There is a seg. unit in Texas where almost all are HIV positive from what I am told. Most prisons have seg. units to house those who are homosexual or bi sexual.
This is suppose to be for their protection, but, instead it has the opposite effect of helping spread HIV, Hepatitis, and TB. Some straight men find their way into those units as well by pretending to need protection. They have sex with pre-op transexuals and others who are housed there.