Human Immunodeficiency Virus Type 1: Difference between revisions
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'''Human Immunodeficiency Virus''' (''HIV'') is an infectious human [[retrovirus]] that causes [[Acquired Immunodeficiency Syndrome]] (AIDS). 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. | '''Human Immunodeficiency Virus''' (''HIV'') is an infectious human [[retrovirus]] that causes [[Acquired Immunodeficiency Syndrome]] (AIDS). 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. | ||
==History== | |||
The association between [[opportunistic infection]]s such as ''[[pneumocystis carinii]]'' pneumonia and [[homsexuality]] or [[intravenous substance abuse]] was first reported in 1981.<ref name="pmid6975437">{{cite journal| author=Masur H, Michelis MA, Greene JB, Onorato I, Stouwe RA, Holzman RS et al.| title=An outbreak of community-acquired Pneumocystis carinii pneumonia: initial manifestation of cellular immune dysfunction. | journal=N Engl J Med | year= 1981 | volume= 305 | issue= 24 | pages= 1431-8 | pmid=6975437 | |||
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=6975437 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref><ref name="pmid6272109">{{cite journal| author=Gottlieb MS, Schroff R, Schanker HM, Weisman JD, Fan PT, Wolf RA et al.| title=Pneumocystis carinii pneumonia and mucosal candidiasis in previously healthy homosexual men: evidence of a new acquired cellular immunodeficiency. | journal=N Engl J Med | year= 1981 | volume= 305 | issue= 24 | pages= 1425-31 | pmid=6272109 | |||
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=6272109 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref> According to the [[United States]] [[National Library of Medicine]], "prior to 1986, HIV was called human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). From 1986-1990, it was an official species called HIV. Since 1991, HIV was no longer considered an official species name; the two species were designated HIV-1 and HIV-2."<ref>{{MeSH}}</ref> | |||
== Pathophysiology == | == Pathophysiology == | ||
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==Clinical syndromes== | ==Clinical syndromes== | ||
===Primary HIV infection=== | ===Primary HIV infection=== | ||
{| class="wikitable sortable" | {| class="wikitable sortable" align="right" | ||
|+ History and physical findings for primary HIV infection<ref name="pmid11187417">{{cite journal |author=Daar ES, Little S, Pitt J, ''et al'' |title=Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network |journal=Ann. Intern. Med. |volume=134 |issue=1 |pages=25–9 |year=2001 |pmid=11187417 |doi=}}</ref> | |+ History and [[physical examination]] findings for primary HIV infection<ref name="pmid11187417">{{cite journal |author=Daar ES, Little S, Pitt J, ''et al'' |title=Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network |journal=Ann. Intern. Med. |volume=134 |issue=1 |pages=25–9 |year=2001 |pmid=11187417 |doi=}}</ref> | ||
! !! [[sensitivity (tests)|sensitivity]]!! [[specificity (tests)|specificity]] | ! !! [[sensitivity (tests)|sensitivity]]!! [[specificity (tests)|specificity]] | ||
|- | |- |
Revision as of 06:37, 17 October 2009
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Human immunodeficiency virus | ||||||
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Virus classification | ||||||
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Human Immunodeficiency Virus (HIV) is an infectious human retrovirus that causes Acquired Immunodeficiency Syndrome (AIDS). 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.
History
The association between opportunistic infections such as pneumocystis carinii pneumonia and homsexuality or intravenous substance abuse was first reported in 1981.[1][2] According to the United States National Library of Medicine, "prior to 1986, HIV was called human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). From 1986-1990, it was an official species called HIV. Since 1991, HIV was no longer considered an official species name; the two species were designated HIV-1 and HIV-2."[3]
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.
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; however exclusive breastfeeding tends to protect against HIV transmission.[5]
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.
Blood exposure
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.
Sexual contact
Risk of transmission per act | |
---|---|
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% |
A cohort study of monogamous, heterosexual, HIV-1-discordant couples in Uganda found that the "overall, unadjusted probability of HIV-1 transmission per coital act is 0·0011...higher viral load and genital ulceration are the main determinants of HIV-1 transmission."[7]
Diagnosis
HIV Test
Other tests
Total lymphocyte count
In predicting a CD4+ T-cell of less than 200:[8]
- Total lymphocyte count of more than 2000 has sensitivity or 95%
- Total lymphocyte count of less than 1200 has specificity of 95%
Management
Clinical practice guidelines guide management.[9] The following should be done when health care is started:[9]
- CD4 cell count and percentage
- Genotype determination to detect resistance
- Glucose‐6‐phosphate dehydrogenase in certain ethnic groups
- "Cytomegalovirus (CMV) screening for patients at low risk for CMV infection; varicella zoster virus screening for those who deny history of chickenpox or shingles; HSV‐2 screening is recommended by some expert"
- "Hepatitis B surface antigen, antibody to hepatitis B surface antigen or to hepatitis B core antigen, antibody to hepatitis C virus, total hepatitis A antibody"
- Screening for syphilis; Serologic testing for Toxoplasma gondii
- Tuberculosis screening
In addition:
- HLA B*5701 should be tested before using abacavir
- Tropism testing for X4‐ or dual/mixed‐tropic virus before using the CCR5 receptor antagonist maraviroc
Treatment with antiretroviral therapy (ART) is complicated by issues of poverty and education. In communities with adequate resources, HIV infection is treatable with highly active antiretroviral 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.
When to start treatment
Clinical practice guidelines based recommend to treat if ony of the following are true:[10]
- CD4 cell count is less than 350/microL.
- Among patient with CD4 cell count > 350/microL, treat if
- high plasma viral load (eg, >100,000 copies/mL)
- rapidly declining CD4 cell count (>100/microL per year)
- active hepatitis B or C virus infection
- cardiovascular disease risk
- HIV-associated nephropathy
A meta-analysis of cohort studies concludes "350 cells per microL should be the minimum threshold."[11] A more recent cohort study suggests treatment should begin before CD4 cell count drops to 500/microL.[12]
Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
- Abacavir (ABC)
- Didanosine (ddI)
- Emtricitabine (FTC)
- Lamivudine (3TC)
- Stavudine (d4T)
- Zalcitabine (ddC)
- Zidovudine (AZT)
Nonnucleoside reverse transcriptase inhibitors (NNRTIs)
- Delavirdine
- Efavirenz (EFV)
- Nevirapine
Protease inhibitors (PIs)
- Atazanavir
- Darunavir
- Fosamprenavir
- Indinavir
- Nelfinavir
- Ritonavir
- Saquinavir
- Tipranavir
- Lopinavir/ritonavir combination
Inhibitors of cell entry
- Enfuvirtide
Human chemokine receptor 5 (CCR5) blockers bind to the human CCR5 receptor which prevents R5 tropic HIV from entering cells.
- Maraviroc[13]
Prognosis
A multinational cohort study has found that since the introduction of highly active antiretroviral therapy, "mortality rates for HIV-infected persons have become much closer to general mortality rates." [14]
A second, industry-funded, multinational cohort study has found that with combination treatment, "the average number of years remaining to be lived at age 20 years was about two-thirds of that in the general population in these countries."[15]
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.
Prevention in health care settings
The United States Centers for Disease Control and Prevention has summarized the use of universal precautions to prevent the transmission of HIV in health care settings.
In addition, the Centers for Disease Control and Prevention has published guidelines on preventing transmission by use of postexposure prophylaxis.[16]
References
- ↑ Masur H, Michelis MA, Greene JB, Onorato I, Stouwe RA, Holzman RS et al. (1981). "An outbreak of community-acquired Pneumocystis carinii pneumonia: initial manifestation of cellular immune dysfunction.". N Engl J Med 305 (24): 1431-8. PMID 6975437.
- ↑ Gottlieb MS, Schroff R, Schanker HM, Weisman JD, Fan PT, Wolf RA et al. (1981). "Pneumocystis carinii pneumonia and mucosal candidiasis in previously healthy homosexual men: evidence of a new acquired cellular immunodeficiency.". N Engl J Med 305 (24): 1425-31. PMID 6272109.
- ↑ Anonymous (2024), Human Immunodeficiency Virus Type 1 (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ 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]
- ↑ Coovadia HM, Rollins NC, Bland RM, et al (March 2007). "Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study". Lancet 369 (9567): 1107–16. DOI:10.1016/S0140-6736(07)60283-9. PMID 17398310. Research Blogging.
- ↑ AEGiS-AIDSWeekly: Per-Contact Risk of HIV: Odds Don't Tell Whole Story - August 9, 1999. Retrieved on 2008-07-02.
- ↑ Gray RH, Wawer MJ, Brookmeyer R, et al (April 2001). "Probability of HIV-1 transmission per coital act in monogamous, heterosexual, HIV-1-discordant couples in Rakai, Uganda". Lancet 357 (9263): 1149–53. DOI:10.1016/S0140-6736(00)04331-2. PMID 11323041. Research Blogging.
- ↑ Blatt SP, Lucey CR, Butzin CA, Hendrix CW, Lucey DR (1993). "Total lymphocyte count as a predictor of absolute CD4+ count and CD4+ percentage in HIV-infected persons.". JAMA 269 (5): 622-6. PMID 8093628.
- ↑ 9.0 9.1 Aberg JA, Kaplan JE, Libman H, Emmanuel P, Anderson JR, Stone VE et al. (2009). "Primary care guidelines for the management of persons infected with human immunodeficiency virus: 2009 update by the HIV medicine association of the infectious diseases society of America.". Clin Infect Dis 49 (5): 651-81. DOI:10.1086/605292. PMID 19640227. Research Blogging.
- ↑ Hammer SM, Eron JJ, Reiss P, et al (August 2008). "Antiretroviral treatment of adult HIV infection: 2008 recommendations of the International AIDS Society-USA panel". JAMA 300 (5): 555–70. DOI:10.1001/jama.300.5.555. PMID 18677028. Research Blogging.
- ↑ (April 2009) "Timing of initiation of antiretroviral therapy in AIDS-free HIV-1-infected patients: a collaborative analysis of 18 HIV cohort studies". Lancet 373 (9672): 1352–63. DOI:10.1016/S0140-6736(09)60612-7. PMID 19361855. Research Blogging. JournalWatch
- ↑ Kitahata MM, Gange SJ, Abraham AG, et al (April 2009). "Effect of Early versus Deferred Antiretroviral Therapy for HIV on Survival". N. Engl. J. Med.. DOI:10.1056/NEJMoa0807252. PMID 19339714. Research Blogging. Physician's First Watch
- ↑ Gulick, Roy M.; Jacob Lalezari, James Goodrich, Nathan Clumeck, Edwin DeJesus, Andrzej Horban, Jeffrey Nadler, Bonaventura Clotet, Anders Karlsson, Michael Wohlfeiler, John B. Montana, Mary McHale, John Sullivan, Caroline Ridgway, Steve Felstead, Michael W. Dunne, Elna van der Ryst, Howard Mayer, the MOTIVATE Study Teams (2008-10-02). "Maraviroc for Previously Treated Patients with R5 HIV-1 Infection". N Engl J Med 359 (14): 1429-1441. DOI:10.1056/NEJMoa0803152. Retrieved on 2008-10-02. Research Blogging.
- ↑ Bhaskaran, Krishnan; Osamah Hamouda, Mette Sannes, Faroudy Boufassa, Anne M. Johnson, Paul C. Lambert, Kholoud Porter, for the CASCADE Collaboration (2008-07-02). "Changes in the Risk of Death After HIV Seroconversion Compared With Mortality in the General Population". JAMA 300 (1): 51-59. DOI:10.1001/jama.300.1.51. Retrieved on 2008-07-02. Research Blogging.
- ↑ The Antiretroviral Therapy Cohort Collaboration (2008). Life expectancy of individuals on combination antiretroviral therapy in high-income countries: a collaborative analysis of 14 cohort studies. Lancet DOI:10.1016/S0140-6736(08)61113-7
- ↑ Panlilio AL, Cardo DM, Grohskopf LA, Heneine W, Ross CS (September 2005). "Updated U.S. Public Health Service guidelines for the management of occupational exposures to HIV and recommendations for postexposure prophylaxis". MMWR Recomm Rep 54 (RR-9): 1–17. PMID 16195697. [e]