HIV stands for Human Immunodeficiency Virus. It is the virus that causes AIDS. AIDS stands for Acquired Immune Deficiency Syndrome. HIV can be transmitted through the blood, sexual fluids, or breast milk of an HIV-infected person.
Over time, infection with HIV can weaken the immune system to the point that the system has difficulty fighting off certain infections. These types of infections are known as opportunistic infections. These infections are usually controlled by a healthy immune system, but they can cause problems or even be life-threatening in someone with AIDS.
A blood test can determine if a person is infected with HIV, but if a person tests positive for HIV, it does not necessarily mean that the person has AIDS. A diagnosis of AIDS is made by a physician according to the CDC AIDS Case Definition. A person infected with HIV may receive an AIDS diagnosis after developing one of the CDC-defined AIDS indicator illnesses. A person with HIV can also receive an AIDS diagnosis on the basis of certain blood tests (CD4 counts) and may not have experienced any serious illnesses.
There are many theories about the origin of HIV. The first known case was found in a blood sample collected from man from Kinshasha, Democratic Republic of Congo in 1959. Genetic analysis of this blood suggests that the origin of HIV came from a single strain of HIV-1 in the 1940s or 1950s. In the U.S. the virus is known to have existed since the mid 1970s. Symptoms of rare types of what are now known as opportunistic infections began manifesting themselves between 1979-1981. HIV was first isolated by scientists in 1983. The virus was at first called HTLV-III/LAV (human T-cell lymphotropic virus-type III/lymphadenopathy- associated virus) by an international scientific committee. This name was later changed to HIV (human immunodeficiency virus).
AIDS is a disease caused by HIV. HIV infects cells of the human immune system and destroys or impairs their function. Infection with this virus leads to slow destruction of a persons’ immune system making them more susceptible to many kinds of infections. Once a person with HIV develops any one of a number of rare infections or cancers - tuberculosis, pneumonia, candidiases or tumors – they are said to have AIDS. This most often occurs 10-15 years after a person becomes infected with HIV.
According to the Centers for Disease Control and Prevention (CDC), prior to 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.
Since 1996, the introduction of powerful anti-retroviral therapies has dramatically changed the progression time between HIV infection and the development of AIDS. There are also other medical treatments that can prevent or cure some of the illnesses associated with AIDS, though the treatments do not cure AIDS itself. Because of these advances in drug therapies and other medical treatments, estimates of how many people will develop AIDS and how soon are being recalculated, revised, or are currently under study.
According to the Centers for Disease Control and Prevention (CDC), approximately 1 million persons in the United States are living with diagnosed or undiagnosed HIV/AIDS. CDC estimates there are over 41,000 new HIV infections in the United States each year.
The Joint United Nations Programme on HIV/AIDS (UNAIDS) estimates that, since the beginning of the epidemic, almost 60 million people worldwide have been infected with HIV and 25 million people have died of HIV-related causes. UNAIDS estimates that about 33.4 million people worldwide were living with HIV in 2008.
There are various risk factors that make some people more at risk for contracting HIV than others. Most people, however, run some risk of contracting HIV as they share in one or more of the following risk factors: