Laboratory confirmation of infection:
- isolation of variola virus from an appropriate clinical specimen (tier 3 laboratory only);
OR - detection of variola virus nucleic acid.
- Clinical evidence of illness in a person who is epidemiologically linked to a laboratory-confirmed case or to a probable case;
OR - Laboratory confirmation of infection: negative stain electron microscopy identification of variola virus in an appropriate clinical specimen.
- Clinical 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.
Notes:
- Clinical illness is characterized by acute onset of fever of > 38.3 °C and systemic symptoms (prostration, headache, back pain, abdominal pain, and/or vomiting) which generally lasts 1-4 days and is followed by the development of a characteristic rash. This rash consists of deep, firm, 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; then they 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 of smallpox include flat velvety lesions that do not evolve into pustules and more severe forms with confluent or hemorrhagic lesions.
- 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.
