Symptoms usually appear around 2-6 weeks after HIV infection, and about 50%-70% of infected patients may develop HIV viremia and acute damage to the immune system, mainly manifesting as fever, malaise, sore throat and general malaise, similar to upper respiratory tract infection, with a few patients having headache, skin lesions, meningeal inflammation and acute polyneuritis. On physical examination, swollen lymph nodes in the neck, occipital area, axillae and enlarged liver and spleen can be seen, and the above symptoms disappear within 1-2 months. Laboratory tests show a significant decrease in total lymphocytes, increased sedimentation, negative alloantibody tests, elevated transaminases and alkaline phosphatases, and a significant decrease in CD4-positive T lymphocytes after several weeks due to HIV invasion of CD4-positive T cells.