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.
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.
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.
These are tests that are done to check if you've been infected with the virus. In general, testing is a 2-step process:
Home tests are available to test for HIV. If you plan to use one, check to make sure it is approved by the FDA. Follow instructions on the packaging to ensure the results are as accurate as possible.
The Centers for Disease Control and Prevention (CDC) recommends that everyone ages 15 to 65 have a screening test for HIV. People with risky behaviors should be tested regularly. Pregnant women should also have a screening test.
TESTS AFTER BEING DIAGNOSED WITH HIV
People with AIDS usually have regular blood tests to check their CD4 cell count:
Other tests include:
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 call 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 drug called Truvada 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.
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 11/05/2018.