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 off infections.

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

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

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

• Contaminated blood transfusions and blood product
• Intimate sexual contac
• The use of contaminated needles and syringes

The virus may also spread from the 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 blood test results to change from HIV negative to HIV positive.

HIV has spread throughout the US. Higher concentrations of the disease are found in inner cities.

HIV can cause any symptoms of illness, since infections can occur throughout the body. Some ymptoms related to HIV infection include:

• Diarrhea
• Fatigue
• Fever
• Frequent vaginal yeast infections
• Headache
• Mouth sores, including candidal 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/Western blot test detects antibodies to the HIV virus. 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/Western blot test is 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.

Doctors often recommend drug therapy for patients who are committed to taking all their medications and have a CD4 count below 350 cells/mL (indicating their immune system is suppressed). Some people, including pregnant women and people with kidney or neurological problems related to HIV, may need treatment regardless of their CD4 count.

It is extremely important for people with HIV to take all doses of their medications, otherwise the virus will quickly become resistant to the drugs. Therapy always involves a combination of antiviral drugs.

People with HIV infection need to become educated about the disease and treatment so that they can be active partners in making decisions with their health care provider.

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 carinii pneumonia (also called Pneumocystis jiroveci 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 IV drugs, avoid sharing needles or syringes. Always use new needles. (Boiling or cleaning them with alcohol does not guarantee that they're sterile.)
• 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 IV 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.