There are four stages of HIV infection:Stage 1: InfectionHIV quickly replicates in the body after infection. Few people develop short term flu.Stage 2: AsymptomaticThis stage of HIV does not cause such symptoms. A person may look perfectly well, but HIV is weakening their immune system. Stage 3: SymptomaticOver time, the immune system gets weakened by HIV and gradually, symptoms develop. Initially, the symptoms can be mild, but they get worse—symptoms like fatigue, weight loss, mouth ulcers and few more. Stage 4: Progression of HIV to AIDSThe ultimate stage, there is no single test for AIDS; doctors will look over several symptoms, including CD4 count.