HIV (human immunodeficiency virus) is the virus that causes AIDS. This virus may be passed from one person to another when infected blood, semen, or vaginal secretions come in contact with an uninfected person’s broken skin or mucous membranes*. In addition, infected pregnant women can pass HIV to their baby during pregnancy or delivery, as well as through breast-feeding. People with HIV have what is called HIV infection. Some of these people will develop AIDS as a result of their HIV infection.
* A mucous membrane is wet, thin tissue found in certain openings to the human body. These can include the mouth, eyes, nose, vagina, rectum, and opening of the penis.
The earliest known case of HIV-1 in a human was from a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of 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 carinii 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.
AIDS stands for acquired immunodeficiency syndrome. - An HIV-infected person receives a diagnosis of AIDS, after developing, - - - one of the CDC-defined AIDS indicator illnesses. An HIV-positive person who has not had any serious illnesses also can receive an AIDS diagnosis on the basis of certain blood tests. (CD4+ counts).
A positive HIV test result does not mean that a person has AIDS. A diagnosis of AIDS is made by a physician using certain clinical criteria (e.g., AIDS indicator illnesses).
Infection with HIV can weaken the immune system to the point that it has difficulty fighting off certain infections. - - - - - - - These types of infections are known as "opportunistic" infections because they take the opportunity a weakened immune system gives to cause illness.
Many of the infections that cause problems or may be life-threatening for people with AIDS are usually controlled by a healthy immune system. The immune system of a person with AIDS is weakened to the point that medical intervention may be necessary to prevent or treat serious illness.
- - - Today there are medical treatments that can slow down the rate at which HIV weakens the immune system. There are other treatments that can prevent or cure some of the illnesses associated with AIDS. As with other diseases, early detection offers more options for treatment and preventative care.
- - - Research has revealed a great deal of valuable medical, scientific, and public health information about the human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). - - The ways in which HIV can be transmitted have been clearly identified. Unfortunately, false information or statements that are not supported by scientific findings continue to be shared widely through the Internet or popular press.
- - -Research has revealed a great deal of valuable medical, scientific, and public health information about the human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). - The ways in which HIV can be transmitted have been clearly identified. - - Unfortunately, false information or statements that are not supported by scientific findings continue to be shared widely through the Internet or popular press.
Therefore, The Centers for Disease Control and Prevention (CDC) has prepared this fact sheet to correct a few misperceptions about HIV.
HIV is spread by sexual contact with an infected person, by sharing needles and/or syringes (primarily for drug injection) with someone who is infected, or, less com-monly (and now very rarely in countries where blood is screened for HIV antibod-dies), through transfusions of infected blood or blood clotting factors. Babies born to HIV-infected women may become infected before or during birth or through breast-feeding after birth.
In the health care setting, workers have been infected with HIV after being stuck with needles containing HIV-infected blood or, less frequently, after infected blood gets into a worker's open cut or a mucous membrane (for example, the eyes or inside of the nose). There has been only one instance of patients being infected by a health care worker in the United States; this involved HIV transmission from one infected dentist to six patients. Investigations have been completed involving more than 22,000 patients of 63 HIV-infected physicians, surgeons, and dentists, and no other cases of this type of transmission have been identified in the United States.
Some people fear that HIV might be transmitted in other ways; - - - however, no scientific evidence to support any of these fears has been found. If HIV were being transmitted through other routes (such as through air, water, or insects), - - - - the pattern of reported Auto-Immune Disease Cases would be much different from what has been observed. For example, if mosquitoes could transmit HIV infection, many more young children and preadolescents would have been diagnosed with AIDS.
All reported cases suggesting new or potentially unknown routes of transmission are thoroughlfluid y investigated by state and local health departments, - - - - with the assistance, guidance, and laboratory support from CDC. No additional routes of transmission have been recorded, despite a national sentinel system designed to detect just such an occurrence.
The following paragraphs address some of the common misperceptions about HIV transmission.
These body fluids have been proven to spread HIV:
* Blood * Breast Milk
* Semen * Other body fluids containing blood
* Vaginal Fluid
There are additional body fluid that may transmit the virus that health care workers may come in contact with:
* fluid surrounding the brain and the spinal cord
* fluid surrounding bone joints
* fluid surrounding an unborn baby
- - - - -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.
As with other diseases, early detection of infection allows for more options for treatment and preventative health care.
- Scientists and medical authorities agree that HIV does not survive well in the environment, making the possibility of environmental transmission remote. HIV is found in varying concentrations or amounts in blood, semen, vaginal fluid, breast milk, saliva, and tears. (See page 3, Saliva, Tears, and Sweat.) To obtain data on the survival of HIV, laboratory studies have required the use of data artificially high concentrations of laboratory-grown virus.
- Although these unnatural concentrations of HIV can be kept alive for days or even weeks under precisely controlled and limited laboratory conditions, CDC studies have shown that drying of even these high concentrations of HIV reduces the amount of infectious virus by 90 to 99 percent within several hours. - - Since the HIV concentrations used in laboratory studies are much higher than those actually found in blood or other specimens, drying of HIV-infected human blood or other body fluids reduces the theoretical risk of environmental transmission to that which has been observed--essentially zero. - - - - Incorrect interpretation of conclusions drawn from laboratory studies have unnecessarily alarmed some people.
Results from laboratory studies should not be used to assess specific personal risk of infection because (1) the amount of virus studied is not found in human specimens or elsewhere in nature, - - - - and (2) no one has been identified as infected with HIV due to contact with an environmental surface.
Additionally, HIV is unable to reproduce outside its living host (unlike many bacteria or fungi, which may do so under suitable conditions), except under laboratory conditions, therefore, it does not spread or maintain infectiousness outside its host.
- - Although HIV has been transmitted between family members in a household setting, this type of transmission is very rare. These transmissions are believed to have resulted from contact between skin or mucous membranes and infected blood. - - -To prevent even such rare occurrences, precautions, as described in previously published guidelines, should be taken in all setting "including the home" to prevent exposures to the blood of persons who are HIV infected, at risk for HIV infection, or whose infection and risk status are unknown. For example:
|Gloves should be worn during contact with blood or other bodily fluids that could possibly obtain visible blood such as, urine, feces vomit. |
|Cuts, sores, or breaks on both the care giver's and patient's exposed skin should be covered with bandages. |
|Hands and other parts of the body should be washed immediately after contact with blood or other body fluids, and surfaces soiled with blood should be disinfected properly. |
|Practices that increase the likelihood of blood contact, such as sharing of razors and toothbrushes should be avoided . |
|Needles and other sharp instruments should be used only when medically necessary and handled according to recommendations for health-care settings. |
| Do not put caps back on needles by hand or remove needles from syringes. Dispose of needles in puncture-proof containers. |
Casual contact through closed-mouth kissing is not a risk for transmission of HIV. Because of the potential for contact with blood during "French" or open-mouth kissing. CDC recommends against engaging in this activity with a person known to be infected. However, the risk of acquiring HIV during open-mouth kissing is believed to be very low. CDC has investigated only one case of HIV infection that may be attributed to contact with blood during open-mouth kissing.
In 1997, CDC published findings from a state health department investigation of an incident that suggested blood-to-blood transmission of HIV by a human bite. There have been other reports in the medical literature in which HIV appeared to have been transmitted by a bite. Severe trauma with extensive tissue tearing and damage and presence of blood were reported in each of these instances. Biting is not a common way of transmitting HIV. - - - In fact, there are numerous reports of bites that did not result in HIV infection.
**HIV has been found in saliva and tears in very low quantities from some AIDS patients. - - It is important to understand that finding a small amount of HIV in a body fluid does not necessarily mean that HIV can be transmitted by that body fluid. - - - HIV has not been recovered from the sweat of HIV-infected persons. - - - - - - - Contact with saliva, tears, or sweat has never been shown to result in transmission HIV.
From the onset of the HIV epidemic, there has been concern about transmission of the virus by biting and bloodsucking insects. However, studies conducted by researchers at CDC and elsewhere have shown no evidence of HIV transmission through insects------even in areas where there are many cases of AIDS and large populations of insects such as mosquitoes. - - - Lack of such outbreaks, despite intense efforts to detect them, supports the conclusion that HIV is not transmitted by insects.
The results of experiments and observations of insect biting behavior indicate that when an insect bites a person, - it does not inject its own or a previously bitten person's or animal's blood into the next person bitten. Rather, it injects saliva, - - - - - which acts as a lubricant or anticoagulant so the insect can feed efficiently. Such diseases as yellow fever and malaria are transmitted through the saliva of specific species of mosquitoes. However, HIV lives for only a short time inside an insect and, unlike organisms that are transmitted via insect bites, HIV does not reproduce (and does not survive) in insects. Thus, even if the virus enters a mosquito or another sucking or biting insect, - - -- -the insect does not become infected and cannot transmit HIV to the next human it feeds on or bites. HIV is not found in insect feces.
There is also no reason to fear that a biting or bloodsucking insect, - -such as a mosquito, could transmit HIV from one person to another through HIV-infected blood left on its mouth parts. Two factors serve to explain why this is so--first, infected people do not have constant, high levels of HIV in their bloodstreams and, second, insect mouth parts do not retain large amounts of blood on their surfaces. - - - -Further, scientists who study insects have determined that biting insects normally do not travel from one person to the next immediately after ingesting blood. - - Rather, they fly to a resting place to digest this blood meal.
There is no known risk of HIV transmission to co-workers, clients, or consumers from contact in industries such as food-service establishments (see information on survival of HIV in the environment). - - - Food service workers known to be infected with HIV need not be restricted from work - - - less they have other infections or illnesses (such as diarrhea or hepatitis A)- which any food-service worker, regardless of HIV infection status, should be restricted.
CDC recommends that all food-service workers follow recommended standards and practices of good personal hygiene and food sanitation.
In 1985, CDC issued routine precautions that all personal-service workers (such as hairdressers, barbers, cosmetologists, and massage therapists) should follow, even though, - - there is no evidence of transmission from a personal-service worker to a client or vice versa. Instruments that are intended to penetrate the skin (such as tattooing and acupuncture needles, ear piercing devices) should be used once and disposed of or thoroughly cleaned and sterilized.
- - - - - - - -Instruments not intended to penetrate the skin but which may become contaminated with blood (for example, razors) should be used - - - for only one client and disposed of, - - - or thoroughly cleaned and disinfected after each use. Personal-service workers can use the same cleaning procedures that are recom-mended for health care institutions.
Center For Disease Control knows of no instances of HIV transmission through tattooing or body piercing, - - - although Hepatitis B virus has been transmitted during some of these practices. One case of HIV transmission from acupuncture has been documented. Body piercing (other than ear piercing) is relatively new in the United States, and the medical complications for body piercing appear to be greater than for tattoos. Healing of piercings generally will take weeks, and sometimes even months, and the pierced tissue could conceivably be abraded (torn or cut) or inflamed even after healing.
- - - Therefore, a theoretical HIV transmission risk does exist if the unhealed or abraded tissues come into contact with an infected person's blood, - - - or other infectious body fluid. - - - - - Additionally, HIV could be transmitted if instruments contaminated with blood are not sterilized or disinfected between clients.
There is a theoretical risk of HIV infection from any behavior that study has failed to show resulted in HIV infection, - - but in which a body fluid which is known to contain HIV comes in contact with a partner's mucous membranes or blood. There is a known risk of infection wherever a behavior has been documented to result in HIV transmission by case series or prospective, epidemiological study.
There is a low risk of infection when prospective, cohort-style studies have failed to demonstrate a statistically significant relationship - - - between the behavior and infection, but case reports continue to suggest a correlation. - -There is a high risk of infection when prospective cohort-style study has established a relationship and the risk is deemed substantial by the Subcommittee.
Condoms are classified as medical devices and are regulated by the Food and Drug Administration (FDA). Condom manufacturers in the United States test each latex condom for defects, including holes, before it is packaged. The proper and consistent use of latex or polyurethane (a type of plastic) condoms when engaging in sexual intercourse--vaginal, anal, or oral--can greatly reduce a person's risk of acquiring or transmitting sexually transmitted diseases, including HIV infection.
There are many different types and brands of condoms available--however, only latex or polyurethane condoms provide a highly effective mechanical barrier to HIV. In laboratories, viruses occasionally have been shown to pass through natural membrane ("skin" or lambskin) condoms, which may contain natural pores and are therefore not recommended for disease prevention (they are documented to be effective for contraception). Women may wish to consider using the female condom when a male condom cannot be used.
For condoms to provide maximum protection, they must be used consistently (every time) and correctly. Several studies of correct and consistent condom use clearly show that latex condom breakage rates in this country are less than 2 percent. Even when condoms do break, one study showed that more than half of such breaks occurred prior to ejaculation.
When condoms are used reliably, they have been shown to prevent pregnancy up to 98 percent of the time among couples using them as their only method of contraception. Similarly, numerous studies among sexually active people have demonstrated that a properly used latex condom provides a high degree of protection against a variety of sexually transmitted diseases, including HIV infection.
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--homosexuality, drug use, poverty--related to this disease. Although the scientific evidence is overwhelming and compelling that HIV is the cause of AIDS, the disease process is not yet 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 homosexual men, transfusion recipients, persons with hemophilia, sex partners of infected persons, children born to infected women, and occupationally exposed health care workers. Recommendations to prevent HIV involve guidance to avoid or modify behaviors that pose a risk of transmitting the virus as well as the use of tests to screen donors of blood and organs.
The inescapable conclusion of more than 15 years of scientific research is that people, if exposed to HIV through sexual contact or injecting drug use, - - may become infected with HIV. If they become infected, most will eventually develop AIDS.
CDC is committed to providing the scientific community and the public with accurate and objective information about HIV infection and AIDS. It is vital that clear information on HIV infection and AIDS be readily available to help prevent further transmission of the virus and to allay fears and prejudices caused by misinformation. For a complete description of CDC's HIV/AIDS prevention programs, see "Facts about CDC's Role in HIV and AIDS Prevention."
Reference: Adapted From Centers For Disease Control Fact Sheets
Atlanta, Georgia 30309
Compiled By: Deborah Shrira, RPH , CMA
Udpated 15 February 2006