Former HIV researcher here. Right now, HIV is a manageable condition, but ONLY because of the availability of drugs which suppress the virus. The virus eventua

Former HIV researcher here. Right now, HIV is a manageable condition, but ONLY because of the availability of drugs which suppress the virus. The virus eventually learns how to get around the drugs, at which point the patient either switches drugs or dies in a few years. Without drugs, HIV is (near) 100% fatal. And since it takes a few years to kill, infected people have plenty of time to pass it on. Which they do. Also, the first HIV infection feels like a minor cold. Most people would not even know they were HIV positive (until their immune system collapsed), were it not for lab testing. Then just apply some basic epidemiology to these facts, and you see that you have a disease which has the potential to infect (and thus kill) a sizeable percent of the population. As in double-digit percentages.