If your blood is positive for HIV, you are infected with HIV. If you are only antibody positive and have no clinical symptoms, you are then called an HIV carrier. AIDS, also known as human immunodeficiency virus, is a virus that specifically attacks human T-lymphocytes, which can cause loss of cellular immune function in humans. Patients are prone to tumors and serious infections because of the loss of cellular immune function and decreased immune surveillance, which is the main reason why HIV causes death in patients. There are three ways of transmission of HIV, including sexual transmission, mother-to-child transmission, and blood transmission. Therefore, HIV testing is required before blood donation, just to prevent HIV-positive patients from infecting healthy people. Before donating blood, HIV, hepatitis B virus and syphilis antibodies are all items that must be routinely checked.