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Hiv,
Aids FAQ Human immunodeficiency virus
Human
immunodeficiency virus HIV is a retrovirus that can lead to acquired immunodeficiency
syndrome AIDS, a condition in humans in which the immune system begins to
fail, leading to life-threatening opportunistic infections. Previous names
for the virus include human T-lymphotropic
virus-III (HTLV-III), lymphadenopathy-associated
virus LAV, or AIDS-associated retrovirus ARV. 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 unprotected sexual intercourse, contaminated needles, and transmission
from an infected mother to her baby at birth, or through breast milk.
Screening of blood products for HIV in the developed world has largely
eliminated transmission through blood transfusions or infected blood products
in these countries. HIV infection in
humans is now pandemic. As of January 2006, the Joint United Nations Programme on HIV/AIDS UNAIDS and the World Health
Organization WHO estimate that AIDS has killed more than 25 million people
since it was first recognized on December 1, 1981, making it one of the most
destructive pandemics in recorded history. In 2005 alone, AIDS claimed an
estimated 2.4–3.3 million lives, of which more than 570,000 were children. It
is estimated that about 0.6% of the world's living population is infected
with HIV. A third of these deaths are occurring in sub-Saharan 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. If untreated, eventually most HIV-infected
individuals develop AIDS (Acquired Immunodeficiency Syndrome) and die;
however about one in ten remains healthy for many years, with no noticeable
symptoms. Treatment with anti-retrovirals, where
available, increases the life expectancy of people infected with HIV. It is
hoped that current and future treatments may allow HIV-infected individuals
to achieve a life expectancy approaching that of the general public see
Treatment. Aids Acquired
immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or
Aids) is a collection of symptoms and infections resulting from the specific
damage to the immune system caused by the human immunodeficiency virus (HIV)
in humans,[1] and similar viruses in other species (SIV, FIV, etc.). The late
stage of the condition leaves individuals susceptible to opportunistic
infections and tumors. Although treatments for AIDS and HIV exist to
decelerate the virus' progression, there is currently no known cure. HIV, et
al., are transmitted through direct contact of a mucous membrane or the
bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal
fluid, preseminal fluid, and breast milk.[2][3] This transmission can come in the form of anal,
vaginal or oral sex, blood transfusion, contaminated hypodermic needles,
exchange between mother and baby during pregnancy, childbirth, or
breastfeeding, or other exposure to one of the above bodily fluids. Most
researchers believe that HIV originated in sub-Saharan Africa during the
twentieth century;[4] it is now a pandemic, with an
estimated 33.2 million people now living with the disease worldwide.[5] As of
January 2006, the Joint United Nations Programme on
HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS
has killed more than 25 million people since it was first recognized on June
5, 1981, making it one of the most destructive epidemics in recorded history.
In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more
than 570,000 were children.[6] A third of these
deaths are occurring in sub-Saharan |
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