HIV infection is a condition that can gradually destroy the immune system, which makes it harder for the body to fight infections. When this happens, the person has AIDS (acquired immune deficiency syndrome).
HIV infection; Infection – HIV; Human immunodeficiency virus; Acquired immune deficiency syndrome
Human immunodeficiency virus (HIV) causes HIV infection and AIDS. The virus attacks the immune system. As the immune system weakens, the body is vulnerable to life-threatening infections and cancers. Once a person has the virus, it stays inside the body for life.
The virus is spread (transmitted) person-to-person in any of the following ways:
Through sexual contact -- including oral, vaginal, and anal sex
Through blood -- via blood transfusions (now extremely rare in the U.S.) or needle sharing
From mother to child -- a pregnant woman can spread the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby through her breast milk
The virus is not spread by:
Casual contact such as hugging
Participating in sports
Touching items that were touched by a person infected with the virus
HIV and blood or organ donation:
HIV is not spread to a person who donates blood or organs. People who donate organs are never in direct contact with people who receive them. Likewise, a person who donates blood is never in contact with the person receiving it. In all these procedures, sterile needles and instruments are used.
But HIV can be spread to a person receiving blood or organs from an infected donor. To reduce this risk, blood banks and organ donor programs check (screen) donors, blood, and tissues thoroughly.
People at high risk of getting HIV include:
Injection drug users who share needles
Infants born to mothers with HIV who did not receive HIV treatment during pregnancy
People who have unprotected sex, especially with people who have other high-risk behaviors, are HIV-positive, or have AIDS
People who received blood transfusions or clotting products between 1977 and 1985, before screening for the virus became standard practice
Sexual partners of those who engage in high-risk activities (such as injection drug use or anal sex)
After HIV infects the body, the virus has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid, which is the liquid that comes out before ejaculation), vaginal fluid, and breast milk. Only blood, semen, vaginal secretions, and breast milk have been shown to transmit infection to others.
Symptoms related to acute HIV infection (when a person is first infected) are often flu-like:
Mouth sores, including yeast infection (thrush)
Muscle stiffness or aching
Rashes of different types
Swollen lymph glands
Many people have no symptoms when they are diagnosed 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 can still spread the virus to others.
Almost all people infected with HIV, if they are not treated, will develop AIDS. A small group of patients develop AIDS very slowly or never at all. These patients are called nonprogressors. Many seem to have genes that prevent the virus from significantly damaging their immune system.
People with AIDS have had their immune system damaged by HIV. They are very susceptible to (easily get) infections that do not normally develop in people with a healthy immune system. These infections are called opportunistic infections.
Persons with AIDS usually have regular blood tests to check their CD4 cell count. CD4 cells are a type of T cell. T cells are one kind of cell of the immune system. They are also called "helper cells." A CD4 cell count that is lower than normal may be a sign that the virus is damaging the immune system. (A normal CD4 count is from 500 to 1,500 cells/mm3 of blood.)
When the CD4 count gets too low, the risk of infections and some types of cancer increases.
Other tests that may be done include:
HIV RNA level, or viral load, to check how much virus is in the blood
Pap smear to check for cervical cancer
Anal pap smear to check for cancer of the anus
There is no cure for AIDS at this time. But treatments are available to manage symptoms. Treatment can also improve the quality and length of life for those who have already developed symptoms.
Antiretroviral therapy suppresses the replication of the HIV virus in the body. A combination of antiretroviral drugs, called antiretroviral therapy (ART), also known as highly active antiretroviral therapy (HAART), is very effective in reducing the amount of HIV in the bloodstream. This is measured by the viral load (how much free virus is found in the blood). Preventing the virus from reproducing (replicating) can improve T-cell counts and help the immune system recover from HIV infection.
People on ART with suppressed levels of HIV can still transmit the virus to others through sex or by sharing needles. With ART, if the level of HIV remains suppressed and CD4 count remains high (above 200 cells/mm3), life can be prolonged and improved.
HIV can become resistant to one combination of ART. This is most true in patients who do not take their medications on schedule every day. Tests can check whether an HIV strain is resistant to a particular drug. This information can be useful in finding the best drug combination and for adjusting the drug combination when it starts to fail.
When HIV becomes resistant to HAART, other drug combinations must be used to try to suppress the resistant HIV strain of HIV. There are a variety of new drugs on the market for treating drug-resistant HIV.
Treatment with ART has complications. Each drug has its own side effects. Common side effects are:
Collection of fat on the back (buffalo hump) and abdomen
General sick feeling ( malaise)
When used for a long time, these drugs increase the risk of heart attack, perhaps by increasing the levels of cholesterol and glucose (sugar) in the blood.
Persons on ART are monitored by their health care provider for possible side effects. Blood tests measuring CD4 counts and HIV viral load will likely be done every 3 months. The goal is to get the CD4 count close to normal and to suppress the amount of HIV virus in the blood to a level where it cannot be detected.
Medicines may be prescribed to treat problems related to AIDS such as anemia, low white cell count, and to prevent opportunistic infections.
Joining a support group where members share common experiences and problems can often help the emotional stress of having a long-term illness.
At this time, there is no cure for AIDS. It is always fatal without treatment. In the U.S., most patients survive many years after diagnosis because of treatment with HAART. New medicines are continually being developed.
When a person is infected with HIV, the virus slowly begins to destroy that person's immune system. How fast this occurs differs in each individual. Treatment with HAART can help slow or halt the destruction of the immune system.
Once the immune system is severely damaged, that person has AIDS, and can now get infections and cancers that most healthy persons would not get. Doctors have found that when CD4 falls below certain counts, specific types of infections and cancers can develop.
When to Contact a Medical Professional
Call for an appointment with your health care provider if you have any of the risk factors for HIV infection. Also call if you develop symptoms of AIDS. By law, the results of HIV testing must be kept confidential. Your health care provider will review test results with you.
Do not use illegal drugs and do not share needles or syringes. Many communities now have needle exchange programs, where you can get rid of used syringes and get new, sterile ones. These programs can also refer you for addiction treatment.
Avoid contact with another person's blood. If possible, wear protective clothing, masks, and goggles when caring for people who are injured.
If you test positive for HIV, you can pass the virus to others. You should not donate blood, plasma, body organs, or sperm.
HIV-positive women who plan to get pregnant should talk to their health care provider about the risk to their unborn child. They should also discuss methods to prevent their baby from becoming infected, such as taking medicines during pregnancy.
Breastfeeding should be avoided to prevent passing on HIV to infants through breast milk.
Safer sex practices, such as using latex condoms, are effective in preventing HIV transmission. But there is a risk of getting the infection, even with the use of condoms. Abstinence is the only sure way to prevent sexual transmission of HIV.
HIV-positive patients who are taking antiretroviral medicines are less likely to transmit the virus.
The U.S. 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 can reduce the chances 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 needle sticks.
Quinn TC. Epidemiology of human immunodeficiency virus infection and acquired immunodeficiency syndrome. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, Pa.: Elsevier Saunders; 2011:chap 392.
Sterling TR, Chaisson RE. General clinical manifestations of human immunodeficiency virus infection (including the acute retroviral syndrome and oral, cutaneous, renal, ocular, metabolic, and cardiac diseases). In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa.: Elsevier Churchill-Livingstone; 2009:chap 121.
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. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.