In health care facilities, isolation represents one of several measures that can be taken to implement in infection control: the prevention of communicable diseases from being transmitted from a patient to other patients, health care workers, and visitors, or from outsiders to a particular patient (reverse isolation). Various forms of isolation exist, in some of which contact procedures are modified, and others in which the patient is kept away from all other people. In a system devised, and periodically revised, by the U.S. Centers for Disease Control and Prevention (CDC), various levels of patient isolation comprise application of one or more formally described "precaution".
Isolation is most commonly used when a patient is known to have a contagious (transmissible from person-to-person) viral or bacterial illness. Special equipment is used in the management of patients in the various forms of isolation. These most commonly include items of personal protective equipment (gowns, masks, and gloves) and engineering controls (positive pressure rooms, negative pressure rooms, laminar air flow equipment, and various mechanical and structural barriers). Dedicated isolation wards may be pre-built into hospitals, or isolation units may be temporarily designated in facilities in the midst of an epidemic emergency.
Isolation should not be confused with quarantine or biocontainment. Quarantine is the compulsory separation and confinement, with restriction of movement, of individuals or groups who have potentially been exposed to an infectious microorganism, to prevent further infections, should infection occur. Biocontainment refers to laboratory biosafety in microbiology laboratories in which the physical containment (BSL-3, BSL-4) of highly pathogenic organisms is accomplished through built-in engineering controls.When isolation is applied to a community or a geographic area it is known as a cordon sanitaire. Reverse isolation of a community, to protect its inhabitants from coming into contact with an infectious disease, is known as protective sequestration.