• Introduction: What is HIV/AIDS? In 1983 the virus that caused
AIDS was discovered by scientists in France and the routes of
transmission were confirmed. The virus eventually became known
as the human immunodeficiency virus (HIV). There are 2 different
types of HIV: the most common type found worldwide, and These
cells carry the CD4 antigen on their surface (CD4+ lymphocytes).
HIV recognizes the CD4 antigen and enters and infects CD4+
lymphocytes. The result is the killing of many CD4+ lymphocytes.
This slowly leads to a persistent, progressive and profound
impairment of the immune system, making an individual
susceptible to infections and conditions such as cancer. HIV is
the beginning stage of infection and can be detected by a blood
test (described in this Fact Sheet). When the immune system
becomes very affected, the illness progresses to AIDS. Blood
tests (described in this Fact Sheet), or the appearance of
certain infections, indicate that the infection has progressed
to AIDS. • HIV transmission HIV ca