Isolation & Quarantine
Measures in Response to a Smallpox Emergency
Additional
Transmission-Based Precautions
Additional Transmission-Based
Precautions are designed for patients documented or suspected to
be infected with highly transmissible or epidemiologically important
pathogens for which additional precautions beyond Standard Precautions
are needed to prevent or interrupt transmission in hospitals. Three
types of transmission-based precautions with examples of the biological
agents that are transmitted by this route and require these types
of precautions. All three types of Transmission-Based Precautions
should be followed for smallpox.
Airborne
Precautions
Airborne Precautions
(TB, varicella, measles, etc.) are designed to reduce the risk
of airborne transmission of infectious agents and apply to patients
known or suspected to be infected with epidemiologically important
pathogens that can be transmitted by this route.
Airborne transmission
occurs by dissemination of either airborne droplet nuclei (small-particle
residue [5 microns or smaller in size] of evaporated droplets that
can remain suspended in the air for longer periods of time) or
dust particles containing the infectious agent. Microorganisms
carried in this manner can be dispersed more widely by air currents
and may become inhaled by or deposited on a susceptible host within
the same room or over a longer distance from the source patient,
depending on environmental factors. Special air handling and ventilation
are required to prevent airborne transmission. Airborne precautions
(masks, special air handling room requirements) provides respiratory
protection for workers who must share airspace with the infectious
patient and prevents potentially contaminated air from the patient’s
room from getting to other areas of the hospital.
Droplet Precautions
Droplet Precautions
are designed to reduce risk of droplet transmission of infectious
agents. Droplet transmission involves contact of the conjunctivae
or the mucous membranes of the nose or mouth of a susceptible person
with large-particle droplets (larger than 5 microns in size) containing
microorganisms generated from a person who has a clinical disease
or who is a carrier of the microorganism.
Droplets are
generated from the source person primarily during coughing, sneezing,
or talking and during the performance of certain procedures such
as suctioning and bronchoscopy. Transmission via large-particle
droplets requires close contact between source and recipient persons,
because droplets do not remain suspended in air and generally travel
only short distances, (usually 3 ft or less). Because droplets
do not remain suspended in air, special air handling and ventilation
are not required to prevent transmission.
Contact
Precautions
Contact Precautions
are designed to reduce the risk of transmission of epidemiologically
important microorganisms by direct or indirect contact. Direct-contact
transmission involves skin-to-skin contact and physical transfer
of microorganisms to a susceptible host from and infected or colonized
person, such as occurs when personnel turn patients, bathe patients,
or perform other patient-care activities that require physical
contact. Direct-contact transmission also can occur between two
patients (e.g., by hand contact), with one serving as the source
of infectious microorganisms and the other as a susceptible host.
Indirect-contact
transmission involves contact of a susceptible host with a contaminated
object in the patient’s environment.
Contact Precautions
apply to specified patients known or suspected to be infected or
colonized (presence of microorganism in or on patient but without
clinical signs and symptoms of infection) with epidemiologically
important microorganisms that can be transmitted by direct or indirect
contact. Contact precautions (disposable protective clothing in
addition to gloves, handwashing, and splash precautions) help prevent
direct contact but also prevent the health-care provider from carrying
infectious materials to areas outside of the room.
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