Human immunodeficiency virus (HIV) is the virus that causes AIDS. When a person becomes infected with HIV, the virus attacks and weakens the immune system. As the immune system weakens, the person is at risk of getting life-threatening infections and cancers. When that happens, the illness is called AIDS. Once a person has the virus, it stays inside the body for life.
HIV infection; Infection - HIV; Human immunodeficiency virus; Acquired immune deficiency syndrome: HIV-1
The virus is spread (transmitted) person-to-person through certain body fluids:
HIV can be spread if these fluids come in contact with:
HIV cannot be spread through sweat, saliva, or urine.
In the United States, HIV is mainly spread:
Less often, HIV is spread:
The virus is NOT spread by:
HIV and blood or organ donation:
Risk factors for getting HIV include:
Symptoms related to acute HIV infection (when a person is first infected) can be similar to the flu or other viral illnesses. They include:
Many people have no symptoms when they are first infected with HIV.
Acute HIV infection progresses over a few weeks to months to become an asymptomatic HIV infection (no symptoms). This stage can last 10 years or longer. During this period, the person might have no reason to suspect they have HIV, but they can spread the virus to others.
If they are not treated, almost all people infected with HIV will develop AIDS. Some people develop AIDS within a few years of infection. Others remain completely healthy after 10 or even 20 years (called long-term nonprogressors).
People with AIDS have had their immune system damaged by HIV. They are at very high risk of getting infections that are uncommon in people with a healthy immune system. These infections are called opportunistic infections. These can be caused by bacteria, viruses, fungi, or protozoa, and can affect any part of the body. People with AIDS are also at higher risk for certain cancers, especially lymphomas and a skin cancer called Kaposi sarcoma.
Symptoms depend on the particular infection and which part of the body is infected. Lung infections are common in AIDS and usually cause cough, fever, and shortness of breath. Intestinal infections are also common and can cause diarrhea, abdominal pain, vomiting, or swallowing problems. Weight loss, fever, sweats, rashes, and swollen lymph glands are common in people with HIV infection and AIDS.
HIV/AIDS is treated with medicines that stop the virus from multiplying. This treatment is called antiretroviral therapy (ART).
In the past, people with HIV infection would start antiretroviral treatment after their CD4 count dropped or they developed HIV complications. Today, HIV treatment is recommended for all people with HIV infection, even if their CD4 count is still normal.
Regular blood tests are needed to make sure the virus level in the blood (viral load) is kept low or suppressed. The goal of treatment is to lower the HIV virus in the blood to a level that is so low that the test can't detect it. This is called an undetectable viral load.
If the CD4 count already dropped before treatment was started, it will usually slowly go up. HIV complications often disappear as the immune system recovers.
Joining a support group where members share common experiences and problems can often help lower the emotional stress of having a long-term illness.
With treatment, most people with HIV/AIDS can live a healthy and normal life.
Current treatments do not cure the infection. The medicines only work as long as they are taken every day. If the medicines are stopped, the viral load will go up and the CD4 count will drop. If the medicines are not taken regularly, the virus can become resistant to one or more of the drugs, and the treatment will stop working.
People who are on treatment need to see their health care providers regularly. This is to make sure the medicines are working and to check for side effects of the drugs.
Call for an appointment with your provider if you have any risk factors for HIV infection. Also contact your provider if you develop symptoms of AIDS. By law, the results of HIV testing must be kept confidential (private). Your provider will review your test results with you.
Safer sex practices, such as using latex condoms, are effective in preventing the spread of HIV. But there is still a risk of getting the infection, even with the use of condoms (for example, condoms can tear).
In people who aren't infected with the virus, but are at high risk of getting it, taking a medicine such as Truvada (emtricitabine and tenofovir disoproxil fumarate) or Descovy (emtricitabine and tenofovir alafenamide) can help prevent the infection. This treatment is known as pre-exposure prophylaxis, or PrEP. Talk to your provider if you think PrEP might be right for you.
HIV-positive people who are taking antiretroviral medicines and have no virus in their blood do not transmit the virus.
The US blood supply is among the safest in the world. Nearly all people infected with HIV through blood transfusions received those transfusions before 1985, the year HIV testing began for all donated blood.
If you believe you have been exposed to HIV, seek medical attention right away. DO NOT delay. Starting antiviral medicines right after the exposure (up to 3 days after) can reduce the chance that you will be infected. This is called post-exposure prophylaxis (PEP). It has been used to prevent transmission in health care workers injured by needlesticks.
Centers for Disease Control and Prevention website. About HIV/AIDS. www.cdc.gov/hiv/basics/whatishiv.html. Reviewed November 3, 2020. Accessed November 11, 2020.
Centers for Disease Control and Prevention website. PrEP. www.cdc.gov/hiv/basics/prep.html. Reviewed November 3, 2020. Accessed April 15, 2019. DiNenno EA, Prejean J, Irwin K, et al. Recommendations for HIV screening of gay, bisexual, and other men who have sex with men - United States, 2017. MMWR Morb Mortal Wkly Rep. 2017;66(31):830-832. www.cdc.gov/mmwr/volumes/66/wr/mm6631a3.htm.
Gulick RM. Antiretroviral therapy of human immunodeficiency virus and acquired immunodeficiency syndrome. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 364.
Moyer VA; US Preventive Services Task Force. Screening for HIV: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2013;159(1):51-60. PMID: 23698354 pubmed.ncbi.nlm.nih.gov/23698354/.
Reitz MS, Gallo RC. Human immunodeficiency viruses. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 169.
Simonetti F, Dewar R, Maldarelli F. Diagnosis of human immunodeficiency virus infection. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 120.
US Department of Health and Human Services, Clinical Info.gov website. Guidelines for the use of antiretroviral agents in adults and adolescents living with HIV. clinicalinfo.hiv.gov/en/guidelines/adult-and-adolescent-arv/whats-new-guidelines?view=full. Updated July 10, 2019. Accessed November 11, 2020.
Verma A, Berger JR. Neurological manifestations of human immunodeficiency virus infection in adults. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 77.