ARCHIVED - Guidelines for the Prevention and Control of Meningococcal Disease
6.0 Surveillance of Invasive Meningococcal Disease in Canada
IMD is reportable in all provinces and territories and is nationally notifiable. Each province or territory has procedures in place for the rapid notification of cases to medical officers of health and timely reporting to the appropriate provincial or territorial public health official.
Both confirmed and probable cases of IMD are notifiable at the national level. Provinces and territories report case-by-case data with basic core variables on a weekly basis to the Notifiable Diseases Reporting System. In addition, the Immunization and Respiratory Infections Division (IRID), Centre for Infectious Disease Prevention and Control, Public Health Agency of Canada, conducts enhanced surveillance for IMD. Provinces and territories report more detailed epidemiologic and laboratory data for each case to the IRID. Detailed surveillance reports are published periodically in the CCDR; the most recent report was published in February 2004(2).
Most jurisdictions rely on passive surveillance for identification of cases. When an increase in the incidence of IMD is suspected in a particular region, there should be heightened surveillance for cases and the collection of more detailed epidemiologic and microbiologic information.
The following steps should be taken:
- The provincial or territorial epidemiologist or medical health officer should be consulted immediately to decide whether the increased incidence constitutes an outbreak.
- Active surveillance should be initiated. Epidemiologic information should be obtained on each case, with the objective of identifying high-risk groups and determining associations that will permit targeted control interventions. The data collected should include age; sex; place of residence; vaccination status, including the type of meningococcal vaccine, the number of doses and age at vaccine administration; recent travel; attendance or employment at a day care centre or school; and participation in recent athletic or recreational events and gatherings. Other information relevant to the outbreak should also be collected (e.g. social or cultural setting).
- Basic epidemiologic analysis should include age-group-specific attack rates (calculated for 5-year age groups), serogroup-specific rates and case fatality ratios. Techniques such as historical modeling can be used to determine whether the current incidence is greater than in previous years; this is particularly important in light of the seasonality of the disease.
- The province or territory should notify the IRID of the increase in IMD incidence, and the IRID will relay the information to the other provinces and territories.
- When an outbreak is suspected, serogroup determination becomes critical for appropriate decisions regarding control measures. Provincial and territorial public health laboratories, in collaboration with the NML, may conduct typing, subtyping and other genotyping tests (e.g. PFGE) that have proven helpful in characterizing outbreaks and determining disease trends.
- During outbreaks or whenever there is failure to isolate or determine the serogroup of an organism, clinical specimens should immediately be forwarded by the provincial laboratory to the NML, Public Health Agency of Canada, for molecular diagnostic testing and further strain identification.
At this time conjunctivitis and pneumonia cases due to N. meningitidis are not nationally notifiable and reported to the Public Health Agency of Canada. However the following definitions and suggested treatments have been made. A conjunctivitis case requires isolation of N. meningitidis from the eye or the conjunctival sac in association with purulent conjunctivitis. A pneumonia case is one with a Gram strain (if done) showing Gram-negative diplococci and a polymorphonuclear cell response from sputum or respiratory aspirate, isolation with heavy growth of N. meningitidis and clinical or radiological evidence of pneumonia. Patients with N. meningitidis conjunctivitis or pneumonia should be treated with appropriate systemic antibiotics(28).
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