AIDS

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AIDS	Antibodies	Canker sore (aphthous ulcer)	Dermatitis, seborrheic - close-up
Dermatitis, seborrheic on the face	Herpes zoster (shingles), disseminated	Histoplasmosis, disseminated in HIV patient	HIV
Kaposi's sarcoma - close-up	Kaposi's sarcoma - lesion on the foot	Kaposi's sarcoma on the back	Kaposi's sarcoma on the thigh
Kaposi's sarcoma - perianal	Molluscum contagiosum on the face	Molluscum on the chest	Mycobacterium marinum infection on the hand
Primary HIV infection	STDs and ecological niches	Tuberculosis in the lung

AIDS (Acquired Immune Deficiency Syndrome) is the final and most serious stage of HIV disease, which causes severe damage to the immune system.

According to the Centers for Disease Control and Prevention, AIDS begins when a person with HIV infection has a CD4 cell count below 200. CD4 cells are also called "T-cells" or "helper cells"; they are a type of immune cell. AIDS is also defined by numerous opportunistic infections and cancers that occur in the presence of HIV infection.

Acquired immune deficiency syndrome

AIDS is the fifth leading cause of death among persons between ages 25 and 44 in the United States, down from number one in 1995. About 25 million people worldwide have died from this infection since the start of the epidemic, and 40.3 million people are currently living with HIV/AIDS globally

Human immunodeficiency virus (HIV) causes AIDS. The virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening infections and cancers.

Common bacteria, yeast, parasites, and viruses that ordinarily do not cause serious disease in people with healthy immune systems can cause fatal illnesses in people with AIDS.

HIV has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk generally transmit infection to others.

Transmission of the virus occurs:

• Through sexual contact -- including oral, vaginal, and anal sex
• Through blood -- via blood transfusions (now extremely rare in the U.S) or needle sharing
• From mother to child -- a pregnant woman can transmit the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby in her milk

Other transmission methods are rare and include accidental needle injury, artificial insemination with donated semen, and organ transplants.

HIV infection is not spread by casual contact such as hugging, by touching items previously touched by a person infected with the virus, during participation in sports, or by mosquitoes.