FluWatch report: August 30 to September 12, 2015 (Week 35-36)

Laboratory Confirmed Influenza Detections

Influenza detections remain at inter-seasonal levels in week 36, with 1.2% of tests positive for influenza (Figure 2).

Most jurisdictions have reported only sporadic numbers of influenza detections in recent weeks. Influenza detections have picked up in the west, with BC and AB accounting for 82% of influenza detections in Canada in week 36. The majority of detections in Canada have been influenza A (88%) and 100% of those subtyped have been A(H3N2).

Among cases with reported age, the largest proportion was in those ≥65 years of age (45%) (Table 1).

For additional data on other respiratory virus detections see the Respiratory Virus Detections in Canada Report on the Public Health Agency of Canada website.

Influenza-like Illness Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 15.8 consultations per 1,000 patient visits in week 35 to 8.4 per 1,000 visits in week 36. In week 36, the highest ILI consultation rate was found in the 20-64 age group and the lowest was found in the 0-4 age group (Figure 4).

Influenza Outbreak Surveillance

In weeks 35 and 36, no new outbreaks of influenza were reported.

Sentinel Pediatric Hospital Influenza Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

No laboratory-confirmed influenza-associated paediactric (≤16 years of age) hospitalizations have been reported by the Immnuzation Monitoring Program ACTive (IMPACT) network for the 2015-16 season.

Provincial/Territorial Influenza Hospitalizations and Deaths

See additional data on Reported Influenza Hospitalizations and Deaths in Canada: 2009-10 to 2014-15 on the Public Health Agency of Canada website.

Influenza Strain Characterizations

The National Microbiology Laboratory (NML) has not yet reported any influenza strain characterizations for the 2015-16 season (Figure 9).

Antiviral Resistance

The NML has not yet reported antivirual resistance results for influenza viruses collected during the 2015-16 season (Table 2).

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

FluWatch definitions for the 2015-2016 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

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.