National case definition: Diphtheria
Date of last revision/review: May 2008
Only confirmed cases of disease should be notified.
Type of surveillance
Routine case-by-case notification to the federal level
Clinical illness (see Clinical Evidence section) or systemic manifestations compatible with diphtheria in a person with an upper respiratory tract infection or infection at another site (e.g. wound, cutaneous) plus at least one of the following:
- Laboratory confirmation of infection:
- isolation of Corynebacterium diphtheriae with confirmation of toxin from an appropriate clinical specimen, including the exudative membrane
- isolation of other toxigenic Corynebacterium species (C. ulcerans or C. pseudotuberculosis) from an appropriate clinical specimen, including the exudative membrane
- histopathologic diagnosis of diphtheria
- Epidemiologic link (contact within two weeks prior to onset of symptoms) to a laboratory-confirmed case
Clinical illness in the absence of laboratory confirmation or epidemiologic link to a laboratory-confirmed case
Upper respiratory tract infection (nasopharyngitis, laryngitis or tonsillitis) with or without a nasal, tonsillar, pharyngeal and/or laryngeal membrane
Isolation of Corynebacterium species capable of producing diphtheria toxin (C. diphtheriae, C. ulcerans or C. pseudotuberculosis) should be tested using the modified ELEK assay OR assay for the presence of the diphtheria tox gene, which, if detected, should be tested for expression of diphtheria toxin using the modified ELEK assay
Clinical illness is characterized as an upper respiratory tract infection (nasopharyngitis, laryngitis or tonsillitis) with or without an adherent nasal, tonsillar, pharyngeal and/or laryngeal membrane, plus at least one of the following:
- gradually increasing stridor
- cardiac (myocarditis) and/or neurologic involvement (motor and/or sensory palsies) one to six weeks after onset
- death, with no known cause
Suspect and probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes.
Although rare, other toxigenic Corynebacterium species (C. ulcerans or C. pseudotuberculosis) may cause clinical diphtheria. Cases with clinically compatible illness and isolation of other toxigenic Corynebacterium species are nationally notifiable.
Significant, systemic disease is occasionally caused by non-toxigenic strains of these species in specific patient populations.
Laboratory Centre for Disease Control. Guidelines for the control of diphtheria in Canada. CCDR 1998;24(S3).
De Winter LM, Bernard KA, Romney MG. Human clinical isolates of Corynebacterium diphtheriae and Corynebacterium ulcerans which do not meet the criteria for notifiable diphtheria in Canada 1999-2003. J Clin Microbiol 2005;43:3447-9.
Romney MG, Roscoe DL, Bernard K, Lai S, Efstratiou A, Clarke AM. Emergence of an invasive clone of non-toxigenic Corynebacterium diphtheriae in Vancouver's urban poor. J Clin Microbiol 2006;44:1625-9.
Previous case definitions
Canadian Communicable Disease Surveillance System: disease-specific case definitions and surveillance methods. Can Dis Wkly Rep 1991;17(S3).
Case definitions for diseases under national surveillance. CCDR 2000;26(S3)
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