What are HIV and AIDS?

What is HIV?

Human immunodeficiency virus, or HIV, is the virus that causes AIDS. It attacks the body's immune system. By weakening the body's defences against disease, HIV makes the body vulnerable to a number of potentially life-threatening infections and cancers. HIV is infectious, which means it can be transmitted from one person to another.

What happens in the body when HIV infection occurs?

HIV infects white blood cells, which are part of the body's immune system. A strong immune system is needed to fight off a range of infections. When a person is infected with HIV, cells are infected by the virus and, over time, the immune system becomes progressively less able to fight off disease.

Soon after HIV infection occurs, the body's immune system mounts an attack against the virus by means of specialized killer cells and antibodies that usually succeed in temporarily lowering the amount of virus in the blood. But HIV still remains active, continuing to infect and kill vital cells of the immune system. HIV also establishes reservoirs within the body that cannot be destroyed by the available antiretroviral medicines. Without treatment, viral activity significantly increases over time, eventually overwhelming the body's ability to fight off disease.

What is AIDS?

If left untreated, HIV will almost always deplete the immune system, leaving the body vulnerable to one or more life-threatening diseases that normally do not affect healthy people. This stage of HIV infection is called AIDS, or acquired immunodeficiency syndromeThe more the immune system has been damaged, the greater the risk of death from opportunistic infections (infections that take advantage of weakness in the immune defences).

Experts agreed on the term AIDS in the early 1980s, before the discovery of HIV, to describe the then-new syndrome of profound immune suppression. Today, AIDS is understood as the latter stage along a continuum of HIV infection and disease.

If left untreated, HIV will almost always deplete the immune system, leaving the body vulnerable to one or more life-threatening diseases that normally do not affect healthy people.

Without treatment, HIV generally takes 8 to 10 years to progress to AIDS. A few weeks or months after infection a person may experience a 'flu-like illness' (seroconversion illness) and then feel well again. The interval between initial infection and the appearance of symptoms indicating advanced HIV-related disease (AIDS) varies, however, and appears to be shorter for persons infected through blood transfusion and for children.

I hear that HIV is not visible and that you cannot feel it either. So how can I tell if I have HIV, or if someone else has it?

It is impossible to tell if someone has the virus just by looking at or talking to the person. The only way for someone to know his or her status is by getting tested 3-6 months after any possible exposure. Even if the test result is negative, if there has been a recent exposure it should be repeated 3 months later. Today, because tests are more precise it is possible for some tests to detect the antibodies earlier on. It is important to get tested for your own well-being and the well-being of others, as well as to know the ways to prevent infection and to encourage others to do the same.

How do I know if I have HIV?

The only way to know if you are living with HIV is by getting tested. Antibodies to HIV can be detected through a simple test that is available in most places all over the world. UN Cares Minimum Standard number 5 specifies that such a test should be available to you, as a UN employee, and to your family.

More Information

For detailed information about HIV and AIDS here are sites that we recommend:

  • 25 years of AIDS factsheet
    This year will mark 25 years since scientists in the United States reported the first clinical evidence of a disease that would later become known as acquired immunodeficiency syndrome or AIDS. A factsheet on the history of the epidemic can now be found on the UNAIDS website.
  • The HIV Life Cycle 
    A comprehensive description of the HIV Life cycle, by AIDSMEDS.org
  • Stages of HIV infection 
    A description by AVERT.org, a UK based charity