1. improper hand-washing
2. Strict isolation: very careful, severe infection, strict access to patients room with gloves, gowns, masks, because patient has deadly disease.
3. protective isolation: protect them from our MO's, transplants, AIDs,
4.Precaution isolations: according to the disease, prevent cross infection
5. Quarantine: when infected person shows no signs or symptoms after being exposed, and must be kept in isolation until no longer infectious