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Frequently Asked Questions (FAQs) About HIV and AIDS (FAQ Home)

Transmission

How is HIV passed from one person to another? Return to top

HIV transmission can occur when blood, semen (including pre-seminal fluid, or "pre-cum"), vaginal fluid, or breast milk from an infected person enters the body of an uninfected person.

HIV can enter the body through a vein (e.g., injection drug use), the anus or rectum, the vagina, the penis, the mouth, other mucous membranes (e.g., eyes or inside of the nose), or cuts and sores. Intact, healthy skin is an excellent barrier against HIV and other viruses and bacteria.

These are the most common ways that HIV is transmitted from one person to another:

  • by having sexual intercourse (anal, vaginal, or oral sex) with an HIV-infected person
  • by sharing needles or injection equipment with an injection drug user who is infected with HIV
  • from HIV-infected women to babies before or during birth, or through breast-feeding after birth
HIV also can be transmitted through transfusions of infected blood or blood clotting factors. However, since 1985, all donated blood in the United States has been tested for HIV. Therefore, the risk of infection through transfusion of blood or blood products is extremely low. The U.S. blood supply is considered to be among the safest in the world. (For more information, see "How safe is the blood supply in the United States?")

Some health-care workers have become infected after being stuck with needles containing HIV-infected blood or, less frequently, after infected blood contact with the worker's open cut or through splashes into the worker's eyes or inside their nose. There has been only one instance of patients being infected by an HIV-infected health care worker. This involved HIV transmission from an infected dentist to six patients. (For more information, see "Are health care workers at risk of getting HIV on the job?" and "Are patients in a dentist's or doctor's office at risk of getting HIV?")

What is the probability of transmission from one HIV exposure? Return to top

HIV can be transmitted efficiently through blood transfusions: an estimated 95% of recipients become infected from transfusion of a single unit of infected whole blood. The per-contact probability of transmission from an HIV-infected source is much lower for injecting-drug-use and sexual exposures.

The risk for HIV transmission per episode of intravenous needle or syringe exposure is estimated at 0.67%.

Prospective surveillance studies indicate that the risk per episode of percutaneous exposure (e.g., a needlestick) to HIV-infected blood is estimated at 0.4% (upper limit of 95% confidence interval [Cl]=0.8%). The level of risk associated with the exposure of nonintact skin or mucous membranes to HIV-infected blood is far less than that associated with needlestick exposures.

The risk for HIV transmission per episode of receptive penile-anal sexual exposure is estimated at 0.1%-3%; the risk per episode of receptive vaginal exposure is estimated at 0.1%-0.2%. No published estimates of the risk for transmission from receptive oral exposure exist, but instances of transmission have been reported.

For more information refer to the September 25, 1998 Morbidity and Mortality Weekly Report, Management of Possible Sexual, Injecting-Drug-Use, or Other Nonoccupational Exposure to HIV, Including Considerations Related to Antiretroviral Therapy (Vol. 47: RR-17: page 3).

Can HIV be transmitted from other animals to humans? Return to top

No. HIV is a uniquely human disease. The chimpanzee is the only animal that has developed antibody to HIV. There are other retroviruses (HIV is but one in this family) that infect animals, such as monkeys, sheep, horses, goats, including feline leukemia virus and feline immunodeficiency virus found in cats. However, all of these animal retroviruses are specific to their hosts and have not been shown to be transmitted to humans. Similarly, HIV cannot be transmitted from a person with HIV to any of these animals.

Can I get infected with HIV from mosquitoes? Return to top

No. 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 previous victim's blood into the new victim. Rather, it injects saliva. 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, therefore, cannot 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.

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 combine to make infection by this route extremely unlikely--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.

Can HIV be transmitted by breast milk? Return to top

Yes. An HIV-infected woman can transmit the infection to her child during pregnancy, during labor and delivery, and through breastfeeding. HIV-infected women who breastfeed have been shown to increase their chances of transmitting HIV to their infants by 14% over the risk incurred during pregnancy, labor, and delivery. Because of the uncertainties surrounding timing of perinatal HIV transmission, CDC does not conduct surveillance for cases of HIV infection acquired through breastfeeding.

HIV-infected women in the United States are advised to avoid breastfeeding their infants because of the availability of safe and appropriate alternatives. Most cases of HIV infection resulting from breastfeeding occur in women who are unaware of their infection status. One recent study in two U.S. sites estimated that at least 3% of HIV-infected women giving birth breastfed their infants. The majority of these women were unaware of their infection at the time of delivery.

The U.S. Public Health Service has recommended universal HIV counseling and voluntary testing for pregnant women to enable women the opportunity to learn of their infection status for their own health and for preventing transmission to their infants.

Although universal precautions do not apply to human breast milk or saliva, some precautions against exposure to these fluids may be necessary. Because breast feeding has been implicated in the transmission of HIV infection from mother to infant, the use of gloves should be considered in situations such as milk banks, where exposure to human breast milk is extensive. Gloves do not need to be worn when feeding a child with breast or bottled milk.

Can HIV be transmitted by Immune Globulins? Return to top

One example of immune globulin is IG, a passive vaccination for hepatitis A. Since IG is a pooled plasma product, there was concern before 1985 that some donors to the pool might be infected with HIV. Since then, all blood and plasma donations in the United States are screened for antibody to HIV, and all positive units are discarded.

In addition, the IG is extracted using the Cohn cold fractionation method with ethanol, a process that would inactivated any HIV that could have entered the plasma pool.

Another example of an immune globulin is hepatitis B vaccine. Hepatitis B vaccine undergoes a unique three-step purification process that is known to inactivate viruses of all groups, including HIV, that cause in humans.

There is another immune globulin, known as RhoGam or Rho(D) immune globulin, which is given to women with Rh factor after delivery, abortion, and at other times to prevent Rh disease in future newborns. There is no evidence that Rh-IG presents a risk for transmission of HIV. Rh-IG is also produced by plasma fractionation methods which have been shown to effectively remove HIV by partitioning and inactivation. Indeed, because Rh-IG prevents the need for blood transfusions in some newborn babies, this product may prevent some potential exposures to HIV through blood transfusions.

No cases of AIDS or HIV infection have been attributed to the medical use of any immune globulin, and no scientific group has changed is recommendations regarding their use. Since there is documented benefit to using immune globulins, patients deserve the protection that immune globulins can provide.

Can HIV be transmitted by other body fluids? Return to top

HIV has been found in saliva and tears in only minute 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 of HIV.

Based on the available scientific evidence, the potential for HIV transmission via the communion cup or any other shared drinking vessel is extremely remote.

Although HIV has been transmitted in a few cases in the 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 settings --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, hands and other parts of the body should be washed immediately after contact with blood, and surfaces soiled with blood should be disinfected appropriately.

Can HIV be transmitted by wound to wound contact? Return to top

Transmission via wound-to-wound contact, although theoretically possible is highly unlikely given the improbability of such a scenario and the small concentration of virus that is likely to be present. If this type of casual contact did result in HIV transmission, the pattern of cases would be much higher than that shown in current reports. However, persons with open wounds who are likely to have occupational contact with blood and other potentially infectious body fluids, e.g. health-care workers, are urged to comply with universal precautions for the prevention of transmission of HIV and other bloodborne pathogens.

Evidence also indicates that bloodborne and sexually transmitted pathogens such as HIV are not transmitted during the preparation or serving of food or beverages, and no instances of HIV transmission have been documented in this setting. If such transmission readily occurred, we would expect to see an increase in the proportion of AIDS cases outside of recognized high-risk groups; no evidence of this has been found for any of the U.S. AIDS cases reported to the CDC. However, the Public Health Service recommends that all food service workers take care to avoid injury to their hands when preparing food. Should such an injury occur, food contaminated with blood should be discarded.

How safe is the blood supply in the United States? Return to top

The U.S. blood supply is among the safest in the world. Nearly all people infected with HIV through blood transfusions received those transfusions before 1985, the year HIV testing began for all donated blood.

The Public Health Service has recommended an approach to blood safety in the United States that includes stringent donor selection practices and the use of screening tests. U.S. blood donations have been screened for antibodies to HIV-1 since March 1985 and HIV-2 since June 1992. Blood and blood products that test positive for HIV are safely discarded and are not used for transfusions.

An estimated 1 in 450,000 to 1 in 660,000 donations per year are infectious for HIV but are not detected by current antibody screening tests. In August 1995, the FDA recommended that all donated blood and plasma also be screened for HIV-1 p24 antigen. The improvement of processing methods for blood products also has reduced the number of infections resulting from the use of these products. Currently, the risk of infection with HIV in the United States through receiving a blood transfusion or blood products is extremely low and has become progressively lower, even in geographic areas with high HIV prevalence rates.

Can I get HIV from casual contact (shaking hands, hugging, using a toilet, drinking from the same glass, or the sneezing and coughing of an infected person)? Return to top

No. HIV is not transmitted by day-to-day contact in the workplace, schools, or social settings. HIV is not transmitted through shaking hands, hugging, or a casual kiss. You cannot become infected from a toilet seat, a drinking fountain, a door knob, dishes, drinking glasses, food, or pets.

A small number of cases of transmission have been reported in which a person became infected with HIV as a result of contact with blood or other body secretions from an HIV-infected person in the household. Although contact with blood and other body substances can occur in households, transmission of HIV is rare in this setting. However, persons infected with HIV and persons providing home care for those who are HIV-infected should be fully educated and trained regarding appropriate infection-control techniques.

HIV is not an airborne or food-borne virus, and it does not live long outside the body. HIV can be found in the blood, semen, or vaginal fluid of an infected person. The three main ways HIV is transmitted are:

  • through having sex (anal, vaginal, or oral) with someone infected with HIV.
  • through sharing needles and syringes with someone who has HIV.
  • through exposure (in the case of infants) to HIV before or during birth, or through breast feeding.
For more information about HIV transmission, see "Facts about the Human Immunodeficiency Virus and Its Transmission."

Can I get HIV from kissing on the cheek? Return to top

HIV is not casually transmitted, so kissing on the cheek is very safe. Even if the other person has the virus, your unbroken skin is a good barrier. No one has become infected from such ordinary social contact as dry kisses, hugs, and handshakes.

Can I get HIV from open-mouth kissing? Return to top

Open-mouth kissing is considered a very low-risk activity for the transmission of HIV. However, prolonged open-mouth kissing could damage the mouth or lips and allow HIV to pass from an infected person to a partner and then enter the body through cuts or sores in the mouth. Because of this possible risk, the CDC recommends against open-mouth kissing with an infected partner.

One case suggests that a woman became infected with HIV from her sex partner through exposure to contaminated blood during open-mouth kissing. The July 11, 1997, Morbidity and Mortality Weekly Report contains an article on this case.

Can HIV be transmitted in swimming pool water? Return to top

HIV cannot be spread by sharing washing facilities or swimming in the same pool with an HIV-infected person. The body secretions which would normally be washed off in a swimming pool (e.g., sweat or saliva) are not body fluids that transmit HIV. Blood, semen, and vaginal secretions would only enter a swimming pool under exceptional circumstances. Any virus that did get into a swimming pool would be greatly diluted, making it non-infectious. Most swimming pools also contain disinfective agents, such as chlorine, that inactivate HIV.

Why is injecting drugs a risk for HIV? Return to top

At the start of every intravenous injection, blood is introduced into needles and syringes. HIV can be found in the blood of a person infected with the virus. The reuse of a blood-contaminated needle or syringe by another drug injector (sometimes called "direct syringe sharing") carries a high risk of HIV transmission because infected blood can be injected directly into the bloodstream.

In addition, sharing drug equipment (or "works") can be a risk for spreading HIV. Infected blood can be introduced into drug solutions by:

  • using blood-contaminated syringes to prepare drugs; reusing water;
  • reusing bottle caps, spoons, or other containers ("spoons" and "cookers") used to dissolve drugs in water and to heat drug solutions; or
  • reusing small pieces of cotton or cigarette filters ("cottons") used to filter out particles that could block the needle.
"Street sellers" of syringes may repackage used syringes and sell them as sterile syringes. For this reason, people who continue to inject drugs should obtain syringes from reliable sources of sterile syringes, such as pharmacies. It is important to know that sharing a needle or syringe for any use, including skin popping and injecting steroids, can put one at risk for HIV and other blood-borne infections.

Can HIV be transmitted by aerosol? Return to top

Issues regarding the possible transmission of bloodborne pathogens by aerosols are being examined on an ongoing basis by the AIDS in the Workplace Committee at CDC. At present time, there are no known instances in which bloodborne pathogens have been transmitted to patients or workers by respirable particles in a clinical setting. Studies in dental operatories and dialysis units have been unable to detect hepatitis B surface antigen (HbsAg) in air samples collected during treatment of patients whose blood was positive for HbsAg. The failure to detect HbsAg in air samples in these experiments suggests that detection of HIV would also be unusual, because the concentration of HbsAg in blood itself is higher than that of HIV.

Are health care workers at risk of getting HIV on the job? Return to top

As of December 1998, there have been 54 documented and 134 possible cases of occupational HIV transmission. Prospective surveillance studies indicate that the risk of seroconversion after a needlestick exposure to blood from an HIV-infected person is now approximately 0.3%. The level of risk associated with the exposure of nonintact skin or mucous membranes to HIV-infected blood is far less than that associated with needlestick exposures.

To assess potential risk factors for needlestick exposure, CDC, in collaboration with French and British public health authorities, conducted a retrospective case-control study using data reported to national surveillance systems in the United States, France, and the United Kingdom. The result of this study was reported in the December 22, 1995 Morbidity and Mortality Weekly Report.

The occupational risk of HIV infection should be recognized and managed appropriately by those who are routinely exposed to the blood of other persons. The risk can be minimized by adhering to the recommended infection-control guidelines and avoiding accidental injuries with needles and other sharp instruments.

Health-care workers concerned about needlestick exposures to HIV may want to contact the Hospital Infections Program, CDC, Atlanta, Georgia at 1-404-639-6425 or the National Clinicians' Post-Exposure Prophylaxis Hotline at 1-888-448-4911.

Are patients in a dentist's or doctor's office at risk of getting
HIV?
Return to top

Although HIV transmission is possible in health care settings, it is extremely rare. Medical experts emphasize that the careful practice of infection control procedures, including universal precautions, protects patients as well as health care providers from possible HIV infection in medical and dental offices.

In 1990, the CDC reported on an HIV-infected dentist in Florida who apparently infected some of his patients while doing dental work. Studies of viral DNA sequences linked the dentist to six of his patients who were also HIV-infected. The CDC has as yet been unable to establish how the transmission took place.

Further studies of more than 22,000 patients of 63 health care providers who were HIV-infected have found no further evidence of transmission from provider to patient in health care settings.

How did six patients of an HIV-infected dentist in Florida contract HIV? Return to top

There have been six cases in the practice of one HIV-infected dentist in Florida, where HIV transmission from a doctor to patient has been strongly suggested (Morbidity and Mortality Weekly Report, May 7, 1993.) Of the 10 HIV-infected patients identified in this Florida dental practice, six had no other documented source of infection and all six had HIV strains with DNA sequences that very closely resembled the dentist's strain. The remaining four infected patients had acknowledged behavioral risk factors and had HIV strains whose DNA sequences were not closely related to the strains infecting the dentist and the other patients.

During this investigation, the dental handpiece was considered as one of several possible mechanisms of transmission during invasive dental procedures. However, the evidence does not lead CDC to believe that the handpiece was a more likely mechanism of HIV transmission than other possibilities. These other possibilities include cuts or needlesticks to the dentist or the use of other instruments that may have been previously contaminated.

Investigators at CDC are not aware of any studies that confirm the transmission of bloodborne viruses such as hepatitis B virus (HBV) or HIV through the dental handpiece or other dental equipment. Although it may be theoretically possible for contaminated dental equipment or devices to pass a bloodborne virus from one patient to the next, no such cases of patient-to-patient transmission have been reported in a dental practice.

Neither the precise mechanism of transmission to these patients nor the reasons for transmission to multiple patients in a single practice are known. However, CDC is continuing to investigate all possible mechanisms of viral transmission. Factors that may be associated with transmission of bloodborne pathogens from infected health care workers to patients may reflect variations in the procedures performed and techniques used by the health care worker, infection control precautions used, and the concentration of the infecting agent.

CDC is not aware of any evidence to indicate that these transmissions of HIV were deliberate. Since the precise mechanism of transmission is still uncertain, the possibility that the dentist deliberately infected his patients will be considered as one of many possible routes.

For further information about the Florida dentist case, you may wish to refer to the following journal articles:

  • Ciesielski CA, Marianos DW, Schochetman G. The 1990 Florida dental investigation. Annals of Int Med 1994 Dec;121(11):886-8.

  • Ciesielski C, Marianos D, Chin-Yih O, et al. Transmission of human immunodeficiency virus in a dental practice. Annals of Int Med 1992 May 15;116(10):798-805.

Can HIV be transmitted between women during sex? Return to top

There have been several reports in the medical literature indicating possible female-to-female sexual transmission of HIV. AIDS surveillance data indicate that women with AIDS who are reported to have had sexual contact only with other women have also been reported to have injected drugs or to have received blood transfusions or blood components. Although these risk factors do not preclude the possibility that the mode of transmission of HIV for these women was female-to-female sexual contact, the absence of cases in lesbian women without other established risk factors is striking. We interpret this observation to mean that these women likely acquired their infection through injection drug use or receipt of blood transfusion or blood components.

Studies from HIV serosurveys among women attending sexually transmitted disease clinics and women's health clinics also suggest that HIV infection in lesbian and bisexual women is closely associated with injecting drug use or to sexual contact with men at increased risk for HIV infection. These data do not exclude the possibility of female-to-female sexual transmission of HIV, but they do indicate that it is rare. However rare such transmission may be, women who have sexual contact with other women need to be aware of the potential for infection with HIV, including the risk behaviors of their sex partners. Lesbian women should know that vaginal and cervical secretions and menstrual blood are potentially infectious and that mucous membrane (e.g., oral, vaginal) contact with infected blood or secretions can lead to HIV transmission.

Several recent articles concerning HIV and AIDS in women who have sex with women have been published. These include:

  • Chu SY, Conti L, Schable BA, Diaz T. Female-to-female sexual contact and HIV transmission. [letter] JAMA 1994;272:433.

  • Chu SY, Hammett TA, Buehler JW. Update: epidemiology of reported cases of AIDS in women who report sex only with other women, U.S. 1980-1991. AIDS 1992;6(5):518-19.

  • McCombs SB, McCray E, Wendell DA, Sweeney PA, Onorato IM. Epidemiology of HIV-1 infection in bisexual women. J Acquir Immune Defic Syndr 1992;5:850-2.
Can I get HIV from anal sex? Return to top

Yes, it is possible for either sex partner to become infected with HIV during anal sex. HIV can be found in the blood, semen, pre-seminal fluid, or vaginal fluid of a person infected with the virus. In general, the person receiving the semen is at greater risk of getting HIV because the lining of the rectum is thin and may allow the virus to enter the body during anal sex. However, a person who inserts his penis into an infected partner also is at risk because HIV can enter through the urethra (the opening at the tip of the penis) or through small cuts, abrasions, or open sores on the penis.

Having unprotected (without a condom) anal sex is considered to be a very risky behavior. If people choose to have anal sex, they should use a latex condom. Most of the time, condoms work well. However, condoms are more likely to break during anal sex than during vaginal sex. Thus, even with a condom, anal sex can be risky. A person should use a water-based lubricant in addition to the condom to reduce the chances of the condom breaking.

For more information on latex condoms, see "Facts about Condoms and Their Use in Preventing HIV Infection and Other STDs."

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

Can I get HIV from having vaginal sex? Return to top

Yes, it is possible to become infected with HIV through vaginal intercourse. In fact, it is the most common way the virus is transmitted in much of the world. HIV can be found in the blood, semen, pre-seminal fluid, or vaginal fluid of a person infected with the virus. The lining of the vagina can tear and possibly allow HIV to enter the body. Direct absorption of HIV through the mucous membranes that line the vagina also is a possibility.

The male may be at less risk for HIV transmission than the female through vaginal intercourse. However, HIV can enter the body of the male through his urethra (the opening at the tip of the penis) or through small cuts or open sores on the penis.

Risk for HIV infection increases if you or a partner has a sexually transmitted disease (STD). See also "Is there a connection between HIV and other sexually transmitted diseases?"

If you choose to have vaginal intercourse, use a latex condom to help protect both you and your partner from the risk of HIV and other STDs. Studies have shown that latex condoms are very effective, though not perfect, in preventing HIV transmission when used correctly and consistently. If either partner is allergic to latex, plastic (polyurethane) condoms for either the male or female can be used.

For more information on latex condoms, the female condom, and plastic (polyurethane) condoms, see "Facts about Condoms and Their Use in Preventing HIV Infection and Other STDs."

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

Can I get HIV from performing oral sex? Return to top

Yes, it is possible for you to become infected with HIV through performing oral sex. There have been a few cases of HIV transmission from performing oral sex on a person infected with HIV. While no one knows exactly what the degree of risk is, evidence suggests that the risk is less than that of unprotected anal or vaginal sex.

Blood, semen, pre-seminal fluid, and vaginal fluid all may contain the virus. Cells in the mucous lining of the mouth may carry HIV into the lymph nodes or the bloodstream. The risk increases

  • if you have cuts or sores around or in your mouth or throat;
  • if your partner ejaculates in your mouth; or
  • if your partner has another sexually transmitted disease (STD).
If you choose to have oral sex, and your partner is male,
  • use a latex condom on the penis; or
  • if you or your partner is allergic to latex, plastic (polyurethane) condoms can be used.
Research has shown the effectiveness of latex condoms used on the penis to prevent the transmission of HIV. Condoms are not risk-free, but they greatly reduce your risk of becoming HIV-infected if your partner has the virus.

If you choose to have oral sex, and your partner is female,

  • use a latex barrier (such as a dental dam or a cut-open condom that makes a square) between your mouth and the vagina. Plastic food wrap also can be used as a barrier.
The barrier reduces the risk of blood or vaginal fluids entering your mouth. For more information about latex condoms, female condoms, and plastic (polyurethane) condoms, see "Facts about Condoms and Their Use in Preventing HIV Infection and Other STDs."

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

Can I get HIV from someone performing oral sex on me? Return to top

Yes, it is possible for you to become infected with HIV through receiving oral sex. If your partner has HIV, blood from their mouth may enter the urethra (the opening at the tip of the penis), the vagina, the anus, or directly into the body through small cuts or open sores. While no one knows exactly what the degree of risk is, evidence suggests that the risk is less than that of unprotected anal or vaginal sex.

If you choose to have oral sex,

  • use a latex condom on the penis; or
  • if you or your partner is allergic to latex, a plastic (polyurethane) condom can be used.
Research has shown the effectiveness of latex condoms used on the penis for preventing the transmission of HIV. Condoms are not risk-free, but they greatly reduce your risk of becoming HIV-infected if your partner has the virus.

If you choose to have oral sex and you are female,

  • use a latex barrier (such as a cut-open condom that makes a square or a dental dam) between their mouth and the vagina. Plastic food wrap can also be used as a barrier.
The barrier reduces the risk of blood entering the body through the vagina. For more information about latex condoms, female condoms, and plastic (polyurethane) condoms, see "Facts about Condoms and Their Use in Preventing HIV Infection and Other STDs."

If you have personal issues concerning HIV and AIDS and wish to speak to an information specialist to discuss risk factors and how to prevent HIV transmission, you may call the CDC National AIDS Hotline 24 hours a day, 365 days a year at:

  • 1-800-342-AIDS (1-800-342-2437)
  • 1-800-AIDS-TTY (1-800-243-7889) TTY
  • 1-800-344-SIDA (1-800-344-7432) Spanish

Does circumcision effect the risk of contracting HIV? Return to top

Various groups have looked at numerous possible factors associated with HIV infection and AIDS, including circumcision. Some scientists have reported associations between circumcision and HIV infection and AIDS, while other have found no independent relationship.

Extensive research needs to be accomplished in all aspects of possible co-factors and HIV infection and AIDS before any conclusions can be made.

How is HIV transmitted heterosexually? Return to top

HIV is transmitted from men to women and women to men during vaginal intercourse. Worldwide, heterosexual transmission is the route by which most persons with AIDS have become infected with HIV. As of the end of December 1998, a total of 688,200 cases of AIDS had been reported to CDC. Of these, 66,490 (10%) occurred in adults/adolescents who reported specific heterosexual contact with a partner at risk for or known to have HIV infection. This category of AIDS cases is among the most rapidly increasing.

Most of the heterosexual contact cases reported as of the end of December 1998 reported having sex with an HIV-infected person, risk not specified (35,748), or reported having sex with an injecting drug user (26,246). Other contacts included sex with bisexual male (3,132); sex with transfusion recipient with HIV infection (935); and sex with person with hemophilia (429).

Both AIDS surveillance and HIV seroprevalence follow-up studies indicate that a significant portion of HIV infection among women in the United States is acquired through heterosexual contact. Because HIV seroprevalence is greater in men, a woman is more likely than a man to have an infected heterosexual partner. Additionally, a recent study by CDC researchers and colleagues has identified heterosexual HIV transmission to be a major public health problem for young inner city men and women who smoke crack cocaine.

It seems likely that the risk of HIV infection for heterosexuals will continue to be greatest for men and women who inject drugs and for their sex partners. Urban populations with high rates of drug use and sexually transmitted diseases can be expected to experience increasing heterosexual transmission if prevention efforts are not implemented.

Is there a connection between HIV and other sexually transmitted diseases? Return to top

Yes. Having a sexually transmitted disease (STD) can increase a person's risk of becoming infected with HIV, whether the STD causes open sores or breaks in the skin (e.g., syphilis, herpes, chancroid) or does not cause breaks in the skin (e.g., chlamydia, gonorrhea).

If the STD infection causes irritation of the skin, breaks or sores may make it easier for HIV to enter the body during sexual contact. Even when the STD causes no breaks or open sores, the infection can stimulate an immune response in the genital area that can make HIV transmission more likely.

In addition, if an HIV-infected person also is infected with another STD, that person is three to five times more likely than other HIV-infected persons to transmit HIV through sexual contact.

Not having (abstaining from) sexual intercourse is the most effective way to avoid STDs, including HIV. For those who choose to be sexually active, the following HIV prevention activities are highly effective:

  • Engaging in sex that does not involve vaginal, anal, or oral sex
  • Having intercourse with only one uninfected partner
  • Using latex condoms every time you have sex
For more information on latex condoms, the female condom, and plastic (polyurethane) condoms, see "Facts about Condoms and Their Use in Preventing HIV Infection and Other STDs."

For more information about the connection between HIV and other STDs, see "The Role of STD Testing and Treatment in HIV Prevention."

If you have personal issues concerning sexually transmitted diseases (STDs) and wish to speak to an information specialist to discuss risk factors and how to prevent STD transmission, you may call the CDC National STD Hotline, Monday through Friday, 8 a.m. to 11 p.m. (ET) at:

  • 1-800-227-8922
  • 1-800-243-7889 TTY
  • 1-800-344-7432 Spanish

What is the risk of contracting HIV from a single sexual contact? Return to top

CDC is unaware of any definitive studies which have determined the risk of HIV transmission during a single sexual contact. A person's risk of acquiring HIV infection through sexual contact is dependent on three factors: 1) the number of different sex partners; 2) the prevalence of HIV infection in these partners; and 3) the probability of viral transmission during sexual contact with an infected partner. Transmission of HIV has been reported after only one sexual contact with an infected partner, but studies indicate that many persons remain uninfected despite hundreds of contacts with an infected partner. This suggests that unexplained biologic or behavioral factors may affect the efficiency of transmission.

What can an HIV positive person do to avoid reinfection during sex? Return to top

Persons infected with HIV should use a latex condom during every act of sexual intercourse to reduce the risk of acquisition of cytomegalovirus, herpes simplex virus, and human papillomavirus, as well as other sexually transmitted pathogens. Condom use also will, theoretically, reduce the risk of acquisition of human herpesvirus 8, as well as superinfection with an HIV strain that has become resistant to antiretroviral drugs and will prevent transmission of HIV and other sexually transmitted pathogens to others. Data regarding the use and efficacy of "female condoms" are incomplete, but these devices should be considered as a risk-reduction strategy.

Persons with HIV should avoid sexual practices that may result in oral exposure to feces (e.g., oral-anal contact) to reduce the risk of intestinal infections (e.g., cryptosporidiosis, shigellosis, campylobacteriosis, amebiasis, giardiasis, and hepatitis A and B).

For further information refer to the June 27, 1997 Morbidity and Mortality Weekly Report, 1997 USPHS/IDSA Guidelines for the Prevention of Opportunistic Infections in Persons Infected with Human Immunodeficiency Virus (Vol 46: RR-12: page 38).

Can an opportunistic infections be transmitted from a person with AIDS to a person without AIDS? Return to top

So-called "opportunistic" infections are usually not a threat to a healthy immune system. These infections are caused by certain bacteria, protozoa, fungi, and other viruses and malignancies that are found commonly in the environment and that are destroyed easily by a properly functioning immune system. They are a threat to persons with HIV infection because their immune systems have been damaged by HIV. Patients with a severe underlying illness or with a preexisting immunological impairment are also susceptible to opportunistic infections.

Are embalmers or morgue workers at risk for HIV transmission? Return to top

CDC has listed three incidents where there has been a possible occupational exposure to HIV by embalmers/morgue technicians. However, the chemical germicides in embalming fluids have been tested and found to completely inactivate HIV. CDC has also published occupational infection control guidelines that apply to mortuary workers, including embalmers.

Are sanitation workers at risk for HIV transmission? Return to top

None of the diagnosed cases of AIDS reported to the CDC from all 50 States, the District of Columbia, and U.S. territories are attributable to occupational exposures incurred in sewage treatment or maintenance or have occurred in plumbers. In 1989, CDC published Guidelines for Prevention of Transmission of Human Immunodeficiency Virus and Hepatitis B to Health-Care and Public-Safety Workers. Existing standard practices of industrial hygiene that apply to plumbers or sewer- or wastewater-related occupations are sufficient to prevent the transmission of this and other bloodborne viruses.

Can I get HIV from getting a tattoo or through body piercing? Return to top

A risk of HIV transmission does exist if instruments contaminated with blood are either not sterilized or disinfected or are used inappropriately between clients. CDC recommends that instruments that are intended to penetrate the skin be used once, then disposed of or thoroughly cleaned and sterilized.

Personal service workers who do tattooing or body piercing should be educated about how HIV is transmitted and take precautions to prevent transmission of HIV and other blood-borne infections in their settings. If you are considering getting a tattoo or having your body pierced, ask staff at the establishment what procedures they use to prevent the spread of HIV and other blood-borne infections, such as hepatitis B virus. You also may call the local health department to find out what sterilization procedures are in place in the local area for these types of establishments.

I have read on the Internet several stories about people getting stuck by needles in phone booth coin returns, movie theater seats, and other places. One story said that CDC reported similar incidents about improperly discarded needles and syringes. Are these stories true? Return to top

CDC has received inquiries about a variety of reports or warnings about used needles left by HIV-infected injection drug users in coin return slots of pay phones and movie theater seats. These reports and warnings are being circulated on the Internet and by e-mail and fax. Some reports have falsely indicated that CDC "confirmed" the presence of HIV in the needles. CDC has not tested such needles nor has CDC confirmed the presence or absence of HIV in any sample related to these rumors.

The majority of these reports and warnings appear to have no foundation in fact.

CDC recently was informed of one incident in Virginia of a needle stick from a small-gauge needle (believed to be an insulin needle) in a coin return slot of a pay phone. The incident was investigated by the local police department. Several days later, after a report of this police action appeared in the local newspaper, a needle was found in a vending machine but did not cause a needle-stick injury.

Discarded needles are sometimes found in the community outside of health care settings. These needles are believed to have been discarded by persons who use insulin or are injection drug users. Occasionally the "public" and certain groups of workers (e.g., sanitation workers or housekeeping staff) may sustain needle-stick injuries involving inappropriately discarded needles.

Needle-stick injuries can transfer blood and blood-borne pathogens (e.g., hepatitis B, hepatitis C, and HIV), but the risk of transmission from discarded needles is extremely low. CDC does not recommend testing discarded needles to assess the presence or absence of infectious agents in the needles. Management of exposed persons should be done on a case-by-case evaluation of (1) the risk of a blood-borne pathogen infection in the source and (2) the nature of the injury. Anyone who is injured from a needle stick in a community setting should contact their physician or go to an emergency room as soon as possible. The injury should be reported to the local or state health departments.

CDC is not aware of any cases where HIV has been transmitted by a needle-stick injury outside a health care setting.

Should I be concerned about getting infected with HIV while playing sports? Return to top

There are no documented cases of HIV being transmitted during participation in sports. The very low risk of transmission during sports participation would involve sports with direct body contact in which bleeding might be expected to occur.

If someone is bleeding, their participation in the sport should be interrupted until the wound stops bleeding and is both antiseptically cleaned and securely bandaged. There is no risk of HIV transmission through sports activities where bleeding does not occur.