Acquired immunodeficiency syndrome (AIDS) is a caused by human immunodeficiency virus (HIV). It is communicable disease affecting immune system that is characterized by reduction in the numbers of lymphocytes especially CD4-bearing helper T-cells rendering the persons highly vulnerable to life-threatening infections. HIV is commonly transmitted by sexual intercourse, HIV infected blood transfusion, sharing of syringes by illicit intravenous drug users and from pregnant mothers to fetuses.