After acute HIV infection, the majority of patients enter the asymptomatic phase, which can last from 2 to 10 years or more. The length of the asymptomatic phase is related to the number and type of viruses infected, the route of infection, individual differences in the immune status of the body, nutritional conditions and lifestyle habits. This phase is characterized by a continuous slow decrease in the number of CD4+ T lymphocytes. In the late asymptomatic phase, the number of CD4+ T lymphocytes decreases at a faster rate, suggesting that the patient is about to enter the AIDS phase. During the asymptomatic phase, most patients have no obvious clinical symptoms, and some patients may develop persistent enlarged lymph nodes of unknown origin (PGL).