When testing for hepatitis B, the first test is the hepatitis B two-to-one half. If the hepatitis B two-to-one half test is positive for hepatitis B surface antigen, the person is initially identified as a carrier of the hepatitis B virus, and then the hepatitis B virus HBV-DNA is further examined to determine the hepatitis B virus load. For syphilis screening, specific and non-specific antibodies to syphilis are checked. For HIV test, the HIV antibody is checked first. The HIV antibody test is used as a primary screening test, and then a confirmatory test is performed if the HIV antibody is positive, and if the confirmatory test is still positive, the diagnosis of HIV is confirmed. The HIV test also includes CD4+ T lymphocyte test, because after HIV infection, it mainly attacks the most important CD4+ T lymphocytes in the human immune system, so the CD4+ T lymphocytes will drop significantly in AIDS. Hepatitis B, syphilis, and AIDS can be transmitted through the bloodstream, and syphilis and AIDS are most commonly transmitted through sexual contact.