Human immunodeficiency virus (HIV) is the virus that causes acquired immune deficiency syndrome (AIDS), the most advanced stage of HIV infection. AIDS attacks and destroys the immune system, leaving the infected person vulnerable to illnesses that can lead to death.¹

HIV is spread when infected blood, semen or vaginal secretions come in contact with an uninfected person's broken skin or mucous membranes, including through:³

• Sexual contact with an infected person
• Sharing needles and/or syringes (primarily for drug injection) with an infected person
• Transfusions of infected blood or blood clotting factors (in countries where blood is not screened for HIV antibodies)

Babies born to HIV-infected women may become infected before or during birth or through breast-feeding after birth.

HIV causes AIDS, the most advanced stages of HIV infection. AIDS is identified on the basis of certain infections, grouped by the World Health

• Stage 1: HIV disease is asymptomatic and not categorized as AIDS
• Stage II: Includes minor mucocutaneous manifestations and recurrent upper respiratory tract infections
• Stage III: Includes unexplained chronic diarrhea for longer than a month, severe bacterial infections and pulmonary tuberculosis
• Stage IV: Includes toxoplasmosis of the brain, candidiasis of the esophagus, trachea, bronchi or lungs; and Kaposi's Sarcoma, diseases used as indicators of AIDS

Most of these conditions are opportunistic infections (infections that take advantage of a weakened immune system) that could be treated easily in healthy people.

The only way to know if you are infected is to be tested for HIV infection. You cannot rely on symptoms to know whether or not you are infected with HIV. Many people who are infected with HIV do not have any symptoms at all for many years.³

The following may be warning signs of infection with HIV:³

• Rapid weight loss
• Dry cough
• Recurring fever or profuse night sweats
• Profound and unexplained fatigue
• Swollen lymph glands in the armpits, groin, or neck
• Diarrhea that lasts for more than a week
• White spots or unusual blemishes on the tongue, in the mouth, or in the throat
• Pneumonia
• Red, brown, pink or purplish blotches on or under the skin or inside the mouth, nose or eyelids
• Memory loss, depression and other neurological disorders

Before 1996, scientists estimated that about half the people with HIV would develop AIDS within 10 years after becoming infected. This time varied greatly from person to person and depended on many factors, including a person's health status and their health-related behaviors.³

Since 1996, the introduction of powerful anti-retroviral therapies has dramatically changed the progression time between HIV infection and the development of AIDS. Estimates of how many people will develop AIDS and how soon are being recalculated, revised or are currently under study.³

The only way to know if you are infected is to be tested for HIV infection. You cannot rely on symptoms to know whether or not you are infected with HIV. Many people who are infected with HIV do not have any symptoms at all for many years.³

There is no cure for HIV/AIDS. Progression of the disease can be slowed down but cannot be stopped completely.

HIV/AIDS can be treated with anti-retroviral drugs that work against HIV infection itself by slowing down the reproduction of HIV in the body.¹ The right combination of anti-retroviral drugs can slow down the damage that HIV causes to the immune system and delay the onset of AIDS.¹

However, anti-retroviral drugs are expensive and are often unavailable to patients in developing countries. According to the latest UNAIDS/WHO '3 by 5' progress report, 1 million people living with HIV are currently receiving ARV therapy in developing countries - this means that only 15 percent of those in need of treatment are receiving it.²

The World Health Organization has an initiative to make anti-retroviral drugs available to 3 million AIDS patients by the end of 2005.⁴

No, there is no vaccine and no cure for HIV/AIDS. Progression of the disease can be slowed down but cannot be stopped completely. The right combination of anti-retroviral drugs can slow down the damage that HIV causes to the immune system and delay the onset of AIDS.¹

HIV is transmitted by contact with blood or body fluids of an infected person.³

• There is a high risk (almost 100%) of acquiring HIV through transfusion of infected blood and blood products⁴
• Current estimates suggest that 5 percent to 10 percent of all HIV infections world-wide have been acquired through transfusion of infected blood and blood products⁴
• Annually up to 13 million units of the global blood supply are not screened for HIV or other transfusion-transmissible infections⁴

In the U.S., current estimates are that fewer than 1 in 1.9 million blood components is capable of transmitting HIV.⁵