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Small Pox        

New York City Department of Health
Bureau of Communicable Disease

Medical Treatment and Response
to Suspected Smallpox:
Information for Health Care Providers
During Biologic Emergencies

July 2000 Draft


  1. Key Summary Points
  2. Introduction/Epidemiology
  3. Significance as a Potential Bioterrorist Agent
  4. Clinical Manifestations
  5. Laboratory Diagnosis
  6. Handling Laboratory Specimens
  7. Treatment
  8. Isolation of Patients
  9. Disposal of Infectious Waste
  10. Autopsy and Handling of Corpses
  11. Management of Exposed Persons
  12. Reporting
  13. References




ALL SUSPECT CASES OF SMALLPOX MUST BE REPORTED IMMEDIATELY TO
THE BUREAU OF COMMUNICABLE DISEASE:
During Business Hours: 212-788-9830
After Hours (Nights, Weekends and Holidays): 212-POISONS


  1. KEY SUMMARY POINTS

    Epidemiology:

    Clinical:

    Diagnosis:

    Treatment:

    Prophylaxis:

    Patient Isolation:




    ALL SUSPECT CASES OF SMALLPOX MUST BE REPORTED IMMEDIATELY TO
    THE BUREAU OF COMMUNICABLE DISEASE:
    During Business Hours: 212-788-9830
    After Hours (Nights, Weekends and Holidays): 212-POISONS


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  2. Introduction/Epidemiology

    Smallpox is caused by an Orthopoxvirus, variola, a large enveloped DNA virus. The last occurrence of endemic smallpox was in Somalia in 1977 and the last human cases were laboratory-acquired infections in 1978. Smallpox was declared eradicated in 1980 by the World Health Organization.

    Variola is infectious only for humans; there is no animal reservoir. Other key epidemiologic points include:

    During the past century, the prototypical disease, variola major, caused mortality of 3% and 30% in the vaccinated and unvaccinated, respectively. The key to control and eventual eradication of endemic smallpox was vigorous case identification, followed by quarantine and immunization of contacts. Routine smallpox vaccination was discontinued in the United States in 1972. Immunity from prior smallpox vaccination wanes with time and at this point, the entire United States' civilian population is likely susceptible. However, persons who have been vaccinated in the past may experience less severe disease.

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  3. Significance as a Potential Bioterrorist Agent

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  4. Clinical Manifestations

    During an act of bioterrorism, release of an aerosol will be the most likely route of transmission.

    A. Variola major
    Incubation period - typically 12-14 days, can be 7-17 days

    Symptoms: Prodrome: Acute onset of malaise, fever, rigors, vomiting, headache and backache. 15% develop delirium. 10% of light skinned patients have an erythematous rash.

    Exanthem: Appears as soon as 2-3 days after prodrome, just as fever peaks.
    Discrete maculopapular rash on face, hands, forearms, and mucous membranes of mouth and pharynx. Involvement of palms and soles is common.
    Rash spreads to legs and then centrally to trunk during Week 2.
    Lesions quickly progress from macules to papules to vesicles to pustular vesicles (umbilicated) to crusty scabs.
    Scabs form 8-14 days after onset, leaving depressions and depigmented scars primarily on the face which has more sebaceous glands.

    CLINICAL CLUES TO DISTINGUISH SMALLPOX FROM CHICKENPOX:

    B. Variations in Variola Major

    Flat-type/"malignant" smallpox: Occurs in 2-5% of smallpox cases due to lack of adequate cell-mediate immune response. Notable for severe systemic toxicity and slow evolution of flat, soft, focal skin lesions. These papules coalesce and never become pustular. Skin develops a fine-grained reddish color, resembling crepe rubber. The mortality among unvaccinated persons is 95%.

    Hemorrhagic-type smallpox: Occurs in < 3% of smallpox cases. Notable for extensive petechia, mucosal hemorrhage and intense toxemia (high fevers, headache, backache and abdominal pain). Seen more commonly in pregnant women. Patients usually die before development of typical pox lesions. Differential diagnosis includes: meningococcemia and acute leukemia.

    C. Variola minor (alastrim)

    Incubation period - 7-17 days

    Symptoms - Clinically resembles variola major but with milder systemic toxicity and sometimes more diminutive pox lesions. Lesions on the face are typically more sparse and evolve more rapidly than those on the arms and legs. Mortality in the unvaccinated is usually less than 1%.

    D. Clinical Complications of Smallpox
    Arthritis and osteomyelitis: Frequency is 1-2%. Occurs late in course; usually affects children; bilateral elbow joint involvement most common.
    Cough and bronchitis: Occasionally a prominent symptom. Pneumonia was unusual.
    Pulmonary edema: Common in hemorrhagic and flat-type smallpox.
    Orchitis: Noted in 0.1% of patients.
    Encephalitis: Developed in 1 in 500 patients with variola major.
    Keratitis/corneal ulcers: Progresses to blindness in about 1% of cases.
    Disease during pregnancy: Precipitated high perinatal mortality.

    E. Monkeypox

    A naturally-occurring relative of variola, monkeypox virus, is a rare zoonosis that occurs in the rain forest areas of Africa and is felt to be rodent borne. The disease it causes, monkeypox, is clinically indistinguishable from smallpox, except for notable swelling of cervical and inguinal lymph nodes.

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  5. Laboratory Diagnosis




    If smallpox is suspected, please call the New York City Bureau of Communicable Disease at 212-788-9830 to arrange for submission of specimens to CDC for testing. After hours, please call the Poison Control Center at 212-POISONS (212-764-7667).


    The diagnosis of smallpox requires astute clinical evaluation. The clinical diagnosis may be confused with chickenpox, erythema multiforme with bullae or allergic contact dermatitis.

    The diagnosis of smallpox is an international emergency and confirmation of the diagnosis by laboratory techniques requires coordination between the medical and laboratory community and local, state, federal and international agencies. If you clinically suspect a case of smallpox, notify the New York City Department of Health IMMEDIATELY at 212-788-9830 (AFTER HOURS CALL 212-POISONS).

    In the event of a bioterrorist release of smallpox, confirmation by a reference laboratory will be necessary for the earliest (index) cases. After a smallpox outbreak is confirmed, diagnosis of subsequent cases will need to be based on a compatible clinical presentation.

    Vesicular fluid should be obtained by opening the lesions with the blunt edge of a sterile scalpel and harvesting the fluid as a droplet on a clean microscopic slide and allowing the sample to air dry in a safe location. Scabs can be removed with forceps. Specimens from different patients should not be mixed together. All specimens should be safely secured for shipping; at least three separate slides or a sterile tube with 3-4 scabs are preferred by the CDC laboratory for each patient tested. Specimens will be tested at the CDC's Biosafety Level 4 reference laboratory using the following tests:

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  6. Handling Laboratory Specimens

    All other laboratory tests should be performed in Biological Safety Level 2 cabinets and blood cultures should be maintained in a closed system. Laboratory staff handling specimens from persons who might have smallpox must wear surgical gloves, protective gowns and shoe covers. Every effort should be made to avoid splashing or creating an aerosol, and protective eye wear and masks should be worn if work cannot be done in a Biological Safety Level 2 cabinet. A full-face mask respirator with a HEPA (high efficiency particulate air) filter is an acceptable, but cumbersome, alternative to masks and protective eye wear. Laboratories working with a large amount of viral organisms should use Biological Safety Level 3 cabinets.

    Accidental spills of potentially contaminated material should be decontaminated immediately by covering liberally with a disinfectant solution (1% sodium hypochlorite or sodium hydroxide (0.1N)). All biohazardous waste should be decontaminated by autoclaving. Contaminated equipment or instruments may be decontaminated with a hypochlorite solution, 1% peracetic acid, formaldehyde, ethylene oxide, copper irradiation, or other O.S.H.A. approved solutions, or by autoclaving or boiling for 10 minutes.

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  7. Treatment

    Supportive care is the mainstay of therapy.

    Currently, there are no anti-viral drugs of proven efficacy. Although, adefovir, dipivoxil, cidofovir and ribavirin have significant in vitro antiviral activity against poxviruses, their efficacy as therapeutic agents for smallpox is currently uncertain. Cidofovir is FDA-licensed and shows the most promise in animal models.

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  8. Isolation of Patients

    Smallpox is transmissible from person-to-person by exposure to respiratory secretions (particularly from coughing patients), contact with pox lesions and by fomites (although not efficiently). All staff should observe both Airborne and Contact Precautions, in addition to Standard Precautions, when caring for patients with suspected or confirmed smallpox.

    Patients should be placed in a closed-door, negative pressure room with 6 to 12 air exchanges per hour and HEPA filtration of exhausted air. Patients with smallpox should be placed on strict isolation from the onset of eruptive exanthem until all pox scabs have separated (generally 14-28 days). Healthcare workers and others entering the room should wear appropriate respiratory protection; respiratory masks should meet the minimal NIOSH standard for particulate respirators (N95). Healthcare provides should wear clean gloves and gowns for all patient contact.

    In the event of a large-scale smallpox outbreak due to a bioterrorist attack, there may be massive numbers of victims. In this case, there may be a need to cohort patients due to limited availability of respiratory isolation rooms. If this is done, then all patients should receive smallpox vaccine or vaccine immune globulin within 3 days of exposure, if available, in the event that some of these patients are misdiagnosed with smallpox.

    All healthcare workers providing direct patient care to persons with smallpox should be vaccinated. If vaccine is unavailable, then only staff who previously received smallpox vaccine (e.g., persons born before 1972 or persons who were in the military before 1989) should be caring for patients with smallpox.

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  9. Disposal of Infectious Waste

    Use of tracking forms, containment, storage, packaging, treatment and disposal methods should be based upon the same rules as all other regulated medical wastes.

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  10. Autopsy and Handling of Corpses

    All postmortem procedures are to be performed using Universal Precautions. In addition, due to concerns about aerosolization of the virus, personnel should use particulate respirators as recommended under Strict Isolation precautions.

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  11. Management of Exposed Persons

    An exposed person is defined as a person who has been in close personal contact with a patient with suspect or confirmed smallpox. Close personal contact includes persons residing in the same household with the case-patient or persons with face-to-face contact with the case AFTER the case developed febrile illness. (During outbreaks in Europe in the 1960's, up to 10-20 secondary cases occurred after exposure to a single case-patient, if vaccination efforts were delayed.)

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  12. Reporting to the Health Department

    Smallpox is an international emergency and even an isolated suspect case must be reported immediately to the New York City Department of Health.

    All suspect cases should be immediately reported by telephone to:

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  13. References

    Breman JG, Henderson DA. Poxvirus dilemmas -- monkeypox, smallpox and biological terrorism. New Engl J Med 1998;339:556-559.

    Esposito JJ, Massung RF. Poxvirus infections in humans. In: Murray PR, Tenover F, Baron EJ, eds. Clinical Microbiology. Washington: American Society for Microbiology, 1995:1131-1138.

    Goldstein VA, Neff JM, Lande JM, Koplan JP. Smallpox vaccination reactions, prophylaxis and therapy of complications. Pediatrics 1975;55:342-347.

    Henderson DA, Inglesby TV, Bartlett JG, et al. Smallpox: Civilian medical and public health management following use of a biological weapon. Consensus statement of the Working Group on Civilian Biodefense. JAMA 1999: (Submitted for publication).

    Lane JM, Ruben FL, Neff JM, Millar JD. Complications of smallpox vaccination, 1968: National surveillance in the United States. New Engl J Med 1969;281:1201-1208.

    Mack TM. Smallpox in Europe, 1950-1971. JID 972;125:161-169.

    US Army Medical Research Institute of Infectious Diseases. Medical Management of Biological Casualties. 3rd Edition. Fort Detrick, MD. 1998.

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    July 2000


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