Individual differences |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |
| Estimated per act risk for acquisition of HIV, |
by exposure route, assuming no condom use
|Exposure Route|| Risk per 10,000 exposures |
to an infected source
|Needle-sharing injection drug use||67 |
|Receptive anal intercourse||50 |
|Percutaneous needle stick||30 |
|Receptive penile-vaginal intercourse||10 |
|Insertive anal intercourse||6.5 |
|Insertive penile-vaginal intercourse||5 |
|Receptive oral intercourse||1 |
|Insertive oral intercourse||0.5 |
The diverse transmission routes of HIV are well-known and established. Also well-known is how to prevent transmission of HIV. However, recent epidemiological and behavioral studies in Europe and North America have suggested that a substantial minority of young people continue to engage in high-risk practices and that despite HIV/AIDS knowledge, young people underestimate their own risk of becoming infected with HIV . However, transmission of HIV between intravenous drug users has clearly decreased, and HIV transmission by blood transfusion has become quite rare in developed countries.
Prevention of sexual transmission of HIV
Unprotected receptive sexual acts are at more risk than unprotected insertive sexual acts, with the risk for transmitting HIV from an infected partner to an uninfected partner through unprotected insertive anal intercourse greater than the risk for transmission through vaginal intercourse or oral sex. Oral sex is not without its risks as it has been established that HIV can be transmitted through both insertive and receptive oral sex .
Sexually-transmitted infections (STI) increase the risk of HIV transmission and infection because they cause the disruption of the normal epithelial barrier by genital ulceration and/or microulceration; and by accumulation of pools of HIV-susceptible or HIV-infected cells (lymphocytes and macrophages) in semen and vaginal secretions. Epidemiological studies from sub-Saharan Africa, Europe and North America have suggested that there is approximately a four times greater risk of becoming HIV-infected in the presence of a genital ulcer such as caused by syphilis and/or chancroid; and a significant though lesser increased risk in the presence of STIs such as gonorrhoea, chlamydial infection and trichomoniasis which cause local accumulations of lymphocytes and macrophages .
Transmission of HIV depends on the infectiousness of the index case and the susceptibility of the uninfected partner. Infectivity seems to vary during the course of illness and is not constant between individuals. An undetectable plasma viral load does not mean that you have a low viral load in the seminal liquid or genital secretions. Each 10 fold increment of seminal HIV RNA is associated with an 81% increased rate of HIV transmission . Women are more susceptible to HIV-1 infection due to hormonal changes, vaginal microbial ecology and physiology, and a higher prevalence of sexually transmitted diseases . Also, people who are infected with HIV can still be infected by other, more virulent strains.
During a sexual act, only condoms, be they male or female, can reduce the chances of infection with HIV and other STIs and the chances of becoming pregnant. They must be used during all penetrative sexual intercourse with a partner who is HIV positive or whose status is unknown . The effective use of condoms and screening of blood transfusion in North America, Western and Central Europe is credited with the low rates of AIDS in these regions.
Promoting condom use, however, has often proved controversial and difficult. Many religious groups, most visibly the Roman Catholic Church, have opposed the use of condoms on religious grounds, and have sometimes seen condom promotion as an affront to the promotion of marriage, monogamy and sexual morality. Other religious groups have argued that preventing HIV infection is a moral task in itself and that condoms are therefore acceptable or even praiseworthy from a religious point of view.
The male latex condom is the single most efficient available technology to reduce the sexual transmission of HIV and other sexually transmitted infections. In order to be effective, they must be used correctly during each sexual act. Lubricants containing oil, such as petroleum jelly, or butter, must not be used as they weaken latex condoms and make them porous. If necessary, lubricants made from water are recommended. However, it is not recommended to use a lubricant for fellatio. Also, condoms have standards and expiration dates. It is essential to check the expiration date and if it conforms to European (EC 600) or American (D3492) standards before use.
The female condom is an alternative to the male condom and is made from polyurethane, which allows it to be used in the presence of oil-based lubricants. They are larger than male condoms and have a stiffened ring-shaped opening, and are designed to be inserted into the vagina. The female condom also contains an inner ring which keeps the condom in place inside the vagina - inserting the female condom requires squeezing this ring. With consistent and correct use of condoms, there is a very low risk of HIV infection. Studies on couples where one partner is infected show that with consistent condom use, HIV infection rates for the uninfected partner are below 1% per year .
The U.S. government and U.S. health organizations both endorse the ABC Approach to lower the risk of acquiring AIDS during sex:
- Abstinence or delay of sexual activity, especially for youth,
- Being faithful, especially for those in committed relationships,
- Condom use, for those who engage in risky behavior.
This approach has been very successful in Uganda, where HIV prevalence has decreased from 15% to 5%. However, the ABC approach is far from all that Uganda has done, as "Uganda has pioneered approaches towards reducing stigma, bringing discussion of sexual behavior out into the open, involving HIV-infected people in public education, persuading individuals and couples to be tested and counseled, improving the status of women, involving religious organizations, enlisting traditional healers, and much more." (Edward Green, Harvard medical anthropologist). Also, it must be noted that there is no conclusive proof that abstinence-only programs have been successful in any country in the world in reducing HIV transmission. This is why condom use is heavily co-promoted. There is also considerable overlap with the CNN Approach. This is:
- Condom use, for those who engage in risky behavior.
- Needles, use clean ones
- Negotiating skills; negotiating safer sex with a partner and empowering women to make smart choices
The ABC approach has been criticized, because a faithful partner of an unfaithful partner is at risk of AIDS . Many think that the combination of the CNN approach with the ABC approach will be the optimum prevention platform.
Current research is clarifying the relationship between male circumcision and HIV in differing social and cultural contexts. UNAIDS believes that it is premature to recommend male circumcision services as part of HIV prevention programmes . Moreover, South African medical experts are concerned that the repeated use of unsterilised blades in the ritual circumcision of adolescent boys may be spreading HIV .
Prevention of blood or blood product route of HIV transmission
Sharing and reusing syringes contaminated with HIV-infected blood represents a major risk for infection with not only HIV but also hepatitis B and hepatitis C. In the United States a third of all new HIV infections can be traced to needle sharing and almost 50% of long-term addicts have hepatitis C. The risk of being infected with HIV from a single prick with a needle that has been used on an HIV infected person though is thought to be about 1 in 150 (see table above). Post-exposure prophylaxis with anti-HIV drugs can further reduce that small risk . Universal precautions are frequently not followed in both sub-Saharan Africa and much of Asia because of both a shortage of supplies and inadequate training. The WHO estimates that approximately 2.5% of all HIV infections in sub-Saharan Africa are transmitted through unsafe healthcare injections . Because of this, the United Nations General Assembly, supported by universal medical opinion on the matter, has urged the nations of the world to implement universal precautions to prevent HIV transmission in health care settings .
In countries where improved donor selection and antibody tests have been introduced, the risk of transmitting HIV infection to blood transfusion recipients is extremely low. But according to the WHO, the overwhelming majority of the world's population does not have access to safe blood and "between 5% and 10% of HIV infections worldwide are transmitted through the transfusion of infected blood and blood products" .
Medical workers who follow universal precautions or body substance isolation such as wearing latex gloves when giving injections and washing the hands frequently can help prevent infection of HIV.
All AIDS-prevention organizations advise drug-users not to share needles and other material required to prepare and take drugs (including syringes, cotton balls, the spoons, water for diluting the drug, straws, crack pipes etc). It is important that people use new or properly sterilized needles for each injection. Information on cleaning needles using bleach is available from health care and addiction professionals and from needle exchanges. In the United States and some other countries, clean needles are available free in some cities, at needle exchanges or safe injection sites. Additionally, many states within the United States and some other nations have decriminalized needle possession and made it possible to buy injection equipment from pharmacists without a prescription.
Mother to child transmission
There is a 15–30% risk of transmission of HIV from mother to child during pregnancy, labour and delivery . In developed countries the risk can of transmission of HIV from mother to child can be as low as 0-5%. A number of factors influence the risk of infection, particularly the viral load of the mother at birth (the higher the load, the higher the risk). Breastfeeding increases the risk of transmission by 10–15%. This risk depends on clinical factors and may vary according to the pattern and duration of breastfeeding.
Studies have shown that antiretroviral drugs, cesarean delivery and formula feeding reduce the chance of transmission of HIV from mother to child . When replacement feeding is acceptable, feasible, affordable, sustainable and safe, HIV-infected mothers are recommended to avoid breast feeding their infant. Otherwise, exclusive breastfeeding is recommended during the first months of life and should be discontinued as soon as possible .
References & Bibliography
- ↑ Donegan, E., Stuart, M., Niland, J. C., Sacks, H. S., Azen, S. P., Dietrich, S. L., Faucett, C., Fletcher, M. A., Kleinman, S. H., Operskalski, E. A., et al. (1990). Infection with human immunodeficiency virus type 1 (HIV-1) among recipients of antibody-positive blood donations. Ann. Intern. Med. 113 (10): 733-739. PMID 2240875.
- ↑ Kaplan, E. H. and Heimer, R. (1995). HIV incidence among New Haven needle exchange participants: updated estimates from syringe tracking and testing data. J. Acquir. Immune Defic. Syndr. Hum. Retrovirol. 10 (2): 175-176. PMID 7552482.
- ↑ 3.0 3.1 3.2 3.3 European Study Group on Heterosexual Transmission of HIV (1992). Comparison of female to male and male to female transmission of HIV in 563 stable couples. BMJ. 304 (6830): 809-813. PMID 1392708.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Varghese, B., Maher, J. E., Peterman, T. A., Branson, B. M. and Steketee, R. W. (2002). Reducing the risk of sexual HIV transmission: quantifying the per-act risk for HIV on the basis of choice of partner, sex act, and condom use. Sex. Transm. Dis. 29 (1): 38-43. PMID 11773877.
- ↑ Bell, D. M. (1997). Occupational risk of human immunodeficiency virus infection in healthcare workers: an overview.. Am. J. Med. 102 (5B): 9-15. PMID 9845490.
- ↑ Leynaert, B., Downs, A. M. and de Vincenzi, I. (1998). Heterosexual transmission of human immunodeficiency virus: variability of infectivity throughout the course of infection. European Study Group on Heterosexual Transmission of HIV. Am. J. Epidemiol. 148 (1): 88-96. PMID 9663408.
- ↑ Dias, S. F., Matos, M. G. and Goncalves, A. C. (2005). Preventing HIV transmission in adolescents: an analysis of the Portuguese data from the Health Behaviour School-aged Children study and focus groups. Eur. J. Public Health 15 (3): 300-304. PMID 15941747.
- ↑ Rothenberg, R. B., Scarlett, M., del Rio, C., Reznik, D. and O'Daniels, C. (1998). Oral transmission of HIV. AIDS 12 (16): 2095-2105. PMID 9833850.
- ↑ 9.0 9.1 Laga, M., Nzila, N., Goeman, J. (1991). The interrelationship of sexually transmitted diseases and HIV infection: implications for the control of both epidemics in Africa. AIDS 5 (Suppl 1): S55-S63. PMID 1669925.
- ↑ Tovanabutra, S., Robison, V., Wongtrakul, J., Sennum, S., Suriyanon, V., Kingkeow, D., Kawichai, S., Tanan, P., Duerr, A. and Nelson, K. E. (2002). Male viral load and heterosexual transmission of HIV-1 subtype E in northern Thailand. J. Acquir. Immune. Defic. Syndr. 29 (3): 275-283. PMID 11873077.
- ↑ Sagar, M., Lavreys, L., Baeten, J. M., Richardson, B. A., Mandaliya, K., Ndinya-Achola, J. O., Kreiss, J. K., and Overbaugh, J. (2004). Identification of modifiable factors that affect the genetic diversity of the transmitted HIV-1 population. AIDS 18 (4): 615-619. PMID 15090766.
- ↑ Lavreys, L., Baeten, J. M., Martin, H. L. Jr., Overbaugh, J., Mandaliya, K., Ndinya-Achola, J., and Kreiss, J. K. (2004). Hormonal contraception and risk of HIV-1 acquisition: results of a 10-year prospective study. AIDS 18 (4): 695-697. PMID 15090778.
- ↑ Cayley, W. E. Jr. (2004). Effectiveness of condoms in reducing heterosexual transmission of HIV. Am. Fam. Physician 70 (7): 1268-1269. PMID 15508535.
- ↑ WHO (2003). Condom Facts and Figures. URL accessed on 2006-01-17.
- ↑ The Economist (2005). Too much morality, too little sense. URL accessed on 2006-01-17.
- ↑ WHO (2005). UNAIDS statement on South African trial findings regarding male circumcision and HIV. URL accessed on 2006-01-17.
- ↑ Various (2005). Repeated Use of Unsterilized Blades in Ritual Circumcision Might Contribute to HIV Spread in S. Africa, Doctors Say. Kaisernetwork.org. URL accessed on 2006-01-17.
- ↑ Fan, H. (2005). Fan, H., Conner, R. F. and Villarreal, L. P. eds AIDS: science and society, 4th, Boston, MA: Jones and Bartlett Publishers. ISBN 076370086X.
- ↑ WHO (2003). WHO, UNAIDS Reaffirm HIV as a Sexually Transmitted Disease. URL accessed on 2006-01-17.
- ↑ Physicians for Human Rights (2003). HIV Transmission in the Medical Setting: A White Paper by Physicians for Human Rights. Partners in Health. URL accessed on 2006-03-01.
- ↑ United Nations General Assembly (2001). Declaration of Commitment on HIV/AIDS Global Crisis — Global Action. URL accessed on 2006-03-01.
- ↑ WHO (2001). Blood safety....for too few. URL accessed on 2006-01-17.
- ↑ Orendi, J. M., Boer, K., van Loon, A. M., Borleffs, J. C., van Oppen, A. C., Boucher, C. A. (1998). Vertical HIV-I-transmission. I. Risk and prevention in pregnancy. Ned. Tijdschr. Geneeskd 142 (50): 2720-2724. PMID 10065235.
- ↑ Sperling, R. S., Shapirom D. E., Coombsm R. W., Todd, J. A., Herman, S. A., McSherry, G. D., O'Sullivan, M. J., Van Dyke, R. B., Jimenez, E., Rouzioux, C., Flynn, P. M. and Sullivan, J. L. (1996). Maternal viral load, zidovudine treatment, and the risk of transmission of human immunodeficiency virus type 1 from mother to infant. N. Engl. J. Med. 335 (22): 1621-1629. PMID 8965861.
- ↑ UNAIDS (2005). AIDS epidemic update, 2005. URL accessed on 2006-01-17.
|This page uses Creative Commons Licensed content from Wikipedia (view authors).|