The human immunodeficiency virus (HIV) seeks and destroys CD4+ cells, a type of T lymphocyte (T cell). T cells are critical to the immune system. They’re responsible for warding off diseases and most infections, including viral infections.
HIV targets the type of cells that would normally fight off an invader like HIV. As the virus replicates, it damages or destroys the infected CD4+ cell and produces more virus to infect more CD4+ cells. Without treatment, this cycle continues in most infected people until the immune system is badly compromised, leaving them open to many serious infections and illnesses. Many of the illnesses that people with compromised immune systems get are rare in people with functioning immune systems.
How quickly the virus progresses varies from person to person. Factors like your age, overall health, and how quickly you’re diagnosed and treated can make a difference.
Acquired immunodeficiency syndrome (AIDS) is the final stage of HIV. At this stage, the immune system is severely weakened, and the risk of contracting opportunistic infections is much greater. Not everyone with HIV will go on to develop AIDS.
Importantly, many of the effects described here are related to the failure of the immune system in progressing HIV and AIDS. Many of these effects are preventable with early antiretroviral treatment, which can preserve the immune system. However, for anyone without access to effective antiretroviral treatment, these effects remain possible.
Your immune system prevents your body from acquiring the diseases and infections that come your way. White blood cells defend you against viruses, bacteria, and other organisms that can make you sick.