HIV, the human immunodeficiency virus, is the virus that causes AIDS. This disease suppresses the body's ability to fight infections and weakens the immune system by killing vital T-cells, according to WebMD.
HIV is a global health epidemic and has killed over 39 million people worldwide, according to the World Health Organization. As of 2013, WHO estimates that over 35 million people live with HIV worldwide. Most of these people live in low-income and developing countries. Sub-Saharan Africa accounts for almost 70 percent of new HIV infections.
HIV transmits through unprotected sexual intercourse, through sharing of contaminated needles and between an infected mother and her baby during pregnancy and breastfeeding, according to WHO. People can not get infected through casual contact, such as kissing, shaking hands or sharing personal objects with a person with HIV.
After a person is infected, there is an incubation period in which there are no symptoms present. This period can last from a few months to 10 years, according to WebMD.
Although there is no cure for HIV, combination antiretroviral drugs control viral replication and help the immune system regain strength. These drugs drastically improve life expectancy and quality of life for people living with HIV, according to WHO.