HIV

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Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unsafe sex, contaminated needles, breast milk, and transmission from an infected mother to her baby at birth (Vertical transmission). Screening of blood products for HIV has largely eliminated transmission through blood transfusions or infected blood products in the developed world.

HIV infection in humans is now pandemic. From 1981 to 2006, AIDS killed more than 25 million people. HIV infects about 0.6 percent of the world's population. In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. A third of these deaths are occurring in sub-Saharan Africa, retarding economic growth and increasing poverty. According to current estimates, HIV is set to infect 90 million people in Africa, resulting in a minimum estimate of 18 million orphans. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.

HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.

Eventually most HIV-infected individuals develop AIDS. These individuals mostly die from opportunistic infections or malignancies associated with the progressive failure of the immune system. Without treatment, about 9 out of every 10 persons with HIV will progress to AIDS after 10–15 years. Many progress much sooner. Treatment with anti-retrovirals increases the life expectancy of people infected with HIV. Even after HIV has progressed to diagnosable AIDS, the average survival time with antiretroviral therapy (as of 2005) is estimated to be more than 5 years. Without antiretroviral therapy, death normally occurs within a year.

For more information about HIV, read the full article at Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.

News tagged with hiv

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Why Some Monkeys Don't Get AIDS

Medicine & Health / HIV & AIDS

Dec 03, 2009 | not rated yet | 0

(PhysOrg.com) -- Two studies published this month in the Journal of Clinical Investigation provide a significant advance in understanding how some species of monkeys such as sooty mangabeys and African green ...

South Africa to treat all HIV-positive babies

Medicine & Health / HIV & AIDS

Dec 01, 2009 | not rated yet | 0

(AP) -- South Africa announced ambitious new plans Tuesday for earlier and expanded treatment for HIV-positive babies and pregnant women, a change that could save hundreds of thousands of lives in the nation ...

Gay, bisexual men who have social anxiety tend to engage in risky sex

Medicine & Health / HIV & AIDS

Dec 01, 2009 | 5 / 5 (1) | 0

A Ryerson University HIV researcher has found a link between social anxiety and unsafe sexual activities among gay and bisexual men, some of whom are HIV-positive.

New study measures HIV anti-retroviral regimens' safety and efficacy

Medicine & Health / HIV & AIDS

Dec 01, 2009 | not rated yet | 0

A study in the New England Journal of Medicine released on World AIDS Day reports that viral failure, the point at which medication can no longer suppress the HIV infection, was twice as likely and happen ...