<P> In health care facilities, isolation represents one of several measures that can be taken to implement infection control: the prevention of contagious diseases from being spread 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 others . 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". </P> <P> Isolation is most commonly used when a patient is known to have a contagious (transmissible 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 . </P> <P> Isolation is defined as the voluntary or compulsory separation and confinement of those known or suspected to be infected with a contagious disease agent (whether ill or not) to prevent further infections . (In this form of isolation, transmission - based precautions are imposed .) In contrast, quarantine is the compulsory separation and confinement, with restriction of movement, of healthy individuals or groups who have potentially been exposed to an agent 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 . </P> <P> Universal precautions refer to the practice, in medicine, of avoiding contact with patients' bodily fluids, by means of the wearing of nonporous articles such as medical gloves, goggles, and face shields . The practice was widely introduced in 1985--88 . In 1987, the practice of universal precautions was adjusted by a set of rules known as body substance isolation . In 1996, both practices were replaced by the latest approach known as standard precautions . Use of personal protective equipment is now recommended in all health settings . </P>

How many healthcare workers are required for most procedures in an isolation unit