Smallpox

Isolation and Decontamination

Patients should be considered infectious from onset of rash until all scabs separate and should be isolated using droplet and airborne precautions during this period. In the civilian setting, strict quarantine of asymptomatic contacts for 17 days after exposure may prove to be impractical and impossible to enforce. A reasonable alternative would be to require contacts to check their temperatures daily. Any fever above 38°C (101°F) during the 17 days after exposure to a confirmed case would suggest the development of smallpox. The contact should then be isolated immediately, preferably at home, until smallpox is either confirmed or ruled out and remain in isolation until all scabs separate.

Hospital Infection Control (Including Autopsies and Burial)

Isolation Precautions

Airborne and Contact Precautions in addition to Standard Precautions should be implemented for patients with suspected smallpox.

Airborne Precautions:

  • Place the patient in a private room with negative air-pressure ventilation (minimum 6 air exchanges/hr).
  • Use external air exhaust or high-efficiency particulate air (HEPA) filters if the air is recirculated.
  • Keep the door to the room closed.

Contact Precautions:

  • Place the patient in a private room if available.
  • If a private room is not available, place the patient in a room with a patient who has active infection with the same organism (ie, cohort patients with smallpox).
  • Wear gloves when entering the room, change gloves after having contact with infectious material, remove gloves before leaving the room, and immediately wash hands using an antimicrobial agent.
  • Wear a gown when entering the room if clothing will have significant patient contact; remove the gown before leaving the room.
  • Move and transport the patient for essential purposes only. If transport is necessary, a mask should be placed on the patient.
  • When possible, dedicate the use of noncritical patient-care equipment.

Vaccination of Healthcare Workers

All healthcare workers caring for patients with suspected smallpox should be vaccinated immediately.

Cleaning and Disinfection of Environmental Surfaces

No disinfectant products are registered by the US Environmental Protection Agency (EPA) specifically for variola virus inactivation; however, according to CDC, products that inactivate similar lipid or medium-sized viruses (such as vaccinia virus) are adequate for disinfection of variola virus (see References: CDC: Smallpox response plan and guidelines, Guide F). These products include chemicals used on environmental surfaces for low- or intermediate-level disinfection and are outlined in the table below. High-level disinfectants or liquid chemical sterilants are not indicated for cleaning large environmental surfaces (eg, floors, walls, tabletops).

Chemicals Used on Environmental Surfaces for Low- or Intermediate-Level Disinfection

Disinfectant

Minimum Concentration to Achieve Inactivation

Ethyl alcohol

40%

Isopropyl alcohol

40%

Benzalkonium chloride

100 ppm

Sodium hypochlorite

200 ppm

Ortho-phenylphenol

40%

Iodophor

75 ppm

Abbreviation: ppm, parts per million.

 

Disinfection/Sterilization of Reusable Medical Equipment

Standard disinfection/sterilization methods approved by the FDA for medical instruments and devices are considered adequate for medical equipment used on smallpox patients, according to Guide F of the CDC Smallpox Response Plan (CDC 2002: Smallpox response plan and guidelines, Rutala 1996).

Laundry and Waste

Guide F of the CDC Smallpox Response Plan also outlines the following recommendations for management of textiles and fabrics:

  • Items should be handled with a minimum amount of agitation to avoid contamination of air, surfaces, and persons.
  • Textiles and fabrics (including clothing) should be bagged at the point of use in accordance with Occupational Safety and Health Administration (OSHA) regulations. Laundry should be labeled to indicate that laundry staff should wear appropriate personal protective equipment (as specified by OSHA rules on exposure to bloodborne pathogens).
  • Laundry can be washed using routine protocols for healthcare facilities (ie, hot water [71ºC or 160ºF] with detergent, bleach, and hot air drying)

The Working Group on Civilian Biodefense recommends that bedding and clothing of smallpox patients should be autoclaved or laundered in hot water to which bleach has been added (Henderson 1999: Smallpox as a biological weapon: medical and public health management).

Decontamination of Air Space

Laboratory dispersion studies involving vaccinia virus indicate that infectious virions are rapidly inactivated in the environment (CDC 2002: Smallpox response plan and guidelines). In one study, only 10% to 30% of viable variola viruses were recovered from controlled aerosols after 1 hour (Mayhew 1970). Therefore, there is no evidence to support air space decontamination of rooms, facilities, or vehicles (eg, fumigation). Standard terminal cleaning practices are considered adequate for rooms that have housed smallpox patients.

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