▁Democratic ▁Republic ▁of ▁the ▁Congo . ▁H IV ▁found ▁in ▁t issue ▁samples ▁from ▁a ▁ 1 5 - year - old ▁African - American ▁te en ager ▁who ▁died ▁in ▁St . ▁Louis ▁in ▁ 1 9 6 9 . ▁H IV ▁found ▁in ▁t issue ▁samples ▁from ▁a ▁Norwegian ▁sail or ▁who ▁died ▁around ▁ 1 9 7 6 . ▁ ▁Two ▁species ▁of ▁H IV ▁inf ect ▁humans : ▁H IV - 1 ▁and ▁H IV - 2 . ▁H IV - 1 ▁is ▁more ▁vir ul ent ▁and ▁more ▁easily ▁transm itted . ▁H IV - 1 ▁is ▁the ▁source ▁of ▁the ▁majority ▁of ▁H IV ▁in fe ctions ▁throughout ▁the ▁world , ▁while ▁H IV - 2 ▁is ▁not ▁as ▁easily ▁transm itted ▁and ▁is ▁largely ▁conf ined ▁to ▁West ▁Africa . ▁Both ▁H IV - 1 ▁and ▁H IV - 2 ▁are ▁of ▁prim ate ▁origin . ▁The ▁origin ▁of ▁H IV - 1 ▁is ▁the ▁central ▁common ▁ch imp anze e ▁( Pan ▁tro gl ody tes ▁tro gl ody tes ) ▁found ▁in ▁southern ▁Cam ero on . ▁It ▁is ▁established ▁that ▁H IV - 2 ▁origin ated ▁from ▁the ▁so oty ▁mang ab ey ▁( C er co ce bus ▁at ys ), ▁an ▁Old ▁World ▁mon key ▁of ▁Guinea ▁B iss au , ▁Gab on , ▁and ▁Cam ero on . ▁ ▁It ▁is ▁hypoth es ized ▁that ▁H IV ▁probably ▁transferred ▁to ▁humans ▁as ▁a ▁result ▁of ▁direct ▁contact ▁with ▁prim ates