Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirusfamily) that causes 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. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid. Transmission through infected needle, unsafe (unprotected) sex, mother to baby at birth (perinatal transmission)

How the Virus affects the body : HIV 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: First, direct viral killing of infected cells; second, increased rates of apoptosis in infected cells; and third, killing of infected CD4+ T cells byCD8 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.

Prevention: Safe sex : Use of Condom Use of sterilized disposable syringes/needles Avoid sharing of toothbrush, tongue cleaner A course of antiretroviral treatment administered immediately after exposure, referred to aspost-exposure prophylaxis, reduces the risk of infection if begun as quickly as possible.

Treatment : Treatment consists of highly active antiretroviral therapy, or HAART. However ther is no premanent cure of this disease. But treatment will ensure quality and prolong the life of Patient