Questions and Answers About Infection Control and Isolation of Smallpox Patients

Once a smallpox patient has been identified, what is the response for the hospital or clinic? Do we quarantine?
Until a case is confirmed, our recommendation would be the same as for any rash illness, such as measles. Get the suspect patient into a negative air pressure room and gather the name and locating information for those exposed to the patient. If they don’t have a negative air pressure room, get them to a facility that does. State and local governments have primary responsibility for isolation and/or quarantine within their borders. The federal government may isolate and/or quarantine smallpox cases when there is the potential for interstate spread of disease or the importation of disease among passengers arriving from foreign countries. You should consult with your state or local attorney for advice on isolation and quarantine within your jurisdiction.

Why are we even bringing smallpox patients to the hospitals? Why not just keep them at home where they’ve already exposed everyone? 
With good infection control practices and rooms with the appropriate air handling features, we can treat patients in the hospital without risking transmission to other patients and staff. The appropriate care and management of smallpox patients will probably require hospitalization. 

Does a HEPA filter remove smallpox virus? Can a makeshift isolation room be created by bringing a portable HEPA filter into a regular private room?
Yes, HEPA filters do remove smallpox virus. HEPA filters are 99.97% efficient at removing particles that are greater than or equal to 0.3 microns in size, but their use will not create an airborne infection isolation room, (the precautions recommended for smallpox patients). The HEPA filter will not change the pressure relationship to the corridor unless the portable filter is set up as a negative pressure device. Self-closing doors will help to maintain the conditions and windows should be closed and sealed. If the HEPA filter is being used only to purify the room air, its effectiveness will vary depending on the size of the room and output of the device. A portable HEPA filter that produces 8 or more air changes per hour results in a 90% reduction of particles in 17 minutes in a room with the doors and windows closed. However, to be consistent with current guidelines for airborne infection isolation rooms, the goal should be 12 or more air changes per hour which would produce a 90% reduction in particles in 11 minutes.

What kind of personal protective equipment (PPE, especially respiratory) would be necessary for dealing with a smallpox patient?
Anyone caring for a smallpox patient should wear an N95 mask. Airborne and contact isolation precautions should be followed. Please see “Guideline for Isolation Precautions in Hospitals” for further information.

If a health care provider has a contraindication or is at a high risk for infection, should they care for patients infected with smallpox?
Ideally, these providers should not be in the vicinity of the patient or performing any patient care.

Is there documentation of the time/temperature necessary for sterilizing potentially smallpox-infected material using autoclave/steam sterilization?
The standard time and temperature requirements for steam/autoclave sterilization are adequate to kill the smallpox virus. Items contaminated with the smallpox virus should be sterilized using the same sterilization parameters recommended by the manufacturers’ of the instrument, the sterilizer and the container or wrap.

Are there alternative methods of sterilizing hospital laundry contaminated with smallpox virus other than autoclaving or ethylene oxide decontamination?
There is no need to autoclave or apply other decontamination procedures prior to laundering. Only vaccinated personnel should handle laundry contaminated with the smallpox virus. Protective attire should be worn, including gown, gloves, and N-95 respirator. Standard practices to safely contain contaminated laundry to prevent direct contact and generation of aerosols should be followed. Bagged laundry should be placed directly into the washer without prior sorting. Current recommendations for commercial laundering with hot water should be followed.

When morticians are handling bodies infected with smallpox after death, what is the risk for infection?
Morticians/mortuary workers are in the recommended occupational categories for smallpox vaccination in the current program because of their possible involvement in a first response to a smallpox outbreak resulting in death. Only vaccinated personnel should perform or participate in autopsies or burial preparation of suspected smallpox cases.

Extreme precautions are necessary to prevent dissemination of smallpox virus during an autopsy or burial preparation. Standard precautions should be observed for all contact with the body. To transport the body to the preparation location, the body should be wrapped in a large, impervious plastic bag, or a disaster pouch, that is sealed airtight with tape. The body should be sealed in a second large, impervious plastic bag prior to transportation to the preparation suite. Ideally, the preparation would be performed in a room with negative air pressure with respect to the surrounding facilities. All doors and windows of the autopsy rooms should be closed during the preparation, and the air exhausted must not be recirculated. Only necessary personnel with up-to-date vaccination (within 3 years) should participate in the preparation. Vaccinated personnel should wear disposable clothing, gowns, gloves, caps, booties, and masks and face shields or protective eyewear to prevent splashing of the mucus membranes. No personal clothing should be worn. All clothing articles from the preparation room should be placed in biohazard bags and autoclaved or incinerated. Surfaces that may be contaminated with smallpox virus can be decontaminated with disinfectants that are used for standard infection control, such as hypochlorite and quaternary ammonia. After preparation, the body should be double-bagged as described above, in another set of large, impervious plastic bags. Patients who die secondary to smallpox should be cremated whenever possible.

If vaccination prior to participation in the burial preparation is not possible, unvaccinated personnel should perform the preparation wearing, in addition to the protective garments above, respiratory protection (e.g., HEPA-filtered breathing apparatus or a self-contained breathing apparatus).

Contact CDC (NCID Division of Healthcare Quality Control at 404-639-6413 or Pathology Activity 404-639-3133) prior to an autopsy/burial preparation, in order to review the containment features of individual autopsy/burial preparation suites, procedures for autopsy,/preparation and disinfection after an autopsy/burial preparation.

What made the 1970 German hospital smallpox case airborne versus other cases? How big or small do dust particles have to be to make variola airborne from droplet nuclei?
No one is sure why there appears to have been exceptional, apparent aerosol spread of virus in Meschede, Germany, in 1970. One must assume the index case must have been coughing out incredible amounts of virus. The observation that aerosol transmission probably occurred, was based on epidemiologic investigations that occurred after the outbreak; to be most correct, infectious aerosols were never actually experimentally demonstrated (which would have been quite difficult/impossible at the time). An important feature of this tragic event also involves the observation that despite post-exposure vaccination, a substantial number of apparently aerosol-contact patients still died. It may be noteworthy that, unlike currently accepted protocols, the potential contacts in the Meschede outbreak were first vaccinated with a non-WHO-approved local vaccine and then secondarily with WHO-approved vaccine. It is possible that this atypical, two-phased, post-exposure treatment regimen, may have contributed in some way to the poor success of post-exposure vaccination observed in this one example. The mortality from the outbreak clearly has helped to focus attention on the outbreak in general.

Page last reviewed: March 13, 2009