Trial arms: Arm I: ART initiation according to WHO criteria, at any time during follow-up; Arm II: INH prophylaxis (300 mg/day) for six months and ART initiation according to WHO criteria, at any time during follow-up; Arm III: immediate ART initiation, before reaching the WHO criteria; Arm IV: INH prophylaxis (300 mg/day) for six months and immediate ART initiation, before reaching the WHO criteria.