Influenza activity in Canada remained similar to previous weeks
During week 07, overall influenza activity in Canada remained fairly similar to previous weeks. Widespread influenza activity was reported by 4 regions (in BC & ON) and localized influenza activity by 10 regions (in BC, AB, SK, MB, ON, & QC). Eleven regions reported no activity and 30 reported sporadic activity (see map). Note: No data was received from a region in NB this week. In week 07, the percentage of specimens that tested positive for influenza was 13% (595/4,528) for Canada as a whole; and regionally ranging from 42% in BC to 4% in NL. The proportion of influenza B detections in Canada continued to increase over previous weeks, accounting for 34% of detections in week 07; however, the majority of influenza detections were still for influenza A viruses. Regionally, the majority of influenza B detections were reported from AB and BC (see table). This week, the ILI consultation rate was 19 ILI consultations per 1,000 patient visits (see ILI graph), which is below the expected range for this week. The sentinel response rate was 59%. Twenty one new outbreaks of influenza or ILI were reported this week as follows: 8 LTCFs, 12 schools, and 1 other.
*** On 20 February 2008, human metapneumovirus (hMPV) outbreaks were reported in ProMED in 2 facilities in the Cypress Health Region of SK. This is not unusual. HMPV is a relatively common respiratory virus. The Alberta Provincial Laboratory reported that roughly 12% of the respiratory outbreaks in LTCF and schools in the province were due to hMPV in the 2005-2006 influenza season and this is consistent with findings from the NML.

Antigenic Characterization:
The National Microbiology Laboratory (NML) has characterized 406 influenza viruses for the 2007-2008 influenza season: 247 (61%) A(H1N1), 38 (9%) A(H3N2) and 121 (30%) B viruses. All influenza A(H1N1) viruses were antigenically similar to A/Solomon Islands/3/2006. Of the 38 influenza A(H3N2) viruses characterized, 5 (13%) were antigenically similar to A/Wisconsin/67/2005 and 33 (87%) were antigenically similar to A/Brisbane/10/2007. One of the 5 A/Wisconsin-like viruses had reduced titer to A/Wisconsin/67/2005 reference antiserum. Of the 121 influenza B isolates characterized, 3 (2%) were antigenically similar to B/Malaysia/2506/2004 and 118 (98%) were antigenically similar to B/Florida/4/2006 (belonging to the B/Yamagata lineage) (see pie chart).

*** The WHO recommends that the vaccines to be used in the 2008-2009 season (northern hemisphere) contain the following: an A/Brisbane/59/2007 (H1N1)-like virus; an A/Brisbane/10/2007 (H3N2)-like virus; and a B/Florida/4/2006-like virus.

• WHO

Antiviral Resistance:
Since the start of the season, the NML has tested 330 influenza A isolates (262 H1N1 and 68 H3N2) for amantadine resistance and found that 66 (97.1%) of the 68 H3N2 isolates were resistant to amantadine and 4 (1.5%) of 262 H1N1 isolates were resistant (see recommendation from the 2006-2007 influenza season below).
The NML has also tested 351 influenza isolates (211 A/H1N1, 36 A/H3N2 & 104 B) for oseltamivir (Tamiflu) resistance and found that 20 (9.5%) of the 211 H1N1 isolates tested were resistant to oseltamivir. The resistant isolates were from NL (4), ON (13), MB (1) and BC (2). These oseltamivir resistant strains remain sensitive to the antiviral amantadine.

Influenza-associated Paediatric Hospitalizations:
No new laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network this week. To date, 21 hospitalizations have reported so far (all from Ontario) and all have been due to influenza A.

International:

WHO: During weeks 6–7, the level of overall influenza activity in the world remained the same with the majority of influenza activity observed and viruses detected were in most countries of Northern Europe and North America which is expected for this time of the year. Influenza A (H1N1) viruses predominated, however A(H3N2) and B viruses also circulated.

• WHO

CDC: During week 06, influenza activity continued to increase in the United States. The proportion of specimens that tested positive for influenza virus increased to 33% this week. Since September 30, 2007, CDC antigenically characterized 250 influenza viruses: 117 influenza A(H1) (107 A/Solomon Islands/3/2006-like and 10 showed somewhat reduced titers with antisera produced against A/Solomon Islands), 65 influenza A(H3) (9 A/Wisconsin/67/2005-like and 53 A/Brisbane/10/2007-like, and 3 showed somewhat reduced titers with antisera produced against A/Wisconsin and A/Brisbane), and 68 influenza B viruses (4 belonging to the B/Victoria and 64 B/Yamagata lineage). Small numbers of influenza viruses resistant to oseltamivir have been detected in the United States, representing 4.6% (16/350) of all influenza viruses tested (8.1% among H1N1 viruses tested).

• CDC

EISS: In week 07, influenza activity was changing or declining in most European countries. Compared to the detection of influenza A, the proportion of influenza B has increased from 14% in week 01 to 37% in week 07. A significant proportion (19.2%) of the A(H1N1) viruses circulating in Europe were resistant to oseltamivir with resistant viruses found in 15 European countries.

• EISS

Human Avian Influenza: Since 16 February 2008, the WHO reported 5 additional cases (all fatal) of H5N1 avian influenza infection: 2 from Indonesia, 2 from China and 1 from Viet Nam.

• WHO

Recommendation for the Use of Amantadine for Treatment and Prevention of Influenza
The Public Health Agency of Canada does not recommend the use of amantadine for treatment or prevention of influenza for the 2006-2007 season. This recommendation will be revisited if new information becomes available.

---

Total number of influenza tests performed and number of positive tests by province/territory of testing laboratory, Canada, 2007-2008

Province of reporting laboratories	Report Period: February 10 to February 16, 2008				Season to Date: August 26, 2007 to February 16, 2008
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	55	0	2	2	431	32	16	48
PE	4	0	1	1	48	0	3	3
NS	19	3	0	3	323	6	3	9
NB	39	6	3	9	390	10	13	23
QC	1338	178	20	198	12004	510	73	583
ON	1273	52	21	73	16394	829	79	908
MB	107	8	2	10	1728	21	8	29
SK	278	32	18	50	3141	127	68	195
AB	1234	70	103	173	17883	454	517	971
BC	181	42	34	76	1912	329	112	441
Canada	4528	391	204	595	54254	2318	892	3210

 

Specimens from NT, YT, and NU are sent to reference laboratories in other provinces.

Note: Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.

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)

Respiratory virus laboratory detections in Canada, by geographic regions, are available weekly on the following website:
<http://www.phac-aspc.gc.ca/bid-bmi/dsd-dsm/rvdi-divr/index-eng.php>

Number of influenza surveillance regions† reporting widespread or localized influenza activity, Canada, by report week, 2007-2008 (N=54)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.

Influenza Activity Level by Provincial and Territorial Influenza Surveillance Regions, Canada, 10 February to 16 February , 2008 (Week 7)
	No Data No Activity Sporadic Activity Localized Activity Widespread Activity

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and outbreaks. Please refer to detailed definitions. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website. Select single maps by report week to get this updated information.
<http://dsol-smed.phac-aspc.gc.ca/dsol-smed/fluwatch/fluwatch.phtml?lang=e>

Click on the map to view provinces/territories and maps for other weeks.

Influenza tests reported and percentage of tests positive, Canada, by report week, 2007-2008

Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2007-2008

Influenza strain characterization, Canada, cumulative, 2007-2008 influenza season by the Respiratory Viruses Section at the National Microbiology Laboratory
[N=406]

{Strain characterization, number identified, per cent of total number}

NACI recommends that the trivalent vaccine for the 2007-2008 season in Canada contain A/Solomon Islands/3/2006 (H1N1)-like virus; an A/Wisconsin/67/2005 (H3N2)-like virus; and a B/Malaysia/2506/2004-like virus.

Influenza-like illness (ILI) consultation rates, Canada, by report week, 2007-2008 compared to 1996/97 through to 2006/07 seasons

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons).

Number of New Outbreaks in Long Term Care Facilities, Canada, by Report Week, 2007-2008

Please note that the above graphs may change as late returns come in.

Single Maps | Dual Maps | Animated Maps | FluWatch Reports

Definitions for the 2007-2008 season