HIV transmission risk is often misunderstood. The risk of HIV transmission is only present in certain conditions. HIV transmission may occur if you have sexual contact (usually penetrative sex) with an HIV positive person or if you share injecting equipment such as needles or syringes with someone who is infected with HIV. In addition and now thankfully rarely in the major Western Countries, it is possible to become infected with HIV through use of HIV infected blood products. HIV testing is a key way to know your status and prevent infection. We can perform accurate HIV testing from as early as 10 days after infection.
How is HIV Spread?
- HIV is most commonly spread by unprotected (without a condom) penetrative sex which may be vaginal or anal and which occurs between an HIV positive and an HIV negative person.
Reducing HIV Risk
- The two most effective things people can do to reduce HIV transmission risk as much as possible are to always use good quality condoms with lubrication for penetrative sex and to know their HIV status by having regular HIV tests.
- Unprotected anal sex carries the greatest risk for the receptive (the person being penetrated) partner. This is because the anal and rectal canals are more delicate than vaginal tissue and the membranes are likely to bleed. In addition, the rectum is designed to maintain fluid balance by absorbing fluid. The result is that if HIV infected semen is left in the rectum, the blood-rich membranes will quickly allow the fluid and any virus to be absorbed. Other STD’s which might be present like gonorrhoea, syphilis, Chlamydia and especially herpes will help boost the infection with HIV.
- The HIV transmission risk is increased if the HIV positive person has acquired their infection in the fairly recent past. The chances of HIV transmission are increased greatly during the early period after initial infection. This is because people who have been recently infected with HIV will have very high levels of HIV in their blood and semen and other body fluids. This high level of HIV is referred to as the HIV “viral load” and will in the early stages of HIV infection HIV viral load will run at extremely high levels of perhaps several million copies (“copies” are viral particles) per ml of blood. As the infection goes on and the body adjusts to the new infection, the viral load will drop to perhaps several tens of thousands of copies. This usually happens at perhaps three to six months after initial HIV infection. The risk of HIV transmission drops as the viral load drops.
- HIV transmission will reduce very markedly if an HIV positive person is taking optimal treatment with what are called Anti-retroviral medications. These will ideally suppress the viral load to undetectable levels. There is good evidence to suggest that the infectivity of people who have undetectable viral loads is negligible.
- HIV transmission risk will increase if you have sex with people at high risk for having HIV. It sounds very obvious, doesn’t it, but in fact most people have very little idea as to the true risks of sexual activity. Researchers writing in the New England Journal of Medicine in February (El-Sadr www.nejm.org February 10, 2010) pointed out that in some parts of the United States the HIV prevalence rate can be as high as 30% (some urban areas and in populations of men who have sex with men). There is a common view that having sex in Africa poses a very high risk but the authors point out that actually the general population prevalence in say Kenya or S Africa is much lower. The key then is to understand the risk if you can but always to try to protect yourself by using well lubricated condoms.
- HIV transmission chances are higher if you are exposed at the same time to other Sexually Transmitted Infections such as herpes, gonorrhoea, syphilis and Chlamydia or if you already have one of these infections. Regular STD screening and testing with treatment will allow you to identify other STD’s / STI’s and treatment may well help protect you against acquiring something more sinister such as HIV.
- HIV transmission risk through oral sex is very, very low. There have been reports of HIV being transmitted from an HIV positive male to an HIV negative partner by sucking. These reports have been anecdotal – i.e. not scientific studies and the numbers have been very small indeed. Several well constructed studies have tried to define the risk but in these studies, despite many thousands of oral “episodes” between an HIV positive and an HIV negative partner, there have not been any new infections in the study groups.
- HIV transmission chances through oral sex seem likely on a common sense basis alone to be increased by poor oral hygiene; other STD’s such as herpes etc as described above. So having regular STD screening tests and also visiting the dentist and maintaining good oral health is likely to further protect you against HIV.