Human Immunodeficiency Virus and AIDS
AIDS is the advanced manifestation of infection by thehuman immunodeficiency virus (HIV), an RNA retrovirus. The virus targets “helper” T cells (those with the CD4 marker) and monocytes. Depletion of these CD4 cells is an important manifestation of HIV infection. Two types of HIV have been identified. HIV-1 is the most common type in the United States, while HIV-2 is more common in West African countries. The progression of HIV-1 infec-tion varies from individual to individual. In addition to depletion in the number of CD4 cells, HIV-1 may weaken the immune function of these cells. Both lead to immune-system compromise that leaves the body vulnerable to seri-ous, often life-threatening infections from other bacteria, viruses, and parasites.
It is estimated that 1.2 million individuals in the United States are living with HIV or AIDS. AIDS is now one of the top five causes of death in reproductive-age women. The proportion of all AIDS cases reported among adult and adolescent women in the United States has more than tripled, from 7% in 1985 to 27% in 2004. AIDS is the third leading cause of death in black women of ages 24 to 44 years, and the fourth leading cause of death in Hispanic women in the same age group. The three primary methodsof contracting the virus are: (1) intimate sexual contact, (2) use of contaminated needles or blood products, and (3) perinatal transmission from mother to child. HIV transmission inpregnancy has been greatly reduced as a result of routine screening in the first trimester as well as aggressive ther-apy at the time of delivery. Viral loads are calculated at the time of labor and most infants born to HIV-infected mothers are delivered via cesarean birth.
The screening test for AIDS is an enzyme-linked immunosorbent assay (ELISA) that tests for antibodies against HIV. Although rare, false-positive tests are possible and are more common in multiparous women and women taking oral contraceptives. Confirmation is achieved with the more specific Western blot technique.
Management of HIV focuses on prevention and chemotherapy. Prevention emphasizes use of latex con-doms and safe sex practices. Drug therapy for HIV infec-tion includes various classes of anti-HIV drugs, including the nucleoside reverse transcriptase inhibitors (NRTIs) such as zidovudine, nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors. Mono-therapy is not advocated because of development of drug resistance. Instead, highly active antiretroviral therapy (HAART) consisting of at least three agents has been recommended.