Smallpox
Outbreak Control Activities and Strategies
Isolation
and Quarantine (22:V1:60)
Smallpox
is transmitted by respiratory droplets and through contact with
secretions from smallpox lesions. Droplets can spread about 6 feet
and can remain viable for a few hours. Isolation of smallpox patients
should involve infection control measures to prevent:
- The sharing
of air between a smallpox patient and a person susceptible to
disease (respiratory isolation and precautions).
- Transmission
of the virus to the healthcare provider by direct contact or
to others from a healthcare provider with contaminated clothing
(contact isolation and precautions).
- Others from
coming into contact with infectious materials from the patient
(infection control for waste disposal and decontamination measures).
Goals of
Smallpox Isolation
The primary
goal of smallpox isolation is to protect others from becoming infected.
Groups such as healthcare personnel, response personnel, and other
patients require protection from a smallpox patient.
It is imperative
that the smallpox patient is isolated. Isolation includes preventing
the sharing of airspace (respiratory isolation), preventing direct
contact (by using protective clothing) and preventing contact with
infectious materials (decontamination).
Respiratory
Isolation
Respiratory
isolation can be accomplished by placing the patient in negative
pressure isolation rooms. Respirators are required for unvaccinated
care-providers. Proper respiratory isolation is such that there
are at least 6 to 12 air changes per hour, the air is vented to
the outside, and air is not re-circulated to other rooms or areas.
Respiratory
protection for patients with suspected or confirmed smallpox, both
Airborne and Contact Precautions should be used in addition to
Standard Precautions. Airborne Precautions apply for patients infected
with microorganisms potentially transmitted by airborne droplet
nuclei 5 microns or smaller. These evaporated droplets contain
bugs, that can remain suspended in air, and be widely dispersed
by air currents. The respirator should at least meet the NIOSH
standard for particulate respirators, type N95. This is the same
recommendation that has been made for protecting health care workers
against tuberculosis infection.
If the outbreak
produces large numbers of patients that can’t be accommodated
in existing negative pressure rooms, or if no such rooms exist,
the patients should be isolated in separate facilities, since there
have been documented cases of smallpox transmission in patients
housed two floors below. If groups of suspected patients are isolated
in a facility designated only for care of smallpox patients, the:
- Special isolation
rooms are not needed.
- Make sure
that ventilation system (including heating and air conditioning
systems) are not shared with any other facility.
- All persons
entering facility must have been successfully vaccinated recently
(including patients admitted to facility)
Personal
Protective Equipment
Personnel should
use disposable gloves, gown, and shoe covers for all contact with
patients. This precaution is to prevent inadvertent transmission
of variola virus form clothing or other contaminated items. Personnel
should remove and correctly dispose of all protective clothing
before contacting with other people.
Reusable bedding
and clothing can be autoclaved or laundered in hot water with bleach
to inactivate the virus. People who come into contact with materials
potentially contaminated with smallpox virus, such as laundry handlers,
housekeeping, and laboratory personnel should utilize appropriate
protective equipment. If a case of smallpox is confirmed, these
personnel should be vaccinated before handling contaminated materials.
Isolation
Strategies
In a smallpox
outbreak, there are 3 groups to consider when formulating isolation
strategies. The first group is confirmed or suspected cases that
would be considered immediately infectious to others. The second
group is vaccinated contacts to smallpox cases that become febrile
and may be developing smallpox or may be febrile from the vaccination
or some other reason (potentially infectious). The final group
is vaccinated contacts to smallpox case that don’t have any
symptoms but who are still in the surveillance period for the development
of smallpox (not currently infectious but could still develop smallpox)
Febrile vaccinated
contacts must be isolated to assure that they are not experiencing
a fever because they have contracted smallpox. This precaution
is needed because the first stages of smallpox rash (the time when
the patient become contagious) may be quite subtle.
Recently vaccinated
contacts to smallpox cases that do not have any symptoms (FEVER) are not infectious so don’t require facilities with any special
ventilation. They can be monitored in their home for development
of a fever (check at least twice a day). Individuals in this group
can be asked to stay at home during surveillance period for symptoms
or may be allowed to travel outside of home if distance is restricted
such that a quick return to home is possible if develops fever.
All others staying in home must be vaccinated in case the contact
develops smallpox. Other household members with vaccination contraindications
that can’t be vaccinated to protect themselves if the contact
does develop smallpox while at home under surveillance should stay
elsewhere until the contact is no longer at risk of developing
the disease.
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