AIDS and HIV Infection

HIV, or human immunodeficiency (HYOO-mun ih-myoo-no-dih-FIH-shen-see) virus, is a virus that can weaken the body's immune system. Infection with HIV causes a life-threatening illness called AIDS, or acquired immunodeficiency syndrome.

What Are AIDS and HIV?

AIDS is the disease caused by human immunodeficiency virus type 1, or HIV-1 (usually referred to as HIV). HIV belongs to the retrovirus family, a group of viruses that have the ability to use cells' machinery to replicate (make more copies of the infecting virus).

HIV attacks the immune system by damaging or killing a specific type of white blood cell in the body called a T-lymphocyte (LIM-fo-site), also called a CD4+ or T-helper cell. T-lymphocytes help the immune system perform its important task of fighting disease in the body caused by invading germs. As a result of HIV infection, the immune system becomes weakened and the body has trouble battling certain infections caused by bacteria, viruses, parasites, and fungi. Many of these infections are highly unusual in people with healthy immune systems. They are called opportunistic infections because they take advantage of a weakened immune system. People with HIV disease not only are more likely to contract these infections, they are more likely to have them repeatedly and to become much more sick from them.

Infection with HIV takes about 10 years to develop into full-blown AIDS. During most of this period, people usually look and feel healthy

The HIV virus attacks T-helper cells, or CD4+ cells, by fitting itself into the cell like a key in a lock. Once it has invaded, it can use its own RNA as a template to make copies of itself, multiplying and traveling through the body. This process destroys the body's own T cells over time; as the T-cell count falls, the body's resistance to germs and disease declines.

Worldwide, about one-third of people with HIV/AIDS are between 15 and 24 years of age. Teens and young adults are at particular risk because they are more likely to have unprotected sex.

AIDS was first described in the United States in 1981, after many gay men in San Francisco and New York City became ill from an unknown infectious cause. In 1985, it became clear that a retrovirus causes AIDS.

How Common Is HIV Infection?

In some areas of the world, such as in sub-Saharan Africa, rates of HIV infection are extremely high and continue to rise rapidly. Worldwide, it is estimated that 42 million people are living with HIV/AIDS. In 2002 alone, 5 million people became infected with HIV, and more than 3 million died from AIDS. Many infected people live in impoverished areas where medicines and other treatments are not available or affordable.

In the United States, HIV infection is less common. According to the U.S. Centers for Disease Control and Prevention (CDC), by the end of 2001 a total of about 816,000 cases of AIDS had been reported and about 468,000 deaths had been attributed to AIDS since the disease was

Since 1987 the AIDS Memorial Quilt (shown here on display in Washington, D.C.) has underscored the devastating impact of the disease. Each of the more than 44,000 panels memorializes the life of someone who has died of AIDS.

Paul Margolies

How Is HIV/AIDS Spread?

HIV/AIDS is contagious from person to person. People can spread the virus before they have developed any symptoms and are unaware they are infected. The HIV virus spreads in certain body fluids, including blood, semen^*, breast milk, vaginal^* fluid, and any other body fluid that contains blood. HIV can spread in the following ways:

• through vaginal, anal, or oral sexual intercourse
• by sharing needles to inject intravenous^* (IV) drugs
• from mother to child in the womb
• during childbirth or breast-feeding
• from any blood-to-blood contact with someone who is infected, such as, in very rare cases, contact with an open wound (though the virus cannot be transmitted unless the skin of both people is broken).

Because it can be difficult to see small breaks in the skin such as hangnails, doctors advise caution when coming into contact with any cut or wound on someone infected with HIV. Medical personnel are at risk of contracting HIV infection through accidental injuries with medical instruments (especially needles and scalpels) that have been contaminated with the blood of an HIV-infected patient.

Sharing living space or items such as eating utensils or clothes does not transmit the virus. Neither does casual contact—doing things like hugging or shaking hands—so there is no need to avoid this type of contact with someone who has HIV. Blood donations and blood products in the United States have been screened for HIV since 1985, and today the blood supply is considered safe. The risk of becoming infected through blood transfusions^* is extremely low.

In 1984, at the onset of the AIDS epidemic, Ryan White became infected with the HIV virus through a blood transfusion. His spirited fight to educate the public about the disease and to end prejudice against people with AIDS ended with his death in 1990 at the age of eighteen.

Corbis Corporation (New York)

What Are the Signs and Symptoms of HIV/AIDS?

Before a person has developed signs of AIDS, it is impossible to tell whether someone is infected with HIV by just looking at that person. People usually develop an illness with symptoms like those of the flu a few weeks after becoming infected with the virus. They may have a fever, a sore throat, muscle aches, and, sometimes, a measles-like rash. This illness usually goes away after a couple of weeks, and other symptoms may not appear for 5 to 15 years. The incubation (ing-kyoo-BAY-shun) period, or amount of time after infection before symptoms appear, varies from person to person.

When symptoms do appear, they might include dry cough, sweating excessively at night, rapid weight loss, recurring fever, pneumonia, white spots or patches on the tongue or throat, headache, persistent diarrhea (dye-uh-REE-uh), memory loss, depression, extreme tiredness, skin rashes, and swollen lymph nodes^*.

How Is HIV/AIDS Diagnosed?

In order to diagnose HIV infection, doctors perform a blood test to look for antibodies^* to the virus. This test may not show signs of infection until several months after infection occurs. Other tests can detect the presence of the virus in the blood directly. The most common of these uses a technique called the polymerase (pah-LIM-er-ace) chain reaction (PCR). Special cultures^* of the blood for HIV or a measurement of p24 antigen (AN-tih-jen), a part of the virus's coat, are available but are used less frequently.

A diagnosis of AIDS is made when a person who is infected with HIV develops certain infections or conditions associated with the disease that indicate a weakening of the immune system. AIDS is also diagnosed when the number of CD4+ T-cells in the body drops below a certain level. The level or "count" of these cells can be measured by taking a blood sample.

About one in four infants born to mothers infected with HIV will be infected with the virus if the mother does not receive treatment during her pregnancy, and the baby after birth, to prevent spread of HIV to the infant. Sometimes infants who are not infected test positive for HIV antibodies in their blood for more than a year because antibodies were passed to the baby through the placenta^* from the mother. Other tests must be done to help determine whether an infant is truly infected.

(1) The human immunodeficiency virus (HIV) particle (top) travels through the bloodstream and (2) attaches to the receptor on the surface of a lymphocyte (bottom), an immune system cell involved in fighting infections. (3) Genetic material (RNA) from the virus enters the lymphocyte and, (4) with the help of an enzyme called reverse transcriptase, makes copies of itself to be inserted into the genetic material of the host lymphocyte. Drugs known as reverse transcriptase inhibitors act at this step to block the virus' genetic material from copying itself. (5) Copies of the virus' genetic material are inserted into the genetic material of the lymphocyte. (6) This new genetic material in the cell causes the lymphocyte to make the "blueprint" needed for manufacturing new HIV particles. This blueprint contains the code for making virus proteins. An enzyme known as a protease acts to clip the large virus protein molecules into smaller pieces so they can be used to make new HIV particles. Drugs known as protease inhibitors work at this step by interfering with the processing of virus protein. (7,8) New HIV particles are produced and released from the lymphocyte, which is destroyed. These viruses can then travel through the body and enter and destroy other cells.

How Is HIV/AIDS Treated?

Receiving treatment as early as possible, before the start of symptoms, increases a person's chances of staying healthier and living longer with HIV infection. Advances in treatment have greatly improved the quality of life, and prolonged life, for many people living with HIV and AIDS. Since the 1980s, various types of medications have been developed to treat AIDS. All of these drugs work by interfering with the replication cycle of HIV; they block the action of certain enzymes^* that the virus needs in order to make copies of itself. Taking these medicines slows the spread of HIV in a person's body, delaying the onset of AIDS. The class of drugs called protease (PRO-tee-aze) inhibitors (the enzyme that the drug blocks is known as a protease) has proven to be especially effective. These drugs and others are most often used in combinations of three to five medications in a treatment known as highly active antiretroviral (an-tie-REH-tro-vy-rul) therapy (HAART). Other medicines also are used to treat or prevent the opportunistic infections associated with HIV infection. The amount of HIV in the body, called the viral load, is followed with regular blood tests to see how well treatment is working. CD4+ (T-helper) cell counts are followed as well. Over time, the virus can develop resistance to the drugs used to fight it and treatment may have to be changed, so research and development of new medicines is essential.

Taking all medications exactly as they are prescribed is crucial because it can help keep resistance to the medicines from developing. Maintaining general good health, getting enough rest, eating a nutritious diet, not smoking or taking drugs, and visiting the doctor for regular checkups are also important parts of treatment.

Currently there is no cure for HIV and AIDS, so once someone becomes infected that person is infected for life. Experts believe that people with AIDS eventually will die from it, unless death from another cause occurs sooner.

Can HIV/AIDS Cause Other Medical Complications?

Complications include AIDS-related opportunistic infections; invasive bacterial infection; certain cancers such as non-Hodgkin's lymphoma, Kaposi's (kuh-POE-zees) sarcoma, and cervical^* cancer; pneumonia; and AIDS dementia (dih-MEN-sha), in which there is impairment of thinking, memory, and concentration. HIV-infected people who use IV drugs are at increased risk for hepatitis^* C infection, which can lead to severe liver damage and death. People with AIDS also are more likely to develop more severe symptoms and complications from other infections such as syphilis^* and tuberculosis^*.

How Can HIV/AIDS Be Prevented?

Researchers are working to develop a vaccine^* for AIDS. Until one is available, the best means of prevention is avoiding contact with the bodily fluids of someone who is infected. This means:

• avoiding sexual contact; this is the only certain way of preventing HIV infection from heterosexual or homosexual sexual contact
• practicing safer sex (using a latex condom properly every time for vaginal, anal, or oral sex), which reduces but does not eliminate the risk of HIV infection; other forms of birth control such as birth control pills offer no protection against the HIV virus
• avoiding IV drug use and never sharing needles for drugs, steroids, medications, tattooing, or body piercing.

For pregnant women infected with HIV, taking antiretroviral drugs during pregnancy and delivering the infant by cesarean section can greatly reduce the risk of a woman passing the infection to her baby. When treatment is given to both mother and infant, the risk of HIV transmission drops by about 75 percent. Doctors also advise that HIV-infected mothers feed their infants formula to prevent passing the virus through breast milk.

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