AIDS is a disease of the human immune system caused by the human immunodeficiency virus that reduces the effectiveness of the immune system. It can be caused through sexual transmission, blood products, or perinatally from mother to child. Symptoms of AIDS can affect many body parts and include meningitis, diarrhea, tumors, retinitis, and encephalitis. Treatment consists of antiviral therapy using a mix of about three drugs and complementary alternative medicine like vitamin or mineral supplementation.