FluWatch report: September 11 to September 24, 2016 (weeks 37-38)

In week 38, a total of forty of regions in Canada reported no influenza activity. Sporadic influenza activity was reported in nine regions. For the first time this season, localized activity was reported. A total of three regions across Ontario, Alberta and British Columbia reported localized activity in week 38.  For more details on a specific region, click on the map.

Laboratory Confirmed Influenza Detections

The percentage of tests positive for influenza remained at interseasonal levels, ranging from 1.2% in week 37 to 1.9% in week 38. For data on other respiratory virus detections, see the Respiratory Virus Detections in Canada Report on the Public Health Agency of Canada (PHAC) website.

Nationally in weeks 37-38, there were 73 positive influenza tests reported. Influenza A(H3N2) was the most common subtype detected in weeks 37 and 38. Many regions across Canada continue to report no influenza detections (SK, MB, NB, NS, PE, NT, NU). For more detailed weekly and cumulative influenza data, see the text descriptions for figures 2 and 3 or the Respiratory Virus Detections in Canada Report.

To date this season, detailed information on age and type/subtype has been received for 81 cases. Adults aged 65+ accounted for the greatest proportion of influenza cases (Table 1).

Syndromic/Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In week 38, 1% of visits to healthcare professionals were due to ILI. The ILI rate has remained constant since week 35.

Influenza Outbreak Surveillance

In weeks 37-38, four laboratory confirmed influenza outbreaks were reported. The first outbreak this season was reported in a long term care facility (LTCF) in week 37. Of the three outbreaks with known types or subtypes, one outbreak was due to influenza A (H3N2) and two were due to influenza A (unsubtyped).

Provincial/Territorial Influenza Hospitalizations and Deaths

Sentinel Hospital Influenza Surveillance

Pediatric Influenza Hospitalizations and Deaths

To date this season, less than five laboratory-confirmed influenza-associated pediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network.

Influenza Strain Characterizations

During the 2016-17 influenza season, the National Microbiology Laboratory (NML) has characterized two influenza viruses, both influenza B.

Antiviral Resistance

During the 2016-17 season, the National Microbiology Laboratory (NML) has tested two influenza viruses for resistance to oseltamivir and zanamivir. Both viruses were sensitive to oseltamivir and zanamivir (Table 4).

Provincial and International Influenza Reports

• World Health Organization influenza update
• World Health Organization FluNet
• WHO Influenza at the human-animal interface
• Centers for Disease Control and Prevention seasonal influenza report
• European Centre for Disease Prevention and Control - epidemiological data
• South Africa Influenza surveillance report
• New Zealand Public Health Surveillance
• Australia Influenza Report
• Pan-American Health Organization Influenza Situation Report

• Alberta Health - Influenza Surveillance Report
• BC - Centre for Disease Control (BCCDC) - Influenza Surveillance
• New Brunswick - Influenza Surveillance Reports
• Newfoundland and Labrador - Surveillance and Disease Reports
• Nova Scotia - Flu Information
• Public Health Ontario - Ontario Respiratory Pathogen Bulletin
• Quebec - Système de surveillance de la grippe
• Manitoba - Epidemiology and Surveillance - Influenza Reports
• Saskatchewan - influenza Reports
• PEI - Influenza Summary

FluWatch definitions for the 2016-2017 season

Abbreviations: Newfoundland/Labrador (NL), Prince Edward Island (PE), New Brunswick (NB), Nova Scotia (NS), Quebec (QC), Ontario (ON), Manitoba (MB), Saskatchewan (SK), Alberta (AB), British Columbia (BC), Yukon (YT), Northwest Territories (NT), Nunavut (NU).

Influenza-like-illness (ILI): Acute onset of respiratory illness with fever and cough and with one or more of the following - sore throat, arthralgia, myalgia, or prostration which is likely due to influenza. In children under 5, gastrointestinal symptoms may also be present. In patients under 5 or 65 and older, fever may not be prominent.

ILI/Influenza outbreaks

Schools:

Greater than 10% absenteeism (or absenteeism that is higher (e.g. >5-10%) than expected level as determined by school or public health authority) which is likely due to ILI.
Note: it is recommended that ILI school outbreaks be laboratory confirmed at the beginning of influenza season as it may be the first indication of community transmission in an area.

Hospitals and residential institutions:

two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case. Institutional outbreaks should be reported within 24 hours of identification. Residential institutions include but not limited to long-term care facilities (LTCF) and prisons.

Workplace:

Greater than 10% absenteeism on any day which is most likely due to ILI.

Other settings:

two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case; i.e. closed communities.

Note that reporting of outbreaks of influenza/ILI from different types of facilities differs between jurisdictions.

Influenza/ILI activity level

1 = No activity: no laboratory-confirmed influenza detections in the reporting week, however, sporadically occurring ILI may be reported

2 = Sporadic: sporadically occurring ILI and lab confirmed influenza detection(s) with no outbreaks detected within the influenza surveillance region ^{Footnote †}

3 = Localized:

1. evidence of increased ILI^{Footnote *} and
2. lab confirmed influenza detection(s) together with
3. outbreaks in schools, hospitals, residential institutions and/or other types of facilities occurring in less than 50% of the influenza surveillance region^{Footnote †}

4 = Widespread:

1. evidence of increased ILI^{Footnote *} and
2. lab confirmed influenza detection(s) together with
3. outbreaks in schools, hospitals, residential institutions and/or other types of facilities occurring in greater than or equal to 50% of the influenza surveillance region^{Footnote †}

Note: ILI data may be reported through sentinel physicians, emergency room visits or health line telephone calls.