What is the preclinical phase of HIV?

Answer 1

Human Immunodeficiency Virus, better known as HIV, is a retrovirus that leads to Acquired Immunodeficiency Syndrome, or AIDS. HIV is a retrovirus, meaning the virus inserts a copy of its RNA genome into the host genome through reverse transcription, changing the host cell's genome. HIV has three stages of infection; acute infection, followed by clinical latency, leading to AIDS. When HIV is contracted, the host will show signs of acute infection within the first 28 days with signs and symptoms that include fever, headache, fatigue, pharyngitis, GI symptoms, lymphadenopathy, arthralgias, and myalgia. Oftentimes, hosts will be unaware that they are infectious after the initial acute infection due to the "flu-like" symptom presentation. The acute infection will dissipate after a few weeks, and the host will become asymptomatic. However, the virus will remain latent within the CD4 and macrophage white blood cells. In the early stages of HIV, the host may feel normal and healthy. Antibody development for HIV takes anywhere from 2 weeks to 6 months, so antibodies will not be detected, but virus particles can be found in the bloodstream. This is particularly dangerous, since the host may associate “asymptomatic” with not being infectious, and end up transmitting the disease to others. The normal range of CD4 cells is 800 to 1,200 cells/mm³. During the latent stage of the HIV infection, also known as chronic HIV infection, HIV levels gradually increase and the number of CD4 cells decreases. Chronic HIV infection can last from 6 months to 10 years, depending on the infected host. As the HIV virus replicates, CD4 cell levels decline, indicating increasing damage to the immune system. The immune system becomes significantly compromised when CD4 levels drop below 500 cells/mm³. When a host's CD4 count is below 200 cells/mm³, and a host has an opportunistic infection (i.e. pneumonia, Salmonella infection, candidiasis, toxoplasmosis, TB), the patient enters the last stage of HIV, which is the diagnosis of acquired immunodeficiency syndrome (AIDS). According to the Centers for Disease Control and Prevention (CDC), to be diagnosed with AIDS, a person with HIV must have a CD4 count less than 200 cells/mm³