HIV AIDS

What is Hiv & Aids

The human immunodeficiency virus ( HIV ) is a
lentivirus (a subgroup of retrovirus ) that causes the
acquired immunodeficiency syndrome (AIDS), [1][2] a
condition in humans in which progressive failure of
the immune system allows life-threatening
opportunistic infections and cancers to thrive.
Without treatment, average survival time after
infection with HIV is estimated to be 9 to 11 years,
depending on the HIV subtype. [3] 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.

HIV infects vital cells in the human immune system
such as helper T cells (specifically CD4 + T cells),
macrophages, and dendritic cells.[4] HIV infection
leads to low levels of CD4 + T cells through a number
of mechanisms, including apoptosis of uninfected
bystander cells, [5] direct viral killing of infected cells,
and killing of infected CD4 + T cells by CD8 cytotoxic
lymphocytes that recognize infected cells. [6] 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.