infections
Human Immunodeficiency Virus (HIV) Infection
Introduction
Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and is treated with antiretroviral medications. If untreated, it can cause acquired immunodeficiency syndrome (AIDS). HIV is transmitted through exchange of bodily fluids (semen, vaginal fluid, blood, breast milk) with an infected person, usually through vaginal or anal sex, sharing needles, or from mother to child (during pregnancy, birth, or breastfeeding). HIV destroys certain types of white blood cells, weakening the body’s defenses against infections and cancers. When people are first infected, symptoms of fever, rashes, swollen lymph nodes, and fatigue may last a few days to several weeks, and then they may have no symptoms for more than a decade. Blood tests to check for HIV antibody and to measure the amount of HIV virus can confirm the diagnosis. HIV screening tests are available for adults and adolescents, particularly pregnant women, regardless of what their risk appears to be. HIV medications (antiretroviral medications) can stop HIV from reproducing, allow the immune system to strengthen, and thus allow people to live without severe infections or HIV-related cancers. Most untreated people eventually become ill and develop AIDS, defined by the presence of serious infections and cancers. (See also Human Immunodeficiency Virus (HIV) Infection in Children and Adolescents .) HIV infections may be caused by one of two retroviruses, HIV-1 or HIV-2. HIV-1 causes most HIV infections worldwide, but HIV-2 causes many HIV infections in West Africa. Infection with another type of retrovirus, human T-lymphotropic virus (HTLV), is less common but can also cause serious disease. The human immunodeficiency virus (HIV) is a retrovirus, which, like many other viruses, stores its genetic information as Transcription and translation rather than as When HIV enters a human cell, it releases its RNA, and an enzyme called reverse transcriptase makes a DNA copy of the HIV RNA. The resulting HIV DNA is integrated into the infected cell’s DNA. This process is the reverse of that used by human cells, which make an RNA copy of DNA. Thus, HIV is called a retrovirus, referring to the reversed (backward) process. Other RNA viruses (such as polio, influenza, or measles), unlike retroviruses, do not make DNA copies after they invade cells. They simply make RNA copies of their original RNA. Each time an HIV-infected cell divides, it makes a new copy of the integrated HIV DNA as well as its own genes. The HIV DNA copy is either Inactive (latent):The virus is present but does no damage. Activated:The virus takes over the functions of the infected cell, causing it to produce and release many new copies of HIV, which then invade other cells. lymphocytes. Lymphocytes help defend the body against foreign cells, infectious organisms, and cancer. Thus, when HIV destroys CD4 HIV-1 originated in Central Africa during the first half of the 20th century when a closely related chimpanzee virus first infected people. The global spread of HIV-1 began in the late 1970s, and AIDS was first recognized in 1981. In 2021, approximately 38 million people, including 1.7 million children under age 15, were living with HIV infection worldwide two thirds of whom (25.6 million) are in the Sub-Saharan African Region. 650,000 people died from AIDS-related illnesses worldwide, compared to 1.9 million in 2004 and 1.4 million in 2010. 1.5 million people were newly infected with HIV, of whom approximately 860,000 (57%) were in sub-Saharan Africa. 85% of people living with HIV in 2021 knew their HIV status, and 75% were accessing treatment. Through international efforts, as of 2021, an estimated 28.7 million people living with HIV were accessing antiretroviral therapy (up from 7.8 million in 2010), dramatically reducing deaths and transmission in many countries. In the United States at the end of 2019, an estimated 1,189,700 people aged 13 years or older were estimated to have HIV infection, including an estimated 158,500 (13%) people whose infections had not been diagnosed. In 2020, over 30,600 people received an HIV diagnosis in the United States, and 20,758 cases were due to male-to-male sexual contact. Data for 2020 should be interpreted with caution due to the impact of the COVID-19 pandemic on access to HIV testing, care-related services, and case surveillance activities. 