Acquired immune deficiency syndrome(HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV).Following initial infection, a person may not notice any symptoms or may experience a brief period of influenza-like illness.Typically, this is followed by a prolonged period with no symptoms. As the infection progresses, it interferes more with the immune system, increasing the risk of common infections like tuberculosis, as well as other opportunistic infections, and tumors that rarely affect people who have working immune systems.These late symptoms of infection are referred to as AIDS.This stage is often also associated with weight loss.
HIV is spread primarily by unprotected sex(including anal and oral sex), contaminated blood transfusions, hypodermic needles, and from mother to child during pregnancy, delivery, or breastfeeding. Some bodily fluids, such as saliva and tears, do not transmit HIV. Methods of prevention include safe sex, needle-exchange programs,treating those who are infected, and male circumcision.Disease in a baby can often be prevented by giving both the mother and child anti retroviral medication. There is no cure or vaccine; however, anti retroviral treatment can slow the course of the disease and may lead to a near-normal life expectancy.Treatment is recommended as soon as the diagnosis is made.Without treatment, the average survival time after infection is 11 years.