Smallpox

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Nationally notifiable since 2000

1.0 National Notification

Confirmed, probable cases and suspect cases of disease should be notified.

Contact the Public Health Agency of Canada immediately using the 24-hour emergency line 1-800-545-7661 even in the event of a suspected case.

2.0 Type of Surveillance

Routine case-by-case notification to the federal level

3.0 Case Classification

3.1 Confirmed case

Laboratory confirmation of infection:

• isolation of variola virus from an appropriate clinical specimen
  OR
• detection of variola virus nucleic acid

3.2 Probable case

Clinical evidence of illness in a person who is epidemiologically linked to a laboratory-confirmed case or to a probable case

OR
Laboratory evidence of infection:

• negative stain electron microscopic identification of variola virus in an appropriate clinical specimen

3.3 Suspect case

Clinical evidence of illness in a person who is not epidemiologically linked to a laboratory-confirmed case or to a probable case of smallpox
OR
Atypical lesion known to be associated with the variola virus on a person who is epidemiologically linked to a laboratory-confirmed or probable case

4.0 Laboratory Comments

Any testing related to suspected smallpox should be carried out under level 4 containment facilities at NML.

Contact the Public Health Agency of Canada immediately using the 24-hour emergency line (1-800-545-7661), even in the event of a suspected case, in order to activate the ERAP program.

5.0 Clinical Evidence

Smallpox is characterized by a febrile prodrome consisting of fever > 38.3° C and systemic symptoms (prostration, headache, back pain, abdominal pain and/or vomiting), which generally lasts one to four days and is followed by the development of a characteristic rash. The rash consists of deep, fi rm, well-circumscribed pustules that are mostly all in the same stage of development. The lesions are characteristically umbilicated. The lesions initially appear as macules, evolving into papules, vesicles and then pustules in a matter of days. Finally, crusted scabs form; they then fall off several weeks after the initial appearance of the rash. Lesions initially appear in the oral mucosa/palate and then progress in a centrifugal pattern to involve the face, arms, legs, palms and soles. Atypical presentations include fl at velvety lesions that do not evolve into pustules and more severe forms with confl uent or hemorrhagic lesions.

6.0 ICD Code(s)

6.1 ICD-10 Code(s)

B03

6.2 ICD-9 Code(s)

050

7.0 Type of International Reporting

Mandatory reporting to WHO in accordance with the International Health Regulations (2005)

Elimination or eradication efforts should be reported.

8.0 Comments

It should be noted that the US Centers for Disease Control and Prevention (CDC), Emergency Preparedness and Response, provides slightly different case definitions. The CDC case definitions can be found at http://www.bt.cdc.gov/agent/smallpox/diagnosis/casedefinition.asp

9.0 References

Case definitions for diseases under national surveillance. CCDR 2000;26(S3). Retrieved May 2008, from http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/00vol26/26s3/index.html

Communicable Diseases Network Australia. Interim Surveillance Case Definitions for the Australian National Notifiable Diseases Surveillance System. Version 1.1. 2004:61. Retrieved May 29, 2007 from http://www.health.gov.au/internet/wcms/publishing.nsf/Content/cda_surveil-nndss-dislist.htm#casedefs

Damon I. Orthopoxviruses: vaccinia (smallpox vaccine), variola (smallpox), monkeypox and cowpox. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 6th ed. Vol 2. Philadelphia: Churchill Livingstone. Elsevier, 2006.

World Health Organization. Fifty-eighth World Health Assembly. Resolution WHA58.3: Revision of the International Health Regulations. 2005. Retrieved May 8, 2007 from www.who.int/gb/ebwha/pdf_files/WHA58/WHA58_3-en.pdf

Date of Last Revision/Review:

May 2008