Measles: Questions and Answers
Information about the disease and vaccines
HIV is the human immunodeficiency virus. It is the virus that can lead to acquired immune deficiency syndrome, or AIDS. The Center for Disease Control (CDC) estimates that about 56,000 people in the United States contracted HIV in 2006.
HIV damages a person’s body by destroying specific blood cells, called CD4+ T cells, which are crucial to helping the body fight diseases.
HIV is spread primarily by:
The earliest known case of infection with HIV-1 in a human was detected in a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of the Congo. (How he became infected is not known.) Genetic analysis of this blood sample suggested that HIV-1 may have stemmed from a single virus in the late 1940s or early 1950s.
We know that the virus has existed in the United States since at least the mid- to late 1970s. From 1979–1981 rare types of pneumonia, cancer, and other illnesses were being reported by doctors in Los Angeles and New York among a number of male patients who had sex with other men. These were conditions not usually found in people with healthy immune systems.
In 1982 public health officials began to use the term "acquired immunodeficiency syndrome," or AIDS, to describe the occurrences of opportunistic infections, Kaposi's sarcoma (a kind of cancer), and Pneumocystis jirovecii pneumonia in previously healthy people. Formal tracking (surveillance) of AIDS cases began that year in the United States.
In 1983, scientists discovered the virus that causes AIDS. The virus was at first named 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).
For many years scientists theorized as to the origins of HIV and how it appeared in the human population, most believing that HIV originated in other primates. Then in 1999, an international team of researchers reported that they had discovered the origins of HIV-1, the predominant strain of HIV in the developed world. A subspecies of chimpanzees native to west equatorial Africa had been identified as the original source of the virus. The researchers believe that HIV-1 was introduced into the human population when hunters became exposed to infected blood.
For more information on this discovery, visit the NIH National Institute of Allergy and Infectious Diseases press release. For information on the theory that HIV originated in polio vaccines, visit the CDC Vaccine Safety site.
AIDS stands for Acquired Immunodeficiency Syndrome.
Before the development of certain medications, people with HIV could progress to AIDS in just a few years. Currently, people can live much longer - even decades - with HIV before they develop AIDS. This is because of “highly active” combinations of medications that were introduced in the mid-1990s.
A diagnosis of AIDS is made by a physician using specific clinical or laboratory standards.
The epidemic of HIV and AIDS has attracted much attention both within and outside the medical and scientific communities. Much of this attention comes from the many social issues related to this disease such as sexuality, drug use, and poverty. Although the scientific evidence is overwhelming and compelling that HIV is the cause of AIDS, the disease process is still not completely understood. This incomplete understanding has led some persons to make statements that AIDS is not caused by an infectious agent or is caused by a virus that is not HIV. This is not only misleading, but may have dangerous consequences. Before the discovery of HIV, evidence from epidemiologic studies involving tracing of patients’ sex partners and cases occurring in persons receiving transfusions of blood or blood clotting products had clearly indicated that the underlying cause of the condition was an infectious agent. Infection with HIV has been the sole common factor shared by AIDS cases throughout the world among men who have sex with men, transfusion recipients, persons with hemophilia, sex partners of infected persons, children born to infected women, and occupationally exposed health care workers.
The conclusion after more than 28 years of scientific research is that people, if exposed to HIV through sexual contact or injecting drug use for example, may become infected with HIV. If they become infected, most will eventually develop AIDS.
For more information, visit the NIH National Institute of Allergy and Infectious Diseases Fact sheet "The Evidence That HIV Causes AIDS".
Was HIV created in a lab?
No. HIV is a virus that has evolved over time and though it became a global pandemic only recently in human history, its origins are much older and found in nature.
How can I tell if I'm infected with HIV?
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. Many people who are infected with HIV do not have any symptoms at all for 10 years or more.
The following may be warning signs of advanced HIV infection:
However, no one should assume they are infected if they have any of these symptoms. Each of these symptoms can be related to other illnesses. Again, the only way to determine whether you are infected is to be tested for HIV infection.
Go to DC TAKES ON HIV to find an HIV Testing site in the District of Columbia.