Human immunodeficiency virus, or
HIV, is the virus that causes acquired immune deficiency syndrome (
AIDS). The virus weakens a person's ability to fight infections and
cancer. People with HIV are said to have AIDS when they develop certain infections or cancers or when their CD4 count is less than 200. CD4 count is determined by a blood test in a doctor's office.
Having HIV does not always mean that you have AIDS. It can take many years for people with the virus to develop AIDS. HIV and AIDS cannot be cured. Although people with AIDS will likely one day die from an AIDS-related illness, there are ways to help people stay healthy and live longer.