FluWatch report: October 30 to November 5, 2016 (week 44)

Overall Summary

• Influenza activity is at interseasonal levels with the majority regions in Canada reporting low activity.
• A total of 147 positive influenza detections were reported in week 44. Influenza A(H3N2) continues to be the most common subtype detected.
• In week 44, 1.4% of visits to sentinel healthcare professionals were due to influenza-like symptoms, a slight increase from week 43.
• Nine laboratory-confirmed influenza outbreaks were reported in week 44.
• Ten hospitalizations were reported in week 44; all due to influenza A(H3N2). The first influenza-associated deaths of the season were reported in week 44, but cumulative counts remain low (less than five deaths).
• For more information on the flu, see our Flu(influenza) web page.

On this page

• Influenza/Influenza-like Illness (ILI) Activity (geographic spread)
• Laboratory Confirmed Influenza Detections
• Syndromic/Influenza-like Illness Surveillance
• Influenza Outbreak Surveillance
• Provincial/Territorial Influenza Hospitalizations and Deaths
• Sentinel Hospital Influenza Surveillance
• Influenza Strain Characterizations
• Antiviral Resistance
• Provincial and International Influenza Reports
• FluWatch definitions for the 2016-2017 season

Influenza/Influenza-like Illness (ILI) Activity (geographic spread)

In week 44, a total of 19 regions reported no influenza activity. Sporadic influenza activity was reported in 16 regions across eight provinces (BC, AB, SK, ON, QC, NS, NF and YK). Localized activity was reported in six regions across three provinces (AB, ON and QC). For more details on a specific region, click on the map.

Laboratory Confirmed Influenza Detections

The percentage of tests positive for influenza increased in week 44 but remained at interseasonal levels, with 3.9% of tests positive for influenza. 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 week 44, there were 147 positive influenza tests. Influenza A(H3N2) was the most common subtype detected. BC and AB accounted for the majority (65%) of influenza detections in week 44. To date, influenza A(H3N2) is the most common subtype detected, representing 73% of laboratory-confirmed detections. 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 over 536 laboratory confirmed influenza cases. Adults aged 65+ accounted 46% of reported influenza cases. Among cases of influenza A(H3N2), adults aged 65+ accounted for 48% of cases.

Syndromic/Influenza-like Illness Surveillance

Healthcare Professionals Sentinel Syndromic Surveillance

In week 44, 1.4% of visits to healthcare professionals were due to ILI. The proportion of ILI visits increased slightly from the previous week.

Influenza Outbreak Surveillance

In week 44, nine laboratory confirmed influenza outbreaks were reported: five in long-term care (LTC) facilities, two in hospitals and two in institutions or community settings. Of the outbreaks with known strains or subtypes, one outbreak was due to influenza A(H3N2) (in a LTC facility) and one outbreak was due to influenza A (unsubtyped) (in a LTC facility). To date this season, 29 outbreaks have been reported and the majority (66%) have occurred in LTC facilities.

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 49 influenza viruses [38 A(H3N2), 2 A(H1N1), 9 influenza B].

Antiviral Resistance

During the 2016-17 season, the National Microbiology Laboratory (NML) has tested 50 influenza viruses for resistance to oseltamivir and zanamivir and 30 influenza viruses for resistance to amantadine. All 50 viruses weres sensitive to oseltamivir and zanamivir. All 30 influenza A viruses were resistant to amantadine (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.