The Right to non-discrimination on grounds of disability (i.e. HIV positive) is explained in these documents:

Legally Obligating Documents
African (Banjul) Charter on Human and People's Rights (3, 18(4))
Convention on the Rights of the Child (2(2))
International Covenant Economic, Social and Cultural Rights (2(2))
International Covenant on Civil and Political Rights (2(1))

Standard Setting Documents
Beijing Platform for Action (99, 108)
Cairo Programme of Action (8.29, 8.34)
Universal Declaration of Human Rights (1, 2, 6)