Acquired Immuno Deficiency Syndrome is a disease in which the body's immune system breaks down and is unable to fight off certain infections, known as "opportunistic infections," and other illnesses that take advantage of a weakened immune system.
Human Immunodeficiency Virus (HIV) that causes AIDS. A member of a group of viruses called retroviruses, HIV infects human cells and uses the energy and nutrients provided by those cells to grow and reproduce. More details...
A person who is HIV-infected carries the virus in certain
body fluids, including blood, semen, vaginal secretions, and breast milk. The
virus can be transmitted only if such HIV-infected fluids enter the bloodstream
of another person. Direct entry can occur :-
(1) through the linings of the vagina, rectum, mouth, and the opening at the
tip of penis during intercourse;
(2) through intravenous injection with a syringe ; or
(3) through a break in the skin, such as a cut or sore.
When a person is infected with HIV, the virus enters the body and lives and multiplies primarily in the white blood cells. These are the immune cells that normally protect us from disease.
HIV infection may have symptoms such as swollen glands, extreme tiredness, sudden weight loss, night sweats, fever and skin blotches. These symptoms are common to many other less serious illnesses.
So HIV infection test has to be carried out to confirm the HIV infection. HIV infection is the progressive loss of a specific type of immune cell called T-helper or CD4 cells. As the virus grows, it damages or kills these and other cells, weakening the immune system and leaving the individual vulnerable to various opportunistic infections and other diseases.