1. Complete quarantine: The limitation of freedom of movement of such well persons or domestic animals as have been exposed to a communicable disease, for a period of time not longer than the longest usual incubation period of the disease, in such manner as to prevent effective contact with those not so exposed. 2. Modified quarantine: A selective, partial limitation of freedom of movement of persons or domestic animals, commonly on the basis of known or presumed differences in susceptibility but sometimes because of danger of disease transmission. It may be designed to meet particular situations. Examples are exclusion of children from school; or exemption of immune persons from provisions required of susceptible person, such as contact acting as food handlers; or restriction of military populations to the post or to quarters. 3. Personal surveillance: The practice of close medical or other supervision of contacts in order to promote prompt recognition of infection or illness but without restricting their movements. 4. Segregation: The separation for special consideration, control or observation of some part of a group of persons or domestic animals from the others to facilitate control of a communicable disease. Removal of susceptible children to homes of immune persons, or establishment of a sanitary boundary to protect dis infected from infected portions of a population, are examples.... quarantine