The conditions for contracting AIDS are, first of all, that a person does not have the relevant immunity, and at present almost all people in the world are not immune to HIV, and also that one must be exposed to HIV. There is no way for a person to get AIDS if the surroundings to which he or she is exposed do not contain HIV and the people with whom he or she is in close contact do not have AIDS. There must be a route of transmission that can lead to transmission, and transmission can only occur if a person has sex with a person with AIDS, or if they share needles or syringes, and have blood contact. It is generally difficult to transmit HIV through indirect means. Because HIV has a relatively weak resistance to the external environment, if blood or body fluids containing HIV are exposed to the natural environment for a period of time, the virus will lose its pathogenicity, and even if a person comes into contact with these objects again, it will not lead to contagion.