HIV and AIDS

HIV is the human immunodeficiency virus that causes AIDS. A member of a group of viruses called retroviruses, HIV infects human cells and uses the energy and nutrients provided by those cells to grow and reproduce. AIDS (acquired immunodeficiency syndrome) is a disease in which the body's immune system breaks down and is unable to fight off certain infections, known as "opportunistic infections," and other illnesses that take advantage of a weakened immune system. When a person is infected with HIV, the virus enters the body and lives and multiplies primarily in the white blood cells. These are the immune cells that normally protect us from disease.

The hallmark of HIV infection is the progressive loss of a specific type of immune cell called T-helper or CD4 cells. As the virus grows, it damages or kills these and other cells, weakening the immune system and leaving the individual vulnerable to various opportunistic infections and other illnesses, ranging from pneumonia to cancer. The U.S. Centers for Disease Control and Prevention (CDC) defines someone as having a clinical diagnosis of AIDS if they have tested positive for HIV and meet one or both of these conditions: They have experienced one or more AIDS-related infections or illnesses; The number of CD4 cells has reached or fallen below 200 per cubic millimeter of blood (a measurement known as T-cell count). In healthy individuals, the CD4 count normally ranges from 450 to 1200.

In some people, the T-cell decline and opportunistic infections that signal AIDS develop soon after infection with HIV. Most people remain asymptomatic for 10 to 12 years, and a few for much longer. As with most diseases, early medical care can help prolong a p...

... middle of paper ...

...have become highly resistant to current drugs, and as many as 10% of newly infected Americans are acquiring drug-resistant strains of the virus.

Because treatment regimens are unpleasant and complex, many patients miss doses of their medication.

Failure to take anti-HIV drugs on schedule and in the prescribed dosage encourages the development of new viral strains that are resistant to current HIV drugs. Even among those who do respond well to treatment, HAART does not eradicate HIV. The virus continues to replicate at low levels and often remains hidden in "reservoirs" in the body, such as the lymph nodes and brain. In the U.S., the number of AIDS-related deaths has decreased dramatically because of widely available potent treatment. But more than 95% of all people with HIV/AIDS live in the developing world, where access to treatment may be limited at best.