Frequently Asked Questions about AIDS/HIV
HIV (human immunodeficiency virus) is the name of the virus that causes AIDS. Scientists have identified the virus as a "retrovirus," which is a virus in a very specific family of viruses. This virus is passed from one person to another through blood-to-blood and sexual contact. In addition, infected pregnant women can pass HIV to their babies during pregnancy, delivery, or breast-feeding. People with HIV have what is called HIV infection. Most of these people will develop AIDS as a result of their HIV infection.
These body fluids have been proven to spread HIV:
A recent study has found the strongest evidence to date that HIV-1 probably originated in chimpanzees. The study found a retrovirus in one species of chimpanzee that is related to the HIV-1 virus that affects humans. The finding of HIV-1 in humans is likely to have resulted from cross-species transmission, but it is not known how this transmission occurred.
Two types of HIV have been identified to date. HIV-1 is the main HIV type in the United States and throughout the world. HIV-2 is primarily found in West Africa and other parts of Africa. Few cases have been found in the U.S. The origin of HIV-2 has been identified as being from a different primate species than HIV-1.
The only way to determine for sure whether you are infected is to be tested for HIV. You cannot rely on symptoms to know whether or not you are infected. Many people who are HIV positive do not have any symptoms for many years.
The following may be warning signs of infection with HIV:
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 or not you are infected is to be tested for HIV infection.
AIDS stands for acquired immunodeficiency syndrome. A person first becomes HIV infected and later, in most cases, develops AIDS. HIV can weaken the immune system to the point that it has difficulty fighting off "opportunistic" infections (infections that are usually controlled by a healthy immune system).
A person receives an AIDS diagnosis from a doctor after developing one or more specific opportunistic infections, also known as AIDS indicator illnesses. There are several illnesses including severe pneumonia, several forms of cancer, damage to the brain and nervous system, and extreme weight loss. An HIV-positive person who has not had any serious illnesses also can receive an AIDS diagnosis if blood tests indicate the person's T-cell count is 200 or below.
In 1982, the Centers for Disease Control and Prevention (CDC) officially adopted the name, acquired immunodeficiency syndrome (AIDS), after meeting with groups composed of persons with hemophilia; blood industry officials; gay community organizations; and assorted leaders from CDC, the National Institutes of Health, and the Food and Drug Administration.
The scientific evidence is overwhelming and compelling that HIV is the cause of AIDS. In addition, it is not known why some people exposed to HIV become infected while others do not, but this is likely related to the amount of virus they were exposed to, as well as to the route of entry (e.g., about 95% of persons given a transfusion with HIV-infected blood have developed the virus).
Before the discovery of HIV, evidence from studies involving the tracing of patients' sex partners, as well as cases occurring in blood recipients had clearly indicated that the underlying cause of the condition was an infectious agent. Since then, studies have found that infection with HIV has been the sole common factor throughout the world shared by those with AIDS, including: homosexual men; transfusion recipients; persons with hemophilia; sex partners of infected persons; children born to infected women; and occupationally exposed health care workers.
This time varies greatly from person to person and can depend on many factors, including a person's health status and their health-related behaviors.
Today, medical treatments are available that can slow the rate at which HIV weakens the immune system. Other treatments can prevent or cure some of the illnesses associated with AIDS. However, the treatments do not cure AIDS itself. As with other diseases, early detection offers more options for treatment and preventive health care.
It is possible to be infected with HIV without showing any symptoms. However, an individual can transmit the virus to others, even if he or she has no symptoms. In the United States, an estimated 800,000 to 900,000 people are infected with HIV, and approximately 250,000 of those individuals do not know it.
Many people do not develop any symptoms when they first become infected with HIV. Some people, however, have a flu-like illness within a month or two after exposure to the virus. They may have fever, headache, malaise, and enlarged, easily-felt lymph nodes in the neck and groin. These symptoms usually disappear within a week to a month and are often mistaken for those of another viral infection.
More persistent or severe symptoms may not surface for a decade or more after HIV first enters the body in adults, but may surface within two years in children born with HIV infection. This period of "asymptomatic" infection is variable and some people may begin to have persistent or severe symptoms within a few months. During the asymptomatic period, HIV is actively infecting and killing cells of the immune system.
The "window period" (also called seroconversion or antibody development periods) is the time between when a person is exposed to HIV and their body develops antibodies that indicate that a person has become infected with HIV. According to the Centers for Disease Control and Prevention (CDC), most people with HIV develop antibodies against the virus within three months after infection. CDC studies indicate that it is highly unlikely that it would take longer than six months for HIV antibodies to be detectable during tests.
The period between infection with HIV and development of AIDS is long and usually varies. During the incubation (asymptomatic) period, a person is infected with HIV but does not seem ill.
Signs and symptoms that HIV-infected persons first may show include swollen lymph glands, tiredness, weight loss, fever, loss of appetite, diarrhea, night sweats, and yeast infections.
When HIV enters the body, it primarily infects T4 cells (also called CD cells). HIV not only reduces the number of T4 cells, it can also impair a T4 cell's functioning. HIV-infected individuals with very low T4 cell counts tend to have more serious infections. Therefore, regular tests to determine T-cell counts can be an important element in monitoring the health of an HIV-infected person. These counts are also used to determine when certain treatments are needed.
Over time, HIV weakens the body's immune system and thus makes it more and more vulnerable to other viruses and infections including: certain pneumonias; several forms of cancer; damage to the brain and nervous system; and extreme weight loss. These conditions can signal the onset of AIDS. However, with medical treatment, HIV infection can usually be slowed and the onset of AIDS delayed.
Why a small minority of HIV-infected people have remained healthy for many years without loss of immune function remains unknown. However, research has found that those with HIV disease that has not progressed had very low levels of HIV in their blood and lymph nodes.
There have been no documented instances of HIV being transmitted through the environment. Normally, in laboratory studies, HIV must be grown in much higher concentrations (up to 100,000 times greater) than those found in the human body. The virus lives well under specific laboratory conditions, and in blood and certain body fluids. However, the virus does not live on surfaces outside the body unless there is fresh blood or certain body fluids present.
Studies on the survival of HIV after it has "dried" indicate that drying causes a rapid reduction in virus concentration, rendering 90 to 99 percent of the virus inactive within one to two hours. The overwhelming scientific evidence is that HIV is fragile and highly susceptible to physical and chemical agents, including heat, and therefore does not survive well outside the human body.
These observations, coupled with the enormous dilution factors in sewage systems, suggest that on-the-job HIV risk factors for sewage workers are virtually nonexistent. Because there is no evidence that HIV can be transmitted by the fecal-oral route or by air, fears associated with HIV transmission by other types of contact with sewage are not warranted.
Although there have been no specific studies of HIV survival in corpses before or after embalming, no instances of HIV transmission have been reported from an exposure incurred in performing mortuary services. The chemical germicides in embalming fluids have been tested and found to completely inactivate HIV. The Centers for Disease Control and Prevention has published occupational infection control guidelines that apply to mortuary workers, including embalmers.