Immunodeficiency is another word that refers to the immune system. It means that a person's immune system is not strong enough to work correctly and is lacking the ability to fight off disease-causing organisms that normally it wouldn't destroy easily. Syndrome means a group of conditions or symptoms that show that something is wrong. HIV stands for Human Immunodeficiency virus . A virus is a very small organism that invades a person's body and causes disease.
Different viruses cause different illnesses.
AIDS is a result of an infection. HIV invades and destroys T-lymocytes and macrophages, two types of white blood cells that are very important in fighting off infections. A virus is much smaller than a blood cell, so HIV is able to enter T-cells and macrophages and love inside them. The T-cell count falls lower and lower as the AIDS virus destroys more and more healthy cells. Because the T4-cell is an important part of the immune system the body's ability to fight off infections is decreased.