Since aHGer^83 and TS never read up and still want to act like a
noob
no choice, i copy and paste the words here
Human immunodeficiency virus (HIV) is a retrovirus that causes
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), and AIDS-associated
retrovirus (ARV).[1][2]
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 three 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 2.43.3 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.[3] A third of these deaths are occurring in sub-Saharan
Africa, retarding economic growth and increasing poverty.[4]
According to current estimates, HIV is set to infect 90 million
people in Africa, resulting in a minimum estimate of 18 million
orphans.[5] Antiretroviral treatment reduces both the mortality and
the morbidity of HIV infection, but routine access to
antiretroviral medication is not available in all
countries.[6]
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 remain healthy for many
years, with no noticeable symptoms.[7] 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).
