Pathogen that causes AIDS to human immunodeficiency virus (HIV), it is a retrovirus. This virus reverse transcriptase, RNA transcription of their DNA. HIV is a RNA virus, more cylindrical or oval-shaped, 100 ~ 120nm in diameter virus particles, sensitive to heat at 56 ℃ 30 minutes can be killed. Sensitive to a variety of disinfectants, such as ethanol, bleach, 0.2% to 0.5% sodium hypochlorite, formaldehyde solution, are good for their inactivation. HIV is a kind of addicted to T cells and perineural cells, the virus invades the human body to selectively attack on T helper cells, brain cells, spinal cord cells and peripheral nerve cells. When a large number of HIV within the growth and reproduction in the TH to TH a large number of damage, defects in cell-mediated immunity occurred, self-stability, and immune surveillance function of loss, not only a series of protozoa, worms, fungi, bacteria and viral pathogens infections and other conditions, but also a rare malignant tumor may occur, eventually leading to death.