AIDS means deficiency of immune system, acquired during the lifetime of an individual. It is a syndrome (group of symptoms) caused by Human Immunodeficiency Virus (HIV).
Human Immuno Deficiency Virus (HIV) HIV is a member of a group of viruses, called retrovirus which have an envelope enclosing RNA genome, It spreads from one person to another only via body mulas. fluids. There is always a time lag between infection and appearance of AIDS symptoms. This time lag can be from few months to many years (mostly 5-10 years). The patient becomes so immune deficient that he/ she cannot protect himself/herself even from very common infections.