, given it's not 100 percent effective. There are rare cases of disease transmission due to things such as accidental blood transfusion. And in cases of illicit drug use, transmission is possible via dirty needles (of course a different sort of abstinence cures this as well). But over time, these diseases could be effectively eradicated amongst populations that practice abstinence and chastity.
We've got all sorts of foundations, drug companies, and government programs that claim to be looking for a cure when the best cure has been around for millenia. It's up to you to use it.