Or maybe black people are just more retarded on average, and therefore get themselves infected by avoidable diseases at a much higher rate than any other group.
Look at the Asians here, for example. They are extremely under-represented, considering that the epicenter locations have a much higher Asian % than the national average. Asians are 33% or so in San Francisco itself, for example. 15.9% in California, 10.8% in New York State. And the black population there is lower than the national average, about 6% in both San Francisco and California. So they are extremely over-represented. Hispanics are only over-represented by about double (by San Francisco demographics), which is enormously less than the rate of over-representation of blacks. Meanwhile whites are only slightly under-represented, probably breaking even in reality. So maybe it's more about the spectrum of being retarded/not retarded than any specific cultural attitudes.
If an Asian person hears about a new terrible STD, they will stop and go "hmm. I like sex, and I really want to go. But rationally I know it's not worth the risk."
They have the ability to make a painful choice that goes against their impulses (this is also why you almost never hear about Asian people "snapping" and committing extremely violent, impulsive, unplanned crimes that they instantly get caught for). And if they do decide to interact with the mlm world still, that same control over their impulses will make them stop and insist on condoms, forego ass eating just for the moment, curate strangers before sex, take notice of boils, etc.
A gay white person would do those things half the time, and be an impulsive retard the other half. A gay Basketball American would be impulsive and retarded 99% of the time. Or at least, that's my theory. It lines up with why every other graph ever made also looks like this, with Asians having the best result in whatever is being measured.