Acquired immune deficiency syndrome (AIDS) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV). It is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as: blood, semen, vaginal fluid and breast milk. There is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection. Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS epidemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.