The human immunodeficiency virus (HIV) is a virus that attacks the immune system. Left untreated, HIV can progress within a few years and lead to acquired immune deficiency syndrome (AIDS), a set of symptoms and infections that eventually cause death.
Although HIV is not yet curable, it is very treatable. Taking proper treatment consistently and leading a healthy lifestyle enables most people with HIV to live a normal life span.
HIV is a type of virus that infects a specific type of immune system cell: CD4 lymphocytes or T-helper cells. The role of healthy CD4 cells is to send signals to other immune cells, telling them to start fighting off infections in your body. When HIV infects a CD4 cell, it hijacks the process by which the cell replicates itself and uses it to produce copies of HIV instead. These copies are released into the body to infect more CD4 cells. HIV also destroys CD4 cells, weakening the immune system and leaving the body unable to rally an effective response to cancer and infection.
HIV is passed by specific types of contact with infected blood, semen, preseminal fluid, vaginal secretions, and rectal fluid. The virus can also be transmitted from mother to child during childbirth or pregnancy or through breastfeeding and breast milk. In order to infect someone, the infected fluid must come into contact with their bloodstream, a mucous membrane, or damaged tissue such as an open wound.
HIV is most commonly passed during anal or vaginal sex without condoms or by sharing used needles or other injection equipment. However, it is important to clarify that the virus is not transmitted through casual or everyday contact, such as through sharing drinks or kissing.
Scientists identified AIDS in the United States in 1981, although it was not well understood at the time. Doctors scrambled to figure out how AIDS was spread and how to stop it. It would take years to piece together that HIV infection leads to AIDS, and many more years to undo the myth that HIV could only affect gay men.
Researchers now know that HIV originated in Kinshasa, Democratic Republic of Congo, in 1920 when HIV crossed species from chimpanzees to humans. By 1980, HIV had already spread to five continents: North America, South America, Europe, Africa, and Australia. The first cases were presented to the Centers for Disease Control and Prevention (CDC) in 1981. Five previously healthy gay men in Los Angeles had acquired a rare lung infection called Pneumocystis carinii pneumonia and other infections. The CDC began to receive more reports of severe immune deficiency among gay men. By the end of 1981, there were 270 reported cases of the mysterious disease and 121 deaths.
The media began to raise an alarm that AIDS affected gay men. Some researchers dubbed the condition “gay-related immune deficiency” or “GRID,” furthering and worsening the stigma. Cities like San Francisco and New York began campaigns to close bath houses and private sex clubs. The U.S. imposed a travel ban to stop immigrants with AIDS from entering the United States.
It would take years for researchers to realize that anyone, regardless of age, gender, or sexual orientation could be infected with HIV and that it could spread in ways other than through sex, such as shared needles.
In 1982, a nonprofit called the World Federation of Hemophilia presented evidence to the CDC and blood-banking companies that AIDS may be a blood-borne disease. The CDC rejected this claim due to “lack of research,” and blood-banking companies refused to change the way they screened donors. At that time, CDC scientists still wrongly believed that AIDS only affected homosexual males and was not an infectious disease. Screening for HIV would not begin at blood banks until 1985.
Between 1981 and 1985, half of the population of hemophilia patients in the U.S. was infected with HIV because of tainted blood products, which contained pooled plasma from thousands of donors. AIDS rates in Europe during this time were estimated to be as high as 80 percent or 90 percent of the hemophilia A population.
In 1986, the International Committee on the Taxonomy of Viruses officially designated the virus that causes AIDS as “human immunodeficiency virus.” Scientists realized that HIV is a virus that can be passed between any humans and AIDS is the final stage of the infection, developing later as the immune system becomes weak.
The U.S. Food and Drug Administration (FDA) approved the first antiretroviral therapy (ART) treatment, zidovudine (available today in combination drugs including Combivir, Retrovir, and Trizivir), as treatment for HIV in March 1987. Antiretroviral drugs could prevent people with HIV from developing AIDS.
The stigma of HIV was slow to be corrected. In 1990, the U.S. enacted the Americans With Disabilities Act (ADA), which prohibited discrimination against people with disabilities, including those with HIV. It wasn’t until 2010 that the travel ban barring HIV-positive people from entering the U.S. was lifted. High-profile celebrities with HIV such as NBA All-Star Earvin “Magic” Johnson helped dispel stereotypes.
Ryan White, a teenager from Indiana, acquired HIV after a blood transfusion. White faced discrimination and became a prominent activist for the rights and dignity of those with AIDS. White was banned from attending school due to stigma and fear of HIV infection, but his mother fought his case in court and won. On April 8, 1990, Ryan died of an AIDS-related illness at age 18. President George H.W. Bush signed the Ryan White CARE Act into law in August 1990, allocating $2 billion to fight HIV/AIDS.
The FDA approved the first protease inhibitor, saquinavir (Invirase), in 1995. The new class of ART drugs is credited with an immediate decline between 60 percent and 80 percent in rates of AIDS-related deaths and hospitalization in countries with access to treatment.
In July 2012, the FDA approved preexposure prophylaxis (PrEP) medication regimen to prevent HIV-negative people with a high risk from becoming infected with HIV. PrEP can reduce the risk of becoming infected with HIV by sexual contact by more than 90 percent and from intravenous drug use by 70 percent, according to the CDC.
By 2017, more than half of the global population with HIV — over 19.5 million people — was receiving antiretroviral treatment. Global HIV advocacy organizations started to promote the slogan “Undetectable = Untransmittable” (or “U=U”). This anti-stigma campaign is based on scientific evidence that people with HIV who achieve an undetectable viral load while on treatment cannot pass the virus to others.
As of 2023, an estimated 1.2 million people ages 13 in up in the U.S. are living with HIV — and about about 14 percent of them (1 in 7 people) don’t know they have the virus.
Gay men, bisexual men, and other men who have sex with men represent the demographics most affected by HIV, according to HIV.gov. Of the 30,635 new HIV diagnoses in the U.S. in 2020, 68 percent were among gay and bisexual men, per the CDC. Transgender women who have sex with men also are among the groups at highest risk for HIV infection, according to HIV.gov.
People in their 20s and 30s are more likely to be diagnosed with HIV than those in other age groups.
In the U.S., “Blacks/African Americans and Hispanics/Latinos are disproportionately affected by HIV compared to other racial and ethnic groups,” according to HIV.gov.
Doctors can detect HIV with blood tests or testing oral fluids (similar to saliva). For the most accurate diagnosis, a doctor needs to perform the most sensitive diagnostic tests available. Home HIV tests are also available. For people who test positive, a doctor may conduct further tests to check for infections that can occur as complications of HIV.
Learn more about how HIV is diagnosed.
HIV symptoms vary by the stage of HIV infection. An estimated 10 percent to 60 percent of individuals with early HIV infection will not experience symptoms. In the other cases, a person may experience flu-like symptoms — known as the acute retroviral syndrome — within one or two months after becoming infected. Symptoms generally last a few weeks and can include fever, sore throat, rash, diarrhea, weight loss, and headache.
During the chronic or latent stage — which lasts approximately 10 to 15 years without treatment — a person may experience swollen lymph nodes or no symptoms at all. By sticking to their recommended treatment regimen, most people with HIV will never experience progression of the disease. Without treatment, HIV progresses to a symptomatic phase, characterized by frequent infections, fever, fatigue, sweats, diarrhea, and weight loss.
In the final stage of HIV, known as AIDS, a person has a severely compromised immune system, leading to severe infections and cancers that eventually cause death.
HIV is treated with antiretroviral therapy. There are many different classes of ART medications, and most people are treated with a combination of drugs from more than one class. Certain types of preventative ART can also protect against transmission. Infections that develop as a complication of HIV may be treated with antibiotics, antifungals, and other classes of antiviral medications.
Learn more about HIV treatments.
There is no cure for HIV or AIDS. However, treatments for HIV are so effective that they prevent AIDS from developing in nearly every case. Treatments can also effectively lower the risk of transmitting HIV between sexual partners.
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