Final answer:
The initial stage before the appearance of HIV-specific antibodies in the blood lasts for 3 weeks. During this stage, patients may experience flu-like symptoms and are highly contagious. After this stage, patients enter a period of clinical latency.
Step-by-step explanation:
The initial stage before the appearance of HIV-specific antibodies in the blood lasts for 3 weeks.
During this stage, known as acute HIV infection, patients may experience a flu-like illness that can last for a few weeks. They have a large amount of virus in their blood and are highly contagious. To confirm acute infection, a fourth-generation antibody-antigen test or a nucleic acid test (NAT) must be performed.
After the initial stage, patients enter a period of clinical latency, which can last for several decades if they receive antiretroviral therapy. Near the end of this stage, viral load increases and CD4 T-cell count decreases, leading to the development of symptoms and increased susceptibility to opportunistic infections.