HIV & AIDS Quiz: HIV Testing & Symptoms

HIV, or human immunodeficiency virus, can lead to AIDS (acquired immune deficiency syndrome). Once HIV infection occurs, it persists for life.

A chimpanzee version of the HIV virus, known as simian immunodeficiency virus (SIV), was believed to be transmitted to humans when chimpanzees were hunted for meat in West Africa, causing humans to come into contact with blood of the infected animals. After humans acquired it, the virus is believed to have mutated (changed its genetic material) to its present form. This transfer to humans may have taken place as early as the late 1800s. The virus spread across Africa and finally to other parts of the world.

AIDS refers to acquired immune deficiency syndrome, which is the last or final stage of HIV infection. In AIDS, the immune system is so compromised that opportunistic infections (infections that occur in immunosuppressed people) occurs. Not everyone with HIV infection will develop AIDS. People with AIDS require lifelong medical treatment. If untreated, people with AIDS usually survive about 3 years.

T cells are a type of lymphocyte (one of the white blood cells involved in the body's immune response), which circulate in the blood and play a critical role in the immune response. While there are many kinds of T cells, the two main types are killer T cells and helper T cells. Killer T cells destroy cells that are infected or cancerous, while helper T cells are involved in signaling to coordinate the immune response.

Opportunistic infections occur in people whose immune systems do not function well; these infections would often not cause problems for healthy individuals. Opportunistic infections are more common in people with HIV, but they are less common now than in the early days of the HIV epidemic due to improved treatment protocols.

The HIV virus targets T cells, infecting them and making more copies of the virus. After a long period of time (sometimes many years) without treatment, the virus destroys the infected T cells so the immune function of the body is compromised. CD4 cells are a type of T cell targeted by the HIV virus. When CD4 cell counts become very low (below 200 cells per cubic millimeter of blood [200 cells/mm3]), AIDS is present.

HIV is spread among humans by certain fluids, including blood, semen, breast milk, vaginal secretions, rectal fluids, and pre-seminal fluid. The infected fluid must come in contact with a skin break or mucous membrane of the healthy person in order for infection to occur. Contamination of the bloodstream (e.g. by a needle or syringe from an infected person) can also spread the virus. HIV is not spread by urine or contact with urine from an infected person.

In the U.S., about one-fourth (25%) of people with HIV/AIDS are 50 years of age or older. Improvements in treatment protocols have helped people with AIDS live longer, and HIV infection is being found more commonly in older people.

Being HIV-positive means testing has proven someone has been infected with the HIV virus. It does not mean the person has AIDS. People who are HIV-positive are able to transmit the virus to others, even if they do not yet have any symptoms from the infection.

Medications that have been developed since the identification of HIV have allowed the condition to be managed. People with HIV infection can live a healthy life. It is important to follow the treatment plan as prescribed by your doctor to slow the progression of the infection and to prevent AIDS-related conditions.