June 21, 2009 to June 27, 2009 (Week 25)

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Pandemic (H1N1) 2009 virus Surveillance and Epidemiology

As of 2 July, 2009, all provinces and territories have reported a total of 8,195 laboratory-confirmed cases of Pandemic H1N1 2009 virus, of which 622 H1N1 cases were admitted to hospital. Cases were distributed similarly between males and females (51.5% for males, 47.7% for females, 0.8% unknown). One-hundred and three cases have been identified as First-Nations (MB 88 cases, BC 13 cases, SK 2 cases) and 323 cases are from Nunavut, an area with a predominant Inuit population. The median age for this group (First-Nations and Innuit) was 11 years (range <1 to 79 years) as compared to 18 years (range <1 to 97 years) for the rest of the cases in Canada.

A total of 622 hospitalized cases were hospitalized. The geographic breakdown of cases was as follows: British Columbia (1.0%), Alberta (5.5%), Saskatchewan (1.5%), Manitoba (13.4%), Ontario (22.2%), Quebec (50.5%), Nova Scotia (0.6%) and Nunavut (5.3%). Core data are available for 459 (73.8%) cases. The median age of the hospitalized cases was 18 years (range <1 to 97 years). Seventy-four (16.1%) of the hospitalized cases were reported to have been admitted to the intensive care unit (ICU). Information on underlying conditions was available from 126 cases of which 73% had one or more underlying conditions: chronic heart disease (17 cases), diabetes (32 cases), kidney disease (52 cases), immune suppression (22 cases), lung disease (36 cases). Eleven women were pregnant. Among the 28 cases that died, age information was available for 22 cases. Theses cases were in the following age groups : 10 to 19 years (9.1%), 20 to 29 years (4.5%), 30 to 39 years (9.1%), 40 to 49 years (22.7%), 50 to 59 years (27.3%) and ≥ 60 years (27.3%).

Cumulative numbers of hospitalizations and deaths among Pandemic (H1N1) 2009 virus confirmed cases, Canada, to 2 July 2009

Province/Territory	Cumulative hospitalized cases	Cumulative deaths
BC	7	0
AB	34	1
SK	9	2
MB	83	2
ON	138	10
QC	314	12
NB	0	0
NS	4	0
PE	0	0
NL	0	0
YT	0	0
NT	0	0
NU	33	0
Canada	622	27

Overall Influenza Summary

During week 25, ILI consultations rates (34 consultations per 1,000 visits) and proportion of influenza positive tests (20.8%) remain high for the fifth consecutive week.

Six regions in AB, SK, ON and NU reported localized activity, 34 regions in BC, SK, MB, ON, QC, NB, NS, PEI & NU reported sporadic activity and 7 regions in NB, NS & YK reported no activity (one region in ON did not report). Three new influenza outbreaks were reported this week; one in a LTCF (AB), one in school (AB) and one occured in an unspecified location (NU). Despite numerous reports of localized activity, only one influenza outbreak was reported in Long-term care facilities.

Map of overall Influenza activity level
by provinces and territories, Week 25 Canada

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 reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.

Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2008-2009 (N=54)

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

Number of New Outbreaks in Long Term Care Facilities, Canada, by Report Week, 2008-2009

ILI consultation rate

This week, the ILI consultation rate was 34 consultations per 1,000 patient visits (see ILI graph) which represents a slight decrease relative to the two previous weeks. The sentinel response rate was 75.0%.

Influenza-like illness (ILI) consultation rates, Canada, by report week,
2008-2009 compared to 1996/97 through to 2007/08 seasons

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

Paediatric Influenza Hospitalizations and deaths

In week 24, ninety-seven laboratory-confirmed influenza-associated paediatric hospitalizations were reported through the Immunization Monitoring Program Active (IMPACT) network from AB, SK, MB, ON & QC. Forty-nine (50.5%) cases were due to H1N1 flu virus this week (57% were between age 5 to 16). To date this season, 826 hospitalizations have been reported. influenza A. The proportion of cases to date by age group are as follows: 12.7% were 0-5 month olds; 23.1% were 6-23 month olds; 21.3% were 2-4 year olds; 20.1% were 5-9 year olds; and 22.8% were 10-16 year olds. The distribution of cases to date by province are as follows: 5.7% from BC, 7.1% from AB, 2.8% from SK, 11.0% from MB, 27.4% from ON, 44.3% from QC, 1.5% from NS & 0.2% from NL.

*Due to technical reporting difficulties at PHAC, IMPACT for week 25 is not available.

Laboratory Surveillance Summary

This week, the proportion of tests that were positive for influenza was 20.8% which is still high but has decreased from the peak seen two weeks ago. The majority (79.7%) of influenza virus detections this season have been for influenza A. 99.6% of influenza virus detections this week have been for influenza A likely due to the Pandemic H1N1 2009 virus.

Total number of influenza tests performed and number of positive tests
by province/territory of testing laboratory, Canada, 2008-2009

Province of reporting laboratories	Report Period: June 21, 2009 to June 27, 2009				Season to Date: August 24, 2008 to June 27, 2009
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	144	14	0	14	1499	161	26	187
PE	6	0	0	0	257	17	9	26
NS	162	35	0	35	2552	167	60	227
NB	66	8	0	8	2379	281	95	376
QC	1188	201	2	203	44666	3559	1415	4974
ON	1801	338	3	341	49316	5818	1351	7169
MB	627	236	0	236	5425	850	37	887
SK	554	184	0	184	9110	1163	219	1382
AB	2415	400	1	401	41755	2198	466	2664
BC	121	54	0	54	7664	1071	210	1281
Canada	7084	1470	6	1476	164623	15285	3888	19173

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.

Influenza tests reported and percentage of tests positive, Canada,
by report week, 2008-2009

Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2008-2009

Influenza Tests Received from Provincial Labs with subtyping capacity, Canada, 2008-2009

Reporting provinces	Influenza A					Influenza B
	Total	A(H1)	A(H3)	A(H1N1 flu virus)	A(not subtyped)
BC	1071	9	6	152	904	210
AB	2198	0	8	231	1959	466
SK	1163	28	78	673	384	219
MB	850	7	35	553	255	37
ON	5818	144	135	2636	2903	1351
QC	3559	0	0	0	3559	1415
NB	281	3	3	4	271	95
NS	167	23	23	64	57	60
PE	17	3	0	0	14	9
NL	161	11	4	23	123	26
Canada	15285	228	292	4336	10429	3888

Antigenic Characterization
Since 1 September 2008, the NML has antigenically characterized 978 influenza viruses: 243 influenza A/Brisbane/59/2007(H1N1)-like (from BC, AB, SK, MB, ON, QC, NB, NS & PEI), 168 influenza A/Brisbane/10/2007(H3N2)-like (from BC, AB, SK, MB, ON, QC, NB, NS, PEI & NL), 11 influenza B/Florida/4/2006-like (from AB, ON, QC & NB), 177 B/Brisbane/60/2008-like (from BC, AB, SK, MB, ON, QC, NB, NL & NU) and 379 B/Malaysia/2506/2004-like (in all provinces except the Territories). A/Brisbane/59/2007(H1N1), A/Brisbane/10/2007(H3N2) and B/Florida/04/2006 are the influenza A and influenza B components recommended for the 2008-09 influenza vaccine. All influenza A isolates are a good match to this season’s influenza vaccine while only 11/567 (1.9%) of influenza B viruses match this season’s vaccine. As of 2 July, 2009 the NML tested 656 specimens for Pandemic (H1N1) 2009 virus and 364 were positive. Positive samples were from AB, SK, MB, ON, QC, NB, NS, PEI and NL.

*Provincial labs are also doing their own confirmation using RT-PCR.

Antiviral Resistance (from NML)

All Pandemic (H1N1) 2009 viruses tested so far have been sensitive to oseltamivir (208 samples) and zanamivir (91 samples) but resistant to amantadine (208 samples).

International update:

Southern Hemisphere
As of July 2nd, 2009, five Southern hemisphere countries reported over 500 cases of Pandemic (H1N1) 2009 influenza: Chile (7,376 cases, 14 deaths), Australia (4,568 cases, 9 deaths), Argentina (1,587 cases, 26 deaths), and New Zealand (825 cases), Brazil (737 cases), and Peru (549 cases). In the majority of deaths, patients had significant underlying illness such as cancer. Chile reports a 200% increase in pediatric hospitalizations over last year, with an unexpected increase in hospitalizations for RSV <http://www.minsal.cl/> . Argentina has called for nationwide school closures to prevent the spread of influenza [source GPHIN]. Overall, South American countries now report 11,490 cases (up 31% from last week) and 46 deaths (up 41%).

Although the number of cases is still small, South Africa reported 13 new cases this week for a total of 14. No community transmission is reported. Seasonal influenza surveillance to June 21st, shows that 91.7% (851/928) of subtyped influenza isolates were A(H3N2).

• NICD <http://www.nicd.ac.za/>

Northern Hemisphere
CDC: During week 25 (June 21-27, 2009), influenza activity decreased in the United States, however, there were still higher levels of influenza-like illness than is normal for this time of year. 2,165 (99.8%) specimens tested positive for influenza Pandemic H1N1 2009. Two-hundred and two samples of H1N1 2009 virus were tested for antiviral resistance. None were resistant to oseltamivir or zanamivir. Of 177 samples tested for resistance to adamantanes, 100% were resistant. Eight influenza -associated pediatric deaths were reported during week 25 due to influenza A; seven with Pandemic H1N1 2009 virus and one with influenza A virus. The deaths reported this week occurred between June 6-27, 2009. Bacterial co-infections were observed in 14 (37.8%) of children and Staphylococcus aureus was identified in nine (64.3%) of 14 children tested.

• CDC <http://www.cdc.gov/flu/weekly/>

EISS: Since the last FluWatch report, the United Kingdom has reported 4,024 new cases of Pandemic (H1N1) 2009 and two new deaths for a total of 6,929 cases (up 58%) and 3 deaths. Five European countries with between 50 and 350 cases of H1N1 2009 each reported new cases accounting for >40% of their total cases in the past week: Cyprus (58 cases, up 91%), Switzerland (65 cases, up 49%), Greece (109 cases, up 47%), France (311 cases, up 45%), and Denmark (57 cases, up 40%). Three countries reported their first cases since the last FluWatch report: Serbia (13), Guernsey (UK Crown Dependency) (5) and Lithuania (3). EU/EEA countries: Seventy-five percent of cases are reported in children and young adults under 30 years of age; Respiratory symptoms were reported from 89% of symptomatic cases; Gastro-intestinal symptoms were reported from 14% of symptomatic cases. All pandemic H1N1 viruses have been susceptible to zanamivir and resistant to M2 inhibitors, while only a single case of oseltamivir resistance has been reported in Denmark.

• EISS <http://www.euroflu.org/cgi-files/bulletin_v2.cgi>

Human Avian Influenza: During week 25 (June 21-27, 2009), the WHO reported no new case of H5N1 avian influenza infection.

• WHO

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FluWatch reports include data and information from five main sources: laboratory reports of positive influenza tests in Canada; sentinel physician reporting of influenza-like illness (ILI); provincial/territorial assessment of influenza activity based on various indicators, including laboratory surveillance, ILI reporting, school and work site absenteeism, and outbreaks; influenza-associated pediatric hospitalizations; WHO and other international reports of influenza activity.
The map shows influenza activity in the “influenza surveillance regions” † within each jurisdiction, as determined by the provincial/territorial epidemiologists.

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).

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Definitions for the 2008-2009 season