As a public health measure, quarantine has come to mean the restriction of
disease carriers to an environment where their contact with outsiders is limited.
Quarantine was widely used until the 1950s. For self-limited diseases such as
measles, the infected person was required to stay home and not have visitors.
For diseases such as infectious tuberculosis before antitubercular agents were
available, the quarantine might be at a sanitarium with other tuberculosis
Isolation, a special case of quarantine, is almost always used in an institutional
setting. It may be reverse isolation, to protect the person being isolated. The
most famous reverse isolation case was the “bubble baby,” the child who was
raised in an isolation chamber because he did not have a functioning immune
system. The medical and psychological sequellae of indefinite length long-term
protective isolation were sufficiently daunting to discourage its further use.
Nevertheless, it is used routinely for short, controlled periods for patients
undergoing certain types of chemotherapy and organ transplantation.
Isolation is used for diseases that are transmitted through casual contact or
respiratory transmission. Strict isolation is used for highly infectious agents that
may travel long distances through the air or be caught from cutaneous contact
with sores or secretions. Strict isolation requires restriction to a private room
with controlled air flow. Persons entering the room must wear gowns, gloves,
and respirators capable of filtering out micron-level particles. Respiratory
isolation is used for diseases such as tuberculosis that are spread through the
inspiration of infected particles but have only limited spread through contact
with wounds or secretions. Respiratory isolation requires the same precautions
as strict isolation but without the extensive gowning and gloving. Contact
isolation is for diseases that spread by direct contact and limited droplet
spread. It requires personal protective measures but not a controlled air
supply. [Coleman D. The when and how of isolation.
Strict and respiratory isolation must be meticulously maintained to be effective.
Patients may not leave the room without supervision to ensure that they do
not remove their respirators. Staff must never break isolation, and visitors
must be carefully monitored. The patient rooms must be at negative pressure
to doors and hallways. The room air must be exhausted outside, preferably
through high- efficiency air particulate air filters. Ultraviolet lights may also be
used to reduce the spread of infectious particles. All treatment rooms must
meet these isolation standards, including the control of personnel entering and
leaving the room. [Drug- resistant TB outbreak highlights need for screening.
AIDS Alert. 1991;6:96.] The CDC and the military maintain a few very high-
level biohazard isolation and medical facilities for potential cases of unknown
new agents or highly dangerous diseases such as the Marburg or Ebola viruses.