Human Immunodeficiency Virus Type 1: Difference between revisions
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== Transmission == | == Transmission == | ||
HIV is primarily spread by sexual contact. Most early infections in the | HIV is primarily spread by sexual contact. Most early infections in the [[United States]] were via homosexual sex, and to a lesser extent via intravenous drug use and blood transfusions; most current infections in the world are via heterosexual contact and vertical transmission from mother to child. | ||
Mothers infected with HIV transmit the virus to their baby ''in utero'', during childbirth. Mother-to-child transmission can be significantly reduced by the proper use of antiretroviral agents. | |||
Less commonly, contact with infected blood causes HIV transmission. This can occur in health care providers (HCPs) or others exposed to infectious bodily fluids. Transmission is facilitated by breaks in the skin or direct contact with mucosal tissues, such as those found in the eyes, mouth, anus, or vagina. Early in the epidemic, blood transfusions were a significant source of HIV transmission. | Less commonly, contact with infected blood causes HIV transmission. This can occur in health care providers (HCPs) or others exposed to infectious bodily fluids. Transmission is facilitated by breaks in the skin or direct contact with mucosal tissues, such as those found in the eyes, mouth, anus, or vagina. Early in the epidemic, blood transfusions were a significant source of HIV transmission. | ||
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Early on in the epidemic, there was much confusion about the transmission of HIV. After decades of study, this has been clarified. HIV can be found in various body fluids, however its highest concentrations are found in semen, blood, and vaginal secretions. It can also be found in breast milk, but recent research <ref>The Lancet, March 30th 2007</ref> shows that exclusive breastfeeding tends to protect against HIV transmission. | Early on in the epidemic, there was much confusion about the transmission of HIV. After decades of study, this has been clarified. HIV can be found in various body fluids, however its highest concentrations are found in semen, blood, and vaginal secretions. It can also be found in breast milk, but recent research <ref>The Lancet, March 30th 2007</ref> shows that exclusive breastfeeding tends to protect against HIV transmission. | ||
===Sexual contact=== | |||
{| class="wikitable" align="right" | {| class="wikitable" align="right" | ||
|+ | |+ Risk of HIV transmission per sexual contact<ref name="urlAEGiS-AIDSWeekly: Per-Contact Risk of HIV: Odds Dont Tell Whole Story - August 9, 1999">{{cite web |url=http://www.aegis.com/pubs/aidswkly/1999/AW990801.html |title=AEGiS-AIDSWeekly: Per-Contact Risk of HIV: Odds Don't Tell Whole Story - August 9, 1999 |author= |authorlink= |coauthors= |date= |format= |work= |publisher= |pages= |language= |archiveurl= |archivedate= |quote= |accessdate=2008-07-02}}</ref> | ||
! | ! !! Risk of transmission | ||
|- | |- | ||
| | | Unprotected receptive anal sex<br>with a known seropositive partner || 0.82% | ||
|- | |- | ||
| | | Unprotected receptive anal sex<br>with a partner of unknown serostatus || 0.27% | ||
|- | |- | ||
| Unprotected insertive anal sex || 0.06% | | Unprotected insertive anal sex || 0.06% | ||
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''"The overall, unadjusted probability of HIV-1 transmission per coital act is 0·0011 in this Ugandan population, and greater infectivity of predominant HIV-1 viral subtypes is unlikely to account for the explosive HIV-1 epidemic in sub-Saharan Africa. Transmission probability per act varies greatly with the HIV-1 viral load of the HIV-1-infected partner, which suggests that interventions to reduce viral load could reduce transmission.15,28 Younger age and genital ulceration also increased the probability of transmission per act."'' THE LANCET, Volume 357: Pages 1149-1153, | ''"The overall, unadjusted probability of HIV-1 transmission per coital act is 0·0011 in this Ugandan population, and greater infectivity of predominant HIV-1 viral subtypes is unlikely to account for the explosive HIV-1 epidemic in sub-Saharan Africa. Transmission probability per act varies greatly with the HIV-1 viral load of the HIV-1-infected partner, which suggests that interventions to reduce viral load could reduce transmission.15,28 Younger age and genital ulceration also increased the probability of transmission per act."'' <ref>THE LANCET, Volume 357: Pages 1149-1153, 14 April 2001.</ref> | ||
14 April 2001 | |||
=== | ===Prevention of transmission=== | ||
{{main|Universal precautions}} | |||
The [[United States]] [[Centers for Disease Control and Prevention]] has summarized the use of [[universal precautions]] to prevent the transmission of HIV in healthcare settings. | |||
== Treatment == | == Treatment == | ||
Revision as of 02:39, 2 July 2008
| Human immunodeficiency virus | ||||||
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| Virus classification | ||||||
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HIV (Human Immunodeficiency Virus) is an infectious human retrovirus that causes AIDS (Acquired Immunodeficiency Syndrome. It is primarily a sexually transmitted disease. Currently, HIV/AIDS kills approximately 2-3 million people per year, primarily in developing countries. Currently, in the U.S. there are approximately 500,000 people infected with HIV.
Pathophysiology
After exposure, the virus invades and replicates in immune cells near the site of infection. It quickly spreads to regional lymph nodes and via the blood stream to the rest of the body. During this stage the patient may experience Acute Retroviral Syndrome, a vague flu-like illness. The patient is often asymptomatic for the first 5-10 years after infection. By that time, untreated, progression to AIDS in inevitable, except in a small subset of patients.
Clinical syndromes
Primary HIV infection
| sensitivity | specificity | |
|---|---|---|
| Fever | 88% | 50% |
| Malaise | 73% | 58% |
| Myalgia | 60% | 74% |
| Rash | 58% | 79% |
| Headache | 55% | 56% |
| Night sweats | 50% | 68% |
| Sore throat | 43% | 51% |
| Lymphadenopathy | 38% | 71% |
| Arthralgia | 28% | 87% |
| Nasal congestion | 18% | 62% |
Acquired Immune Deficiency Syndrome
Transmission
HIV is primarily spread by sexual contact. Most early infections in the United States were via homosexual sex, and to a lesser extent via intravenous drug use and blood transfusions; most current infections in the world are via heterosexual contact and vertical transmission from mother to child.
Mothers infected with HIV transmit the virus to their baby in utero, during childbirth. Mother-to-child transmission can be significantly reduced by the proper use of antiretroviral agents.
Less commonly, contact with infected blood causes HIV transmission. This can occur in health care providers (HCPs) or others exposed to infectious bodily fluids. Transmission is facilitated by breaks in the skin or direct contact with mucosal tissues, such as those found in the eyes, mouth, anus, or vagina. Early in the epidemic, blood transfusions were a significant source of HIV transmission.
Other less likely means of transmission exist, though are rare. There are no confirmed cases from contact with the saliva, sweat or tears of an infected person.
Early on in the epidemic, there was much confusion about the transmission of HIV. After decades of study, this has been clarified. HIV can be found in various body fluids, however its highest concentrations are found in semen, blood, and vaginal secretions. It can also be found in breast milk, but recent research [2] shows that exclusive breastfeeding tends to protect against HIV transmission.
Sexual contact
| Risk of transmission | |
|---|---|
| Unprotected receptive anal sex with a known seropositive partner |
0.82% |
| Unprotected receptive anal sex with a partner of unknown serostatus |
0.27% |
| Unprotected insertive anal sex | 0.06% |
| Receptive oral sex | 0.04% |
"The overall, unadjusted probability of HIV-1 transmission per coital act is 0·0011 in this Ugandan population, and greater infectivity of predominant HIV-1 viral subtypes is unlikely to account for the explosive HIV-1 epidemic in sub-Saharan Africa. Transmission probability per act varies greatly with the HIV-1 viral load of the HIV-1-infected partner, which suggests that interventions to reduce viral load could reduce transmission.15,28 Younger age and genital ulceration also increased the probability of transmission per act." [4]
Prevention of transmission
The United States Centers for Disease Control and Prevention has summarized the use of universal precautions to prevent the transmission of HIV in healthcare settings.
Treatment
Treatment issues are complicated by issues of poverty and education. In communities with adequate resources, HIV infection is treatable with Highly Active Retroviral Therapy (HAART). This therapy effectively prevents progression to AIDS in many patients, however there are many side effects to treatment, and resistance is a serious issue.
Screening
Prevention
Prevention is an issue complicated by issues of poverty and education. Sexual transmission can be effectively prevented by avoiding sexual contact (abstinence), but much of HIV tranmission takes place in marriages or other similar relationships, therefore abstinence is impractical. The most effective method is regular, proper use of latex condoms. A large percentage of those infected are unaware of their disease status, which complicates prevention. Spouses are often infected without their knowledge of their partner's status.
Occupational infection can be prevented with the use of universal precautions and by post-exposure prophylaxis.
Currently, no vaccine is available, and it is not clear if a vaccine will be available any time in the near future.
References
- ↑ Daar ES, Little S, Pitt J, et al (2001). "Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network". Ann. Intern. Med. 134 (1): 25–9. PMID 11187417. [e]
- ↑ The Lancet, March 30th 2007
- ↑ AEGiS-AIDSWeekly: Per-Contact Risk of HIV: Odds Don't Tell Whole Story - August 9, 1999. Retrieved on 2008-07-02.
- ↑ THE LANCET, Volume 357: Pages 1149-1153, 14 April 2001.
Mandell, Bennett, & Dolin: Principles and Practice of Infectious Diseases, 6th ed., Copyright © 2005 Churchill Livingstone, An Imprint of Elsevier
Guidelines for the Management of Occupational Exposures to HIV and Recommendations for Postexposure Prophylaxis. MMWR Recomm Rep. 2005;54:1-17.
www.cdc.gov
THE LANCET, Volume 357: Pages 1149-1153, 14 April 2001.
AIDSWEEKLY Plus; Monday, August 9, 1999
THE LANCET, 30 March 2007, reported in The Guardian, 30 March 2007 [1]