Changes

==History==

==History==

In 1983, Barre-Sinoussi, Chermann, and Montagnier (at the Pasteur Institute in Paris) isolated a retrovirus from lymph node cells of a patient with lymphadenopathy; accordingly, this virus was designated lymphadenopathy-associated virus (LAV).  Lymphadenopathy-associated virus was shown to replicate and cause cytopathology in cultures of human peripheral blood lymphocytes.  A year after the report on LAV, Gallo and co-workers (at the National Institutes of Health, Bethesda, MD) described the isolation of a cytopathic T-lymphotropic retrovirus, designated human T-lymphotropic virus type III (HTLV-III), from peripheral blood lymphocytes of patients with acquired immunodeficiency syndrome (AIDS)<ref>Gallo RC, Salahuddin SZ, Propovic M, et al. Frequent detection and isolation of cytopathic retroviruses (HTLV-II) from patients with AIDS and at risk for AIDS. ''Science'' 1984;224:500-503.</ref>  Although this HTLV-III isolate was later shown to be a contaminant of virus from the Pasteur Institute<ref>Bryant ML, Yamamoti J, Luciw P, Munn R, Marx P, Higgins J, Pedersen N, Levine A, gardner MB, Molecular comparison of retroviruses associated with human and simian AIDS. ''Hematol Oncol'' 1985;3:187-197.</ref><ref>Chang SYP, Bowman BH, Weiss JB, Garcia RE, White TJ. The origin of HIV-1 isolate HTLV-IIIB. ''Nature'' 1993;363:466-469.</ref><ref>Wain-Hobson S, Vartanian JP, Henry M, Chenciner N, Cheynier R, Delassus S, Martins LP, Sala M, Nugeyre MT, Guetard D. LAV revisited: origins of the early HIV-1 isolates from Institut Pasteur. ''Science'' 1991;252:961-965.</ref>, subsequent isolates of HTLV-III were unique<ref>Hahn BH, Gonda MA, Shaw GM, Popovic M, Hoxie JA, Gallo RC, Wong-Staal F. Genomic diversity of the acquired immune deficiency syndrome virus HTLV-III: different viruses exhibit greatest divergence in their envelope genes.  Proc Natl Acad Sci USA 1985;82:4813-4817.</ref>. Also, in 1984, Levy and co-workers (at the University of California, San Francisco) cultured an AIDS-associated retrovirus (ARV) from peripheral blood mononuclear cells of an AIDS patient<ref>Levy JA, Hoffman AD, Kramer SM, Landis JA, Shimabukuro JM, Oshiro LS. Isolation of lymphocytopathic retroviruses from San Francisco patients with AIDS. Science 1984;225:840-842</ref>. Molecular cloning and sequence analysis revealed that the genomes of LAV and HTLV-III were nearly identical, exhibiting 1% to 2% divergence.  In contrast, the genome of the ARV-2 isolate displayed up to 15% differences in nucleotide sequences in pairwise alignments with the genomes of either LAV or HTLV-III.  Electron microscopy demonstrated that these viruses from AIDS patients were morphologically similar to members of the lentivirus genus of the family ''Retroviridae''.  Furthermore, comparison of genome sequences also supported the notion that the human retroviruses associated with AIDS were related, albeit distantly, to lentiviruses of other animals.

In 1983, Barre-Sinoussi, Chermann, and Montagnier (at the Pasteur Institute in Paris) isolated a retrovirus from lymph node cells of a patient with lymphadenopathy; accordingly, this virus was designated lymphadenopathy-associated virus (LAV).  Lymphadenopathy-associated virus was shown to replicate and cause cytopathology in cultures of human peripheral blood lymphocytes.  A year after the report on LAV, Gallo and co-workers (at the National Institutes of Health, Bethesda, MD) described the isolation of a cytopathic T-lymphotropic retrovirus, designated human T-lymphotropic virus type III (HTLV-III), from peripheral blood lymphocytes of patients with acquired immunodeficiency syndrome (AIDS)<ref>Gallo RC, Salahuddin SZ, Propovic M, et al. Frequent detection and isolation of cytopathic retroviruses (HTLV-II) from patients with AIDS and at risk for AIDS. ''Science'' 1984;224:500-503.</ref>  Although this HTLV-III isolate was later shown to be a contaminant of virus from the Pasteur Institute,<ref>Bryant ML, Yamamoti J, Luciw P, Munn R, Marx P, Higgins J, Pedersen N, Levine A, gardner MB, Molecular comparison of retroviruses associated with human and simian AIDS. ''Hematol Oncol'' 1985;3:187-197.</ref><ref>Chang SYP, Bowman BH, Weiss JB, Garcia RE, White TJ. The origin of HIV-1 isolate HTLV-IIIB. ''Nature'' 1993;363:466-469.</ref><ref>Wain-Hobson S, Vartanian JP, Henry M, Chenciner N, Cheynier R, Delassus S, Martins LP, Sala M, Nugeyre MT, Guetard D. LAV revisited: origins of the early HIV-1 isolates from Institut Pasteur. ''Science'' 1991;252:961-965.</ref> subsequent isolates of HTLV-III were unique.<ref>Hahn BH, Gonda MA, Shaw GM, Popovic M, Hoxie JA, Gallo RC, Wong-Staal F. Genomic diversity of the acquired immune deficiency syndrome virus HTLV-III: different viruses exhibit greatest divergence in their envelope genes.  Proc Natl Acad Sci USA 1985;82:4813-4817.</ref>  Also, in 1984, Levy and co-workers (at the University of California, San Francisco) cultured an AIDS-associated retrovirus (ARV) from peripheral blood mononuclear cells of an AIDS patient.<ref>Levy JA, Hoffman AD, Kramer SM, Landis JA, Shimabukuro JM, Oshiro LS. Isolation of lymphocytopathic retroviruses from San Francisco patients with AIDS. Science 1984;225:840-842</ref>  Molecular cloning and sequence analysis revealed that the genomes of LAV and HTLV-III were nearly identical, exhibiting 1% to 2% divergence.  In contrast, the genome of the ARV-2 isolate displayed up to 15% differences in nucleotide sequences in pairwise alignments with the genomes of either LAV or HTLV-III.  Electron microscopy demonstrated that these viruses from AIDS patients were morphologically similar to members of the lentivirus genus of the family ''Retroviridae''.  Furthermore, comparison of genome sequences also supported the notion that the human retroviruses associated with AIDS were related, albeit distantly, to lentiviruses of other animals.

== Transmission ==

== 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.  

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.  

As summarized by the [[Centers for Disease Prevention and Control]]<ref>www.cdc.gov</ref>:

As summarized by the [[Centers for Disease Prevention and Control]]:<ref>http://www.cdc.gov</ref>

<blockquote>An exposure that might place HCP at risk for HIV infection is defined as a percutaneous injury (e.g., a needlestick or cut with a sharp object) or contact of mucous membrane or nonintact skin (e.g., exposed skin that is chapped, abraded, or afflicted with dermatitis) with blood, tissue, or other body fluids that are potentially infectious. In addition to blood and visibly bloody body fluids, semen and vaginal secretions also are considered potentially infectious. Although semen and vaginal secretions have been implicated in the sexual transmission of HIV, they have not been implicated in occupational transmission from patients to HCP.</blockquote>

<blockquote>An exposure that might place HCP at risk for HIV infection is defined as a percutaneous injury (e.g., a needlestick or cut with a sharp object) or contact of mucous membrane or nonintact skin (e.g., exposed skin that is chapped, abraded, or afflicted with dermatitis) with blood, tissue, or other body fluids that are potentially infectious. In addition to blood and visibly bloody body fluids, semen and vaginal secretions also are considered potentially infectious. Although semen and vaginal secretions have been implicated in the sexual transmission of HIV, they have not been implicated in occupational transmission from patients to HCP.</blockquote>

== Infection ==

== Infection ==

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 [[Asympotomatic carrier|asymptomatic]] for the first 5-10 years after infection.  By that time, untreated, progression to AIDS is inevitable, except in a small subset of patients.

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 [[Asympotomatic carrier|asymptomatic]] for the first 5–10 years after infection.  By that time, untreated, progression to AIDS is inevitable, except in a small subset of patients.

== Treatment ==

== Treatment ==

Prevention is an issue complicated by issues of poverty and education.  Sexual transmission can be effectively prevented by avoiding sexual contact ([[abstinence]]), or by 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.   

Prevention is an issue complicated by issues of poverty and education.  Sexual transmission can be effectively prevented by avoiding sexual contact ([[abstinence]]), or by 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<ref>Guidelines for the Management of Occupational Exposures to HIV and Recommendations for Postexposure Prophylaxis. MMWR Recomm Rep. 2005;54:1-17.</ref>.

Occupational infection can be prevented with the use of universal precautions and by post-exposure prophylaxis.<ref>Guidelines for the Management of Occupational Exposures to HIV and Recommendations for Postexposure Prophylaxis. MMWR Recomm Rep. 2005;54:1-17.</ref>

Currently, no [[vaccine]] is available, and it is not clear if a vaccine will be available any time in the near future.

Currently, no [[vaccine]] is available, and it is not clear if a vaccine will be available any time in the near future.

THE LANCET, 30 March 2007, reported in ''The Guardian'', 30 March 2007 [http://www.guardian.co.uk/aids/story/0,,2046416,00.html]  

THE LANCET, 30 March 2007, reported in ''The Guardian'', 30 March 2007 [http://www.guardian.co.uk/aids/story/0,,2046416,00.html]  

[[Category: Medicine]]

[[Category:Medicine]]

[[Category:Diseases]]

[[Category:Diseases]]

[[Category: Viruses]]

[[Category:Viruses]]

[[Category:Sexually Transmitted Disease]]

[[Category:Sexually Transmitted Disease]]