There are many signs, this may help you with your answer https://www.drugabuse.gov/publications/principles-adolescent-substance-use-disorder-treatment-resear...
Mixtures and pure substances
Muscular system because your muscles allow for your body to move
A non-sexual method can be by blood transfusion. If you take blood from someone who has HIV and use it on yourself you will get HIV. Same goes for injecting spinal fluid or any other bodily fluid. You cannot however transmit it by shaking hands with someone, or by sharing the toilet with someone or anything similar.
To apply the FITT principles to eating habits we use frequency of eating, intensity of calories, how many times they eat a day and the type of food.
FITT stands for: Frequency, Intensity, Time, Type
