These are the main ways in which someone can become infected with HIV:

• Unprotected penetrative sex with someone who is infected.
• Injection or transfusion of contaminated blood or blood products, donations of semen (artificial insemination), skin grafts or organ transplants taken from someone who is infected.
• From a mother who is infected to her baby; this can occur during pregnancy, at birth and through breastfeeding.
• Sharing unsterilised injection equipment that has previously been used by someone who is infected.

No. Like all sexually transmitted infections, HIV cannot be 'created', only passed on. If you are sure that your partner does not have HIV, then there is no risk of acquiring it, even if you do have unprotected sex (whether it be vaginal, anal or oral). However, pregnancy and other sexually transmitted diseases (if your partner has one) remain a risk, so you should still use a condom or other suitable form of birth control wherever possible.

Although it is possible to become infected with HIV through oral sex, the risk of becoming infected in this way is much lower than the risk of infection via unprotected sexual intercourse with a man or woman.

When giving oral sex to a man (sucking or licking a man's penis) a person could become infected with HIV if infected semen came into contact with damaged and receding gums, or any cuts or sores they might have in their mouth.

Giving oral sex to a woman (licking a woman's vulva or vagina) is also considered relatively low risk. Transmission could take place if infected sexual fluids from a woman got into the mouth of her partner. The likelihood of infection might be increased if there is menstrual blood involved or if the woman is infected with another sexually transmitted disease.

The likelihood of either a man or a woman becoming infected with HIV as a result of receiving oral sex is extremely low, as saliva does not contain infectious quantities of HIV.

More information can be found in our oral sex & HIV page.

Whilst research suggests that high concentrations of HIV can sometimes be detected in precum, it is difficult to judge whether HIV is present in sufficient quantities for infection to occur. To guard against the possibility of infection with HIV or any other STD it is best to practise safer sex, i.e. sex with a condom.

Deep or open-mouthed kissing is a very low risk activity in terms of HIV transmission. HIV is only present in saliva in very minute amounts, insufficient to cause infection with HIV.

There has been only one documented case of someone becoming infected with HIV through kissing; a result of exposure to infected blood during open-mouthed kissing. If you or your partner have blood in your mouth, you should avoid kissing until the bleeding stops.

Lesbians/bisexual women are not at high risk of contracting HIV through woman-to-woman sex. Very few women are known to have passed HIV on to other women sexually, though it is theoretically possible if infected vaginal fluids or blood from an HIV positive partner enter the other woman's vagina (perhaps on fingers or sex toys).

AVERT has more information about lesbians, bisexual women & HIV.

Unprotected anal intercourse does carry a higher risk than most other forms of sexual activity. The lining of the rectum has fewer cells than that of the vagina, and therefore can be damaged more easily, causing bleeding during intercourse. This can then be a route into the bloodstream for infected sexual fluids or blood. There is also a risk to the insertive partner during anal intercourse, though this is lower than the risk to the receptive partner.

Inserting a finger into someone's anus or vagina would only be an HIV risk if the finger had cuts or sores on it and if there was direct contact with HIV infected blood, vaginal fluids or semen from the other person. There might also be a risk if the person doing the fingering had HIV and their finger was bleeding.

HIV and other STDs can impact upon each other. The presence of STDs in an HIV infected person can increase the risk of HIV transmission. This can be through a genital ulcer which could bleed or through increased genital discharge.

An HIV negative person who has an STD can be at increased risk of becoming infected with HIV through sex. This can happen if the STD causes ulceration or breaks in the skin (e.g. syphilis or herpes), or if it stimulates an immune response in the genital area (e.g. chlamydia or gonorrhea). HIV transmission is more likely in those with ulcerative STDs than non-ulcerative.

Using condoms during sex is the best way to prevent the sexual transmission of diseases, including HIV. AVERT.org has more information on STDs.

No. HIV is not an airborne, water-borne or food-borne virus, and does not survive for very long outside the human body. Therefore ordinary social contact such as kissing, shaking hands, coughing and sharing cutlery does not result in the virus being passed from one person to another.

There have been a number of stories circulating via the Internet and e-mail, about people becoming infected from needles left on cinema seats and in coin return slots. These rumours appear to have no factual basis.

For HIV infection to take place in this way the needle would need to contain infected blood with a high level of infectious virus. If a person was then pricked with an infected needle, they could become infected, but there is still only a 0.4% chance of this happening.

Although discarded needles can transfer blood and blood-borne illnesses such as Hepatitis B, Hepatitis C and HIV, the risk of infection taking place in this way is extremely low.

Further information on this topic can be found on the CDC website.

If instruments contaminated with blood are not sterilised between clients then there is a risk of HIV transmission. However, people who carry out body piercing or tattooing should follow procedures called 'universal precautions', which are designed to prevent the transmission of blood borne infections such as HIV and Hepatitis B.

When visiting the barbers there is no risk of infection unless the skin is cut and infected blood gets into the wound. Traditional 'cut-throat' razors used by barbers now have disposable blades, which should only be used once, thus eliminating the risk from blood-borne infections such as Hepatitis and HIV.

The risk to healthcare workers being exposed to HIV is extremely low, especially if they follow universal healthcare precautions. Everyday casual contact does not expose anyone, including healthcare workers, to HIV. The main risk is through accidental injuries from needles and other sharp objects that may be contaminated with HIV.

It has been estimated that the risk of infection from a needlestick injury is less than 1 percent. In the UK for instance, there have been five documented cases of HIV transmission through occupational exposure in the healthcare setting, the last being in 1999. In the US, there were 57 documented cases of occupational HIV transmission up to 2006.

The risk posed by a needlestick injury may be higher if it is a deep injury; if it is made with a hollow bore needle; if the source patient has a high viral load; or if the sharp instrument is visibly contaminated with blood. For further information, see our HIV and healthcare workers page.

Transmission of HIV in a healthcare setting is extremely rare. All health professionals are required to follow infection control procedures when caring for any patient. These procedures are called universal precautions for infection control. They are designed to protect both patients and healthcare professionals from the transmission of blood-borne diseases such as Hepatitis B and HIV.

Research suggests that the risk of HIV infection in this way is extremely small. A very small number of people - usually in a healthcare setting - have become infected with HIV as a result of blood splashes in the eye.

Blood in the mouth carries an even lower risk. The lining of the mouth is very protective, so the only way HIV could enter the bloodstream would be if the person had a cut, open sore or area of inflammation somewhere in their mouth or throat (if the blood was swallowed). Even then, the person would have to get a fairly significant quantity of fresh blood (i.e. an amount that can be clearly seen or tasted) directly into the region of the cut or sore for there to be a risk. HIV is diluted by saliva and easily killed by stomach acid once the blood is swallowed.

Infection with HIV in this way is unusual. There have only been a couple of documented cases of HIV transmission resulting from biting. In these particular cases, severe tissue tearing and damage were reported in addition to the presence of blood.

No. HIV is a Human Immunodeficiency Virus. It only affects humans. There are some other types of immunodeficiency viruses that specifically affect cats and other primates, namely the Feline Immunodeficiency Virus (FIV) and Simian Immunodeficiency Virus (SIV). These viruses are of no risk to humans.

Some people have expressed concern that they could become infected if scratched by an animal that has previously scratched an HIV positive person. This is exceptionally unlikely, and there are no documented cases of transmission occurring in this way.

No, it is not possible to get HIV from mosquitoes. When taking blood from someone, mosquitoes do not inject blood from any previous person. The only thing that a mosquito injects is saliva, which acts as a lubricant and enables it to feed more efficiently.

HIV is overwhelmingly transmitted through sexual contact, through intravenous drug use, through infected blood donations and from mother to child during pregnancy, birth and breastfeeding. HIV is not transmitted through everyday social contact. There have however been a few cases in which it is thought that family members have infected each other through ways other than those stated above.

A case in Australia in the late 1990s involved two sisters. Both tested positive within a month of each other. The risk exposure for the older sister was identified as being sexual contact she had with a Russian man. The younger sister had had no obvious risk exposures, and investigators concluded that the only possible risk exposure was them sharing a razor to shave their legs. Further analysis established that they did have the same Russian virus strain, not commonly found in Australia.

The other case involved a mother and son, again in Australia, who both tested HIV positive. He had had risk exposures in Thailand some years before, whereas the mother could not identify a possible exposure. The son had had the skin condition psoriasis some time earlier, and the mother's application of the cream to his skin lesions was identified as the only possible route of infection. Analysis showed that they both had the same strain, found in Thailand and not common in Australia.

Whilst HIV transmission between family members and members of the same household is possible, it occurs in extremely low numbers and documented cases are very rare.

There is a possibility of becoming infected with HIV if you share injecting equipment with someone who has the virus. If HIV infected blood remains within the bore (inside) of the needle or in the syringe and someone else then uses it to inject themselves, that blood can be flushed into the bloodstream. Sharing needles, syringes, spoons, filters or water can pass on the virus. Disinfecting equipment between uses can reduce the likelihood of transmission, but does not eliminate it. More information can be found in our Injecting drugs, drug users and HIV page.

An HIV-infected pregnant woman can pass the virus on to her unborn baby either before or during birth. HIV can also be passed on during breastfeeding. If a woman knows that she is infected with HIV, there are drugs she can take to greatly reduce the chances of her child becoming infected. Other ways to lower the risk include choosing to have a caesarean section delivery and not breastfeeding. Read more about HIV and pregnancy.

Some people have been infected through a transfusion of infected blood. In most countries, however, all the blood used for transfusions is now tested for HIV. In those countries where the blood has been tested, HIV infection through blood transfusions is now extremely rare. Blood products, such as those used by people with haemophilia, are now heat-treated to make them safe.

Donating blood at an approved donation centre should carry no risk, as all equipment should be sterile and blood collection needles are not reused.

Whilst HIV may live for a short while outside of the body, HIV transmission has not been reported as a result of contact with spillages or small traces of blood, semen or other bodily fluids. This is partly because HIV dies quite quickly once exposed to the air, and also because spilled fluids would have to get into a person's bloodstream to infect them.

Scientists agree that HIV does not survive well in the environment, making the chance of environmental transmission remote. To obtain data on the survival of HIV, laboratory studies usually use artificially high concentrations of laboratory-grown virus. Although these concentrations of HIV can be kept alive for days or even weeks under controlled conditions, studies have shown that drying of these high concentrations of HIV reduces the amount of infectious virus by 90 to 99 percent within a few hours.

Since the HIV concentrations used in laboratory studies are much higher than those actually found in blood or other specimens, the real risk of HIV infection from dried bodily fluids is probably close to zero. Incorrect interpretation of conclusions drawn from laboratory studies have unnecessarily alarmed some people. AVERT.org has additional facts about HIV and AIDS.

There is very strong evidence showing that circumcised men are about half as likely as uncircumcised men to acquire HIV through heterosexual sex. However, circumcision does not make a man immune to HIV infection, it just means that it's less likely to happen. Male circumcision probably has little or no preventive benefit for women. Read more about HIV and circumcision.

Even if your tests show that you have very low levels of HIV in your blood, the virus will not have been totally eradicated and you will still be capable of infecting others. Some drugs do not penetrate the genitals very well and so do not disable HIV as effectively there as they do in the blood. This means that while you may have little active virus showing up on blood tests, there may still be quite a lot of HIV in your semen or vaginal fluids. Transmission may be less likely when you have a low viral load, but it is still possible so you should always take appropriate precautions.

For more information on this issue read AVERT's HIV transmission and antiretroviral therapy briefing sheet.

Currently, there does not seem to be a greater risk of contracting Swine flu if you are HIV positive but as with all types of flu, there can be complications. It is normal for health services to advise that those living with HIV receive a flu vaccine annually and this is also the case for swine flu.

It has not been confirmed whether those with a CD4 cell count of less than 200 will be at a greater risk of complications but they should always seek medical advice from their HIV clinic if they start to suffer from flu like symptoms which persist or worsen despite antiretroviral treatment. It can be the case that they are not suffering from swine flu or flu but instead the symptoms could be an opportunistic infection, mistaken for flu.

On February 6, 1994, the Columbia Gay Health Advocacy Project (CGHAP) sponsored a conference entitled Oral Sex and Possible HIV Transmission. This conference was co-sponsored by the Gay Men's Health Crisis (GMHC). The event was held at MillerTheater on the Columbia University campus and ran from 2 PM to 6PM. More than 500 people attended the conference. The program consisted of a series of speakers presenting available scientific data, and a panel of community members discussing psychological, social, and educational aspects of the issue. There was extended time for questions and lively discussion from the audience.

The first group of speakers talked about the mechanics of transmission by oral sex. The speakers were Jeffrey Laurence, M.D., (New York Hospital-Cornell Medical Center), Alison Quayle, Ph.D. (Harvard University) and Peter Schlegel, M.D., and Gerard Ilaria, A.C.S.W. (New York Hospital-Cornell Medical Center).

Jeffrey Laurence, M.D.
Biology and Virology.

Dr. Jeffrey Laurence explained that studies have shown that a reliable laboratory can isolate HIV in the saliva samples of about 25% of HIV-positive people. The same labs can isolate HIV in 100% of blood samples from the same people. In those saliva samples in which virus can be found, the concentration of virus is much lower than in blood, semen, or the already low concentrations found in vaginal or cervical secretions. The low concentration of virus in saliva may mean that saliva is less likely to cause infection than blood or other body fluids. This is certainly supported by test tube and animal studies of infectivity.

Why is saliva less infectious than other fluids? It is believed that there is a substance in saliva that inhibits HIV. The inhibition observed may be due to large sugar-protein molecules in the saliva called glycoproteins. These glycoproteins apparently cause HIV to form giant clumps which are not capable of causing infection.

Alison Quayle, Ph.D.
Mucous Membranes

The next speaker, Dr. Alison Quayle, gave an overview of the mucous membranes and the way in which they protect the body from bacteria, viruses, and fungi. Because the mucous membranes are the surfaces of the body which communicate with the outside world, they are subject to a barrage of these organisms. Mucous membranes defend the body against infection by both nonspecific defenses and defenses specific to particular organisms. The nonspecific defenses include a sticky mucous that forms a physical barrier between the outside and the mucous membrane. The body also contains multiple "clearing mechanisms" for getting rid of infected material (cilia in the respiratory tract, peristalsis in the gut). Gastric acid in stomach kills most bacteria and viruses. Mucous surfaces also contain substances referred to as the body's disinfectants that either kill bacteria or viruses or prevent them from multiplying.

The specific defense tactic of the mucosal surfaces is the mucosal immune system. Mucosal secretions contain a class of antibodies called immunoglobulin A (IgA, or secreted antibodies). IgA secreted in mucous binds and neutralizes pathogens such as bacteria and viruses on mucosal surfaces. The mucous linings of the vagina and oral cavity have more layers than the lining of the rectum. The linings of the vagina and oral cavity are therefore more likely to provide protection against the entry of pathogens.

Dr. Quayle reviewed various body secretions, whether they contain virus, and their ability to transmit HIV. She distinguished between the presence of the virus in a body fluid and its infectivity, that is, its ability to multiply and transmit infection. Infectious virus can be identified by culturing susceptible cells in the laboratory and exposing these cells to the body fluid being tested.

HIV-infected blood is highly infectious. HIV-infected semen is also infectious, but less so than blood, according to Dr. Quayle. Studies have reported the presence of HIV in 30% of semen samples. These studies also report that at any particular point in time only about 10% of HIV-infected semen samples contain HIV capable of infecting cells in culture. Semen appears to be more likely to be infectious in men whose HIV infection is recent (6-12 weeks) and in those with advanced HIV disease. However, studies show that HIV-infected men who are asymptomatic are also capable of producing infectious ejaculate. The presence of an inflammation in an HIV-infected man increases the number of infected white blood cells in the semen and thus increases the infectivity of the ejaculate. Treatment with zidovudine (AZT) can decrease the amount of infectious virus in semen.

Studies have shown that about 20% of the HIV-infected women studied have infectious virus in their vaginal secretions at any particular point in time. HIV-infected women are more likely to transmit the virus during their menstrual period. This is because women secrete about a half-cup of blood during menses and blood is very infectious.

Saliva, as Dr. Laurence described above, contains very low concentrations of virus, possibly due to an unidentified inhibitory factor in saliva. Nevertheless, infectious virus has been found in the saliva of some HIV-infected people. The presence of blood in saliva (or any body fluid) probably increases infectivity. Lesions, ulcers, and inflammations caused by other sexually transmitted diseases make the mucous membranes more susceptible to infection. Urine rarely contains infectious virus. HIV can be detected in feces but cannot be cultured in the lab and may not be infectious.

Peter Schlegel, M.D., and Gerard Ilaria, A.C.S.W.
Pre-ejaculatory Fluid

Peter Schlegel and Gerard Ilaria presented information from their study of pre-ejaculatory fluid and HIV. This study (and a second similar one done by Dr. Jeffrey Pudney at Harvard) showed the presence of HIV-infected cells in pre-ejaculatory fluid. However, the cells were not cultured and may or may not have been infectious. Schlegel and Ilaria described the difficulties in performing studies of pre-ejaculatory fluid and the pressing need for further research about this neglected but important topic.

The next section of the conference consisted of presentations by three epidemiologists, Dr. Alan Lifson (University of Minnesota), Dr. Michael Samuel (New Mexico Department of Health), and Rebecca Young (Columbia University).

Michael Samuel, Dr. P.H., and Alan R. Lifson, M.D., M.P.H.
What Does Risk Mean?

Dr. Alan Lifson began by talking about the differing uses of the term "risk." In talking about infection, epidemiologists use the term "increased risk" to mean an increased likelihood that a particular exposure will lead to infection. This increased likelihood is meaningful only if it is statistically significant -- that is, unlikely to have occurred by chance alone. Statistical associations can be significant to varying degrees ranging from small to large.

There are three different questions about HIV transmission via oral sex.

• Is there any chance of infection?
• Can this chance be meaningfully quantified?
• If so, is this chance small or large as compared to other sexual activities?

Dr. Lifson and Dr. Samuel interpret the data now available to indicate that it is possible to transmit HIV during fellatio but the degree of risk is uncertain but probably low as compared to unprotected vaginal or anal intercourse. Multiple detailed case reports indicate that HIV infection can be transmitted from the insertive partner's penis to the receptive partner's mouth via fellatio with ejaculation in the mouth. There are no reports of transmission occurring without ejaculation, but some of the reports do not indicate whether ejaculation in the mouth occurred.

There are no case reports that conclusively show reports of HIV infection occurring from the receptive partner (the mouth) to the insertive partner (the penis) via fellatio. A couple of cases have been reported, but these accounts are not been detailed and it is not known whether these are reliable reports.

There is little data available about the possibility of becoming infected by putting the mouth on the vagina of an HIV-infected woman. One case of woman-to-man transmission via oral sex and several women-to-women cases have been reported, but in little detail. Dr. Lifson believes that these reports indicate that there is a possibility of infrequent transmission via cunnilingus, from vagina to mouth, but that it has not been conclusively proven.

Dr. Michael Samuel presented the information available from cross-sectional and prospective studies done concerning fellatio. All of these studies except one showed that there was no statistically significant increased risk of HIV transmission associated with fellatio. The exception was the study done by Dr. Samuel which looked at the combined data from the San Francisco Men's Health Study, The San Francisco City Clinic cohort, and the San Francisco General Hospital cohort. These data indicate that there is a statistically significant increased risk of infection via fellatio.

Dr. Samuel thinks that the difference between the results of his study and others can be explained in several ways. There may be a mistake in the Samuel's study. Alternatively, because the Samuel's study was the most recent, the increase in the relative number of people who have oral sex but not anal sex may allow the risk of oral sex to be "unmasked" and measured.

Rebecca Young
Comments on Lack of Data Regarding Women

Ms. Young addressed some of the complex issues regarding transmission from women-to-women or women-to-men via cunnilingus. Clearly, most lesbians have been infected through sex with an infected man or needle-sharing. The relatively small number of lesbians infected make it difficult to draw conclusions from the available data. There have been no large scale studies. Surveys that have been done tend to ask questions in language that is vague and confusing. The scientific community tends to have a lack of knowledge and bias about lesbians that tend to make it difficult to formulate useful surveys.

Community Panel

The final portion of the program was devoted to addressing the complex psycho-social aspects of oral sex and HIV transmission and particularly the difficulty created by ambiguity. We purposely chose a diverse panel of individuals (including both men and women who are HIV-positive and HIV-negative) to discuss these questions with the audience. The panelists were AIDS educators, activists, or policy-makers. The panel consisted of Sally Cooper, Carlos Cordero, Spencer Cox, Richard Elovich, Tonya Hall, Michael Isbell, Wendell O'Neill, and Sarah Schulman.

Some of the issues addressed by the panelists and audience were:

• There is a conflict between the standard medical advice (to use condoms and dental dams) versus the reality of practice (few people seem to use barriers for oral sex).
  
  
• AIDS educators face a dilemma. The cautious approach (use barriers for oral sex) may theoretically be the safest. However, it is possible that in practice, discouraging unprotected oral sex may lead to attitudes of frustration and despair that could increase the amount of (far more dangerous) unprotected vaginal or anal intercourse.
  
  
• Our ability to conceptualize useful approaches to safer sex is limited by the societal difficulty in discussing sexual experience in all its complexity. We may need to move beyond the "cook book" approach and begin to develop more flexible models of harm reduction in specific contexts.
  
• Lesbians face a difficult conflict. Women-to-women transmission seems fairly unlikely. There are many HIV infected lesbians who became infected either through sex with a man or needle-sharing. However, ignoring the possibility of women-to-women transmission leaves infected women (who are primarily women of color) without any guidelines. Additionally, given the long history of scientific ignorance and bias regarding lesbians, an attitude of skepticism about the data available is reasonable.
  
  
• The largest agreement among audience, scientists and community panelists was the need for increased discussion about sexual practices and safer sex. We must seek creative ways of allowing these discussions to occur in an atmosphere that encourages honesty and allows for the subtlety, diversity, and complexity of human behavior.

The conference was probably the first large-scale, open, public discussion on the topic of oral sex and HIV transmission and aroused a great deal of both interest and anxiety among the organizers and speakers. GMHC joined CGHAP as a co-sponsors after some debate about the utility of such a conference, given the fact that no clear-cut answers are available. In the end, the representatives from GMHC thought that the conference was a highly useful first step and encouraged increased discussion of the topic among the safer sex educators at GMHC. Most speakers and panelists shared this view. The informal feedback we have received from the audience has been positive.

The AIDS Reader (a free medical update on AIDS funded by Roerig) will publish portions of the conference transcript in the July issue of this journal. The AIDS Reader has a circulation of 25,000 physicians and other health care professionals. An audio tape was also made and can be ordered from GMHC by calling 212-337-3505. The conference was also videotaped and portions of it have been shown on New York cable TV. GMHC reports that it has received an unprecedented amount of requests for tapes of the conference.