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HIV Infection Cycle
HIV disease has a well-documented progression. Untreated, HIV is almost universally fatal because it eventually overwhelms the immune system—resulting in acquired immunodeficiency syndrome (AIDS). HIV treatment helps people at all stages of the disease, and treatment can slow or prevent progression from one stage to the next.
A person can transmit HIV to others during any of these stages:
Window Period -Acute infection: Within 2 to 4 weeks after infection with HIV, a person may feel sick with flu-like symptoms. The time period after contracting the infection and until the body has developed enough antibodies for an accurate positive test result. This is called acute retroviral syndrome (ARS) or primary HIV infection, and it's the body's natural response to the HIV infection. (Not everyone develops ARS, however—and some people may have no symptoms.)
During this period of infection, large amounts of HIV are being produced in the body. The virus uses important immune system cells called CD4 cells to make copies of itself and destroys these cells in the process. Because of this, the CD4 count can fall quickly.
The ability to spread HIV is highest during this stage because the amount of virus in the blood is very high.
Eventually, the immune response will begin to bring the amount of virus in the body back down to a stable level. At this point, the CD4 count will then begin to increase, but it may not return to pre-infection levels.
Clinical latency (inactivity or dormancy): This period is sometimes called asymptomatic HIV infection or chronic HIV infection. During this phase, HIV is still active, but reproduces at very low levels. You may not have any symptoms or get sick during this time. People who are on antiretroviral therapy (ART) may live with clinical latency for several decades. For people who are not on ART, this period can last up to a decade, but some may progress through this phase faster. It is important to remember that you are still able to transmit HIV to others during this phase even if you are treated with ART, although ART greatly reduces the risk. Toward the middle and end of this period, your viral load begins to rise and your CD4 cell count begins to drop. As this happens, you may begin to have symptoms of HIV infection as your immune system becomes too weak to protect you.
AIDS (acquired immunodeficiency syndrome): This is the stage of infection that occurs when your immune system is badly damaged and you become vulnerable to infections and infection-related cancers called opportunistic illnesses. When the number of your CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3), you are considered to have progressed to AIDS. (Normal CD4 counts are between 500 and 1,600 cells/mm3.) You can also be diagnosed with AIDS if you develop one or more opportunistic illnesses, regardless of your CD4 count. Without treatment, people who are diagnosed with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year. People with AIDS need medical treatment to prevent death.
Video -HIV Symptoms and Signs
