I think AidsAids would have behaved more or less exactly like syphillis did.
In english: firstThe first stage of syphilis you often don't recognize as syphilis at all /or ignore because the few ugly things on your skin dissapear afterdisappear 4-6 weeks after infection.
theThe stage when you get ugly follows after 8-9 weeks after infection. aA few months aferafter you got ugly, you get beautiful again. and aA few months later, you get ugly again. (and this repeats)
maybe syphilis stopsSyphilis may stop totally (or for just some months or years) at that stage, so you don't feel and look sick anymore but you are still infectious.
So, like in the aids case, you have some people who look healthy aldoughalthough they are infected and spread the disease for years. (yes, syphilis makes more of its victims peramnentlypermanently ugly in shorter time, but therefore it's more infectious (it can even be transmitted through food) (just think about medieval taverns)
so I think aldoughalthough there are that differences
- faster in making you ugly (in average) (aldoughalthough you can stay beautiful for years and infect your whole town)
- much more infectious
- slower in making you ugly (in average) (aldoughalthough you can get ugly and die from HIV quickly, too + it's not as slow as you think when unthreateduntreated-see [hiv behaviour[HIV behavior when unthreated][1]untreated][1] -> > 90% die after 2-15 years, ~ 80% die after 5 years and 10 years.)
- much less infectious
theThe effects on a medieval world would be more or less the same. (I think the differences compensate themselves)
sinceSince syphilis stayed in europe until the first world war, (history lessons) I think syphilis was worse than the black death epidemic you're talking about (70.000.000-200.000.000 deaths). (caused more deaths since it had much more time) ( ? )
=> Aids would be worse than the black death epidemic you're talking about as well. ( ? )
(If anyone argues that aids would kill you faster in a medieval world because you get an immune deficit, thatsthat's true, but syphilis would kill you faster as well if you get additional diseases ( ? ). [1]: https://www.dailystrength.org/group/hiv/discussion/how-long-does-it-take-when-untreated