AIDS

AIDS is an acronym for Acquired Immunodeficiency Syndrome or Acquired Immune Deficiency Syndrome and is defined as a collection of symptoms and infections resulting from the depletion of the immune system caused by infection with HIV. Although treatments for both AIDS and HIV exist, there is no known cure. The rate of clinical disease progression varies widely between individuals and has been shown to be affected by many factors such as host susceptibility, immune function, health care, the presence of co-infections and peculiarities of the viral strain.

Transmission and infection

Patterns of HIV transmission vary in different parts of the world. In sub-Saharan Africa, which accounts for an estimated 60% of new HIV infections worldwide, controversy rages over the respective contribution of medical procedures, heterosexual sex and the bush meat trade. In the United States, sex between men (35%) and needle sharing by intravenous drug users (15%) remain prominent sources of new HIV infections. http://www.cdc.gov/hiv/stats/2003SurveillanceReport/table17.htm

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In January 2005, Anthony S. Fauci, M.D., director of NIAID said,

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"Individual risk of acquiring HIV and experiencing rapid disease progression is not uniform within populations". NIH press release Some epidemiological models suggest that over half of HIV transmission occurs in the weeks following primary HIV infection before antibodies to the virus are produced. http://www.aegis.com/pubs/rita/2002/RI020102.html http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7932084&dopt=Abstract Investigators have shown that viral loads are highest in semen and blood in the weeks before antibodies develop and estimated that the likelihood of sexual transmission from a given man to a given woman would be increased about 20-fold during primary HIV infection as compared with the same couple having the same sex act 4 months later. http://www.natap.org/2002/9retro/day27.htm Most people who are infected typically suffer from days to weeks of fever with or without muscle and joint aches, fatigue, headache, sore throat, swollen glands and sometimes rash. This "acute retroviral syndrome" is rarely diagnosed because it is difficult to distinguish from other very common ailments.

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The Centers for Disease Control (CDC) in the United States reported a cluster of HIV infections in 13 of 42 young women who reported sexual contact with the same HIV infected man in a rural county in upstate New York between February and September 1996 http://jama.ama-assn.org/cgi/content/full/282/1/20

Related Topics:
Centers for Disease Control - HIV

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The risk of oral sex has always been controversial. http://www.phac-aspc.gc.ca/publicat/epiu-aepi/epi_update_may_04/13_e.html Most of the early AIDS cases could be attributed to anal sex or vaginal sex. As the use of condoms became more widespread, there were reports of AIDS acquired by oral sex. http://www.aegis.com/pubs/bala/2000/BA000301.html Unprotected oral sex is widely understood to be less risky than unprotected vaginal sex, which in turn is less risky than unprotected anal sex.

Related Topics:
Anal sex - Vaginal sex

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Heterosexual transmission of HIV-1 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. Each 10 fold increment of seminal HIV RNA is associated with an 81% increased rate of HIV transmission. http://bmj.bmjjournals.com/cgi/content/full/324/7353/1586 During 2003 in the United States, 19% of new infections were attributed to heterosexual transmission http://www.cdc.gov/hiv/stats/2003SurveillanceReport/table17.htm

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The argument about the exact incidence of HIV transmission per act of intercourse is academic. Infectivity depends critically on social, cultural, and political factors as well as the biological activity of the agent. Whether the epidemic grows or slows depends on infectivity plus two other variables: the duration of infectiousness and the average rate at which susceptible people change sexual partners. http://bmj.bmjjournals.com/cgi/content/full/324/7353/1586

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Genetic susceptibility

CDC has released findings that genes influence susceptibility to HIV infection and progression to AIDS. HIV enters cells through an interaction with both CD4 and a chemokine receptor of the 7 Tm family. They first reviewed the role of genes in encoding chemokine receptors (CCR5 and CCR2) and chemokines (SDF-1). While CCR5 has multiple variants in its coding region, the deletion of a 32-bp segment results in a nonfunctional receptor, thus preventing HIV entry; two copies of this gene provide strong protection against HIV infection, although the protection is not absolute. This gene is found in up to 20% of Europeans but is rare in Africans and Asians; researchers and scientists believe that HIV had a similar viral shell as the bacteria which caused the black plague (1347-1350), leading to the decimation of one-third of the European population, possibly explaining why the CCR5-32 receptor gene is more prevalent in Europeans than Africans and Asians. Multiple studies of HIV-infected persons have shown that presence of one copy of this gene delays progression to the condition of AIDS by about 2 years. And it is possible that a person with the CCR5-32 receptor gene will not develop AIDS, although they will still carry HIV.

Related Topics:
Europeans - Africans - Asians - Black plague

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