The routes of HIV transmission are well documented by scientists, but health officials continually grapple with the publicís unfounded fears concerning the potential for HIV transmission by other means. HIV differs from other infectious viruses in that it dies quickly if exposed to the environment. No evidence has linked HIV transmission to casual contact with an infected person, such as a handshake, hugging, or kissing, or even sharing dishes or bathroom facilities. Studies have been unable to identify HIV transmission from modes common to other infectious diseases, such as an insect bite or inhaling virus-infected droplets from an infected personís sneeze or cough.
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, some widely dispersed information does not reflect the conclusions of scientific findings. The Centers for Disease Control and Prevention (CDC) provides the following information to help correct a few commonly held misperceptions about HIV.
HIV is spread by sexual contact with an infected person, by needle-sharing among injecting drug users, or, less commonly (and now very rarely in countries where blood is screened for HIV antibodies), 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 the worker's bloodstream through an open cut or splashes into a mucous membrane (e.g., eyes or inside of the nose). There has been only one demonstrated instance of patients being infected by a health-care worker; this involved HIV transmission from an infected dentist to six patients. Investigations have been completed involving more than 22,000 patients of 63 HIV-infected doctors and dentists, and no other cases of this type of transmission have been identified.
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 (for example, through air or insects), the pattern of reported AIDS cases would be much different from what has been observed, and cases would be occurring much more frequently in persons who report no identified risk for infection. All reported cases suggesting new or potentially unknown routes of transmission are promptly and thoroughly 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 specifically address some of the more common misperceptions about HIV transmission.
HIV in the Environment
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: Saliva, Tears, and Sweat). In order to obtain data on the survival of HIV, laboratory studies have required the use of artificially high concentrations of laboratory-grown virus. Although these unnatural concentrations of HIV can be kept alive under precisely controlled and limited laboratory conditions, CDC studies have shown that drying of even these high concentrations of HIV reduces the number of infectious viruses 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 alarmed people unnecessarily. Results from laboratory studies should not be used to determine specific personal risk of infection because 1) the amount of virus studied is not found in human specimens or anyplace else in nature, and 2) no one has been identified as infected with HIV due to contact with an environmental surface. Additionally, since 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, it does not spread or maintain infectiousness outside its host.
Households and Other Settings
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 or body fluids. To prevent even such rare occurrences, precautions, as described in previously published guidelines, should be taken in all settings -- including the home -- to prevent exposures to the blood or body fluids 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 body fluids that could possibly contain blood, such as urine, feces, or vomit. Cuts, sores, or breaks on both the caregiver'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 appropriately.
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 out of the reach of children and visitors.)
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 unless they have other infections or illnesses (such as diarrhea or hepatitis A) for which any food service worker, regardless of HIV infection status, should be restricted. The Public Health Service 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 (e.g., hairdressers, barbers, cosmetologists, 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 (e.g., tattooing and acupuncture needles, ear piercing devices) should be used once and disposed of or thoroughly cleaned and sterilized after each use using procedures recommended for use in health-care institutions. Instruments not intended to penetrate the skin but which may become contaminated with blood (e.g., razors) should be used for only one client and disposed of or thoroughly cleaned and disinfected after each use.