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HIV infection is a disease caused by the human immunodeficiency virus (HIV). The condition gradually destroys the immune system, which makes it harder for the body to fight infections.

This article provides a general overview. For more detailed information, see:

• AIDS
• Acute HIV infection
• Asymptomatic HIV infection
• Early symptomatic HIV infection

Human immunodeficiency virus infection

The human immunodeficiency virus (HIV) can be spread by the following:

• Contaminated blood transfusions and blood products
• Intimate sexual contact
• The use of contaminated needles and syringes

The virus may also spread from a mother to her baby, either at birth or through breastfeeding.

People who become infected with HIV may have no symptoms for up to 10 years, but they can still pass the infection to others. After being exposed to the virus, it usually takes about 3 months for the HIV ELISA blood test to change from HIV negative to HIV positive.

HIV has spread throughout the US. The disease is more prevalent in urban areas, especially in inner cities.

Symptoms related to HIV are usually due to an infection in part of the body. Some symptoms related to HIV infection include:

• Diarrhea
• Fatigue
• Fever
• Frequent vaginal yeast infections
• Headache
• Mouth sores, including fungal (candida) infection
• Muscular stiffness or aching
• Rash of various types, including seborrheic dermatitis
• Sore throat
• Swollen lymph glands

Note: At the time of diagnosis with HIV infection, many people may not have experienced any symptoms.

The HIV ELISA and HIV Western blot tests detect antibodies to the HIV virus in the blood. Having these antibodies means you are infected with HIV.

• If the test is negative (no antibodies found) and you have risk factors for HIV infection, you should be retested in 3 months.
• If the HIV ELISA and HIV Western blot tests are positive, other blood tests can be done to determine how much HIV is in your bloodstream.

White blood cell differential may also show abnormalities.

A lower-than-normal CD4 cell count may be a sign that the virus is suppressing your immune system.

See: AIDS - support group

HIV is a chronic medical condition that can be treated, but not yet cured. There are effective ways to prevent complications and delay, but not prevent, progression to AIDS.

Almost all people infected with HIV will develop AIDS if not treated. However, there is a tiny group of people who develop AIDS very slowly, or never at all. These patients are called long-term non-progressors.

• Cancers
• Chronic wasting (weight loss) from HIV infection
• HIV dementia
• HIV lipodystrophy
• Opportunistic infections
  • Bacillary angiomatosis
  • Candidiasis
  • Cytomegalovirus infection
  • Cryptococcal infection
  • Cryptosporidium enterocolitis (or other protozoal infections)
  • Mycobacterium avium complex (MAC) infection
  • Pneumocystis jiroveci pneumonia (also called Pneumocystis carinii pneumonia)
  • Salmonella infection in the bloodstream
  • Toxoplasmosis
  • Tuberculosis (in the lungs or spread throughout the body)
  • Viral infection of the brain (progressive multifocal leukoencephalopathy)

Call your health care provider if you have had a possible or actual exposure to AIDS or HIV infection.

• Avoid injected (intravenous) drugs. If you use injected drugs, avoid sharing needles or syringes. Always use new needles. (Boiling or cleaning them with alcohol does not guarantee that they're sterile and safe.)
• Avoid oral, vaginal, or anal contact with semen from HIV-infected people.
• Avoid unprotected anal intercourse, since it causes small tears in the rectal tissues, through which HIV in an infected partner's semen may enter directly into the other partner's blood.
• If you have sex with people who use injected drugs, always use protection.
• If you have sex with many people or with people who have multiple partners, always use protection.
• People with AIDS or who have had positive HIV antibody tests can pass the disease on to others. They should not donate blood, plasma, body organs, or sperm. They should not exchange genital fluids during sexual activity.
• Safer sex behaviors may reduce the risk of getting the infection. There is still a slight risk of getting the infection even if you practice "safe sex" with the use of condoms. Abstinence is the only sure way to prevent sexual transmission of the virus.
• Use protection when having sexual contact with people you know or suspect of being infected with HIV. Even better, use protection for ALL sexual contact.

Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007: sect XXIV.