In epidemiology isolation refers to a procedure used in communicable disease control. It consists of a separation of cases (persons or animals) for a disease's period of communicability. The cases are isolated in a specific location and under conditions that minimize the risk of direct or indirect transmission of the infectious agents to those who may be susceptible. The American Public Health Association's Control of Communicable Diseases Manual, 17th edition, recommends "universal precautions" to prevent the transmission of blood-borne agents and strict hygienic measures such as thorough hand washing after attending to infectious cases and disinfection of articles that have been in contact with infectious cases.
The Centers for Disease Control's Guidelines for Isolation Precautions in Hospitals identifies several categories of isolation that are appropriate according to the mode of transmission of the infectious agent. Strict isolation is used for highly contagious or virulent infections in which the agent may be spread by direct contact or droplet. Procedures include segregation in a private room; use of gowns, masks, and gloves; and sometimes special ventilation. Contact isolation is used for less dangerous conditions spread by direct contact. Measures similar to strict isolation are employed, but more than one person may share a room and sometimes barrier nursing suffices. Respiratory isolation is used to prevent airborne transmission of infectious agents—it resembles contact isolation in that infectious patients may share a room. Tuberculosis isolation is used for patients known or suspected to be excreting tubercle bacilli in sputum. A private room with the door closed is required, as well as the same procedures used for contact and respiratory isolation and the use of respirator-type masks by all who enter the room. Gowns are used but gloves are unnecessary. Enteric precautions are used when the infectious agent is transmitted in feces. These precautions resemble contact isolation and include particular care in sanitary disposal of feces. Drainage/secretion precautions are used when patients are discharging purulent material, such as that from an abscess or other infected body site. A private room is not necessary, and gowns and gloves are indicated if attendants have to touch contaminated material.
JOHN M. LAST