CHAPTER ONE
INTRODUCTION
The human immune deficiency viruses (HIV) are two species of lentivirus (a sub group of retrovirus) that causes HIV infection and over time acquired immune deficiency syndrome (AIDS). AIDS is a condition in humans in which progressive failure of the immune system allow life threatening opportunistic infection and cancers to thrive.(UNAIDS and WHO, 2007). Two types of HIV have been characterized: HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and termed both Lymphadenopathy associated virus (LAV) and human T- lymphotropic virus 3 (HTLV-III). HIV-1 is more virulent and more infective than HIV-2, (Glibert et al, 2003) and the cause of the majority of HIV infections globally. The lower infectivity of HIV-2, compared to HIV-1, implies that fewer of those exposed to HIV-2 will be infected per exposure. Due to its relatively poor capacity for transmission HIV-2 is largely confined to West African (Reeves and Doms, 2002).
In must cases, HIV is a sexually transmitted infection and occurs by contacts with or transfer of blood, pre ejaculate Semen and vaginal fluid. Research has shown (for both same sex and opposite- sex couples) that HIV untransmissable through condomless sexual intercourse if the Hiv positive partner has a consistently undetectable viral load. (Rodger et al, 2009; Eisinger et al, 2019) contaminated blood transfusions, hypodermic needle and from mother to child during pregnancy, delivery or breastfeeding (Rom and Markowitz, 2007). Some body fluids, such as saliva and tears do not transmit HIV (CDC, 2006).