June 14, 2009 to June 20, 2009 (Week 24)

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H1N1 flu virus Surveillance and Epidemiology

As of 25 June, 2009, all provinces and territories have reported a total of 6,906 laboratory-confirmed cases of H1N1 flu virus, of which 460 H1N1 cases were admitted to hospital. Cases were distributed similarly between males and females (51.4% for males, 48.1% for females, 0.5% unknown). These hospitalized cases were from British Columbia (1.1%), Alberta (5.0%), Saskatchewan (1.5%), Manitoba (16.3%), Ontario (17.8%), Quebec (53.7%), Nova Scotia (0.2%) and Nunavut (4.4%). Of the 460 hospitalized cases, core data are available for 366 (79.6%) cases. The median age of the hospitalized cases was 17 years (range <1 to 82 years). Sixty-nine (18.6%) of the hospitalized cases were reported to have been admitted to the intensive care unit (ICU). Information regarding underlying medical conditions was available for 94 hospitalized cases. Among theses, 35 cases (37%) have underlying medical conditions, including lung disease (9), diabetes (3), kidney disease (2), immune suppression (4) and chronic heart disease (6), and other underlyings conditions (20) (note that 10 cases reported more than one underlying condition). Three hospitalized cases were pregnant women, all in their 3rd trimester. Among the twenty-one deaths reported as of June 25, 2009, we have information for nineteen of them. These nineteen deaths are in the following age groups : 10 to 19 years (n=2, 10.5%), 20 to 29 years (n=1, 5.2%), 30 to 39 years (n=2, 10.5%), 40 to 49 years (n=4, 21.1%), 50 to 59 years (n=6, 31.6%) and ≥ 60 years (n=4, 21.1%). Thirteen (38.4%) had medical underlying conditions. The 13 deaths with underlying medical conditions reported lung disease (4), diabetes (4), heart disease (2), hypertension (1) and other underlying conditions (2) (note that some cases reported more than 1 underlying condition).

Weekly and cumulative numbers of hospitalizations and deaths due to H1N1 flu virus, Canada,
to 25 June 2009

Province/Territory	This week  (18-25 June, 2009) hospitalized cases	This week  (18-25 June, 2009) deaths	Cumulative hospitalized  cases	Cumulative deaths
BC	0	0	5	0
AB	15	0	23	1
SK	0	0	7	0
MB	32	0	75	2
ON	28	5	82	7
QC	87	4	247	11
NB	0	0	0	0
NS	0	0	1	0
PE	0	0	0	0
NL	0	0	0	0
YT	0	0	0	0
NT	0	0	0	0
NU	5	0	20	0
Canada	167	9	460	21

Overall Influenza Summary

Overall influenza activity is still high this week, in particular for rates of visits to healthcare professionals for ILI consultations (42 consultations par 1,000 visits) and proportion of tests positive for influenza (19.2%).

Nine regions in AB, SK, MB, ON, NL & NU reported localized activity, 31 regions sporadic activity in BC, AB, SK, MB, ON, QC, NB, NS, NL, NT & NU and 13 regions in NB, NS, PE, NL, YK & NT reported no activity (no report received from 1 region in ON). Six new influenza outbreaks were reported this week; three were in hospitals (NL), one in LTCF (AB) and two occured in unspecified locations (MB). Despite numerous reports of localized activity, influenza outbreaks are not being reported in Long-term care facilities.

Map of overall Influenza activity level
by provinces and territories, Week 24 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 increased to 42 consultations per 1,000 patient visits (see ILI graph) which is comparable to the level observed during the seasonal influenza peak (week 9). The sentinel response rate was 82.9%.

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; 54.8% of hospitalizations have been due to 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.

Laboratory Surveillance Summary
This week, the proportion of tests that were positive for influenza was 19.2% which is higher than expected for this time of the year (see table). The majority (76.6%) of influenza virus detections this season have been for influenza A. 99.5% of influenza virus detections this week have been for influenza A likely due to the H1N1 flu 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 14, 2009 to June 20, 2009				Season to Date: August 24, 2008 to June 20, 2009
	Total # Influenza Tests	# of Positive Tests			Total # Influenza Tests	# of Positive Tests
		Influenza A	Influenza B	Total		Influenza A	Influenza B	Total
NL	97	19	0	19	1355	147	26	173
PE	12	0	0	0	251	17	9	26
NS	134	24	0	24	2390	132	60	192
NB	40	5	0	5	2313	273	95	368
QC	1918	289	0	289	43450	3354	1413	4767
ON	2853	468	2	470	47515	5480	1348	6828
MB	701	221	0	221	4798	614	37	651
SK	782	274	0	274	8556	979	219	1198
AB	1626	339	3	342	39340	1798	465	2263
BC	241	51	2	53	7543	1017	210	1227
Canada	8404	1690	7	1697	157511	13811	3882	17693

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	1017	8	6	102	901	210
AB	1798	0	8	137	1653	465
SK	979	23	78	518	360	219
MB	614	7	35	317	255	37
ON	5480	144	135	2588	2613	1348
QC	3354	0	0	0	3354	1413
NB	273	3	3	1	266	95
NS	132	23	23	30	56	60
PE	17	3	0	0	14	9
NL	147	11	4	9	123	26
Canada	13811	222	292	3702	9595	3882

Antigenic Characterization
Since 1 September 2008, the NML has antigenically characterized 976 influenza viruses: 242 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), 176 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 11/566 (1.9%) of influenza B viruses match this season’s vaccine. As of 26 June, 2009 the NML tested 585 specimens for influenza H1N1 flu virus and 317 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)
Oseltamivir: 302/303 A/H1N1 isolates were resistant (99.7%). Zanamivir: All A/H1N1 isolates tested were sensitive (0%). Adamantanes: 359/359 A/H3N2 isolates were resistant to amantadine (100%). All H1N1 flu viruses tested so far have been sensitive to oseltamivir (149 samples) and zanamivir (68 samples) but resistant to amantadine (207 samples).

International update:

Southern Hemisphere
Countries of the Southern hemisphere in descending order of number of confirmed cases of Pandemic A(H1N1) 2009 – and associated deaths, including pneumonia: Chile (5186 – 7), Australia (3280 – 3), Argentina (1294 – 17), Brazil (399), New Zealand (386), Peru (225), Uruguay (195), Ecuador (115), Paraguay (79), Colombia (71), Bolivia (44). Countries reporting a single case: Papua New Guinea, Samoa, Vanuatu, French Polynesia (FOC), South Africa. In Australia, of the three patients who died with Pandemic A(H1N1) infection, all had underlying medical conditions. In Chile, children between 5-19yrs have been most affected, constituting 61% of cases. Age range of cases: 1-93yrs, Median: 13yrs. In Brazil, of 271 confirmed cases, 50% have been under 27yrs. Age range: 1-65yrs. (Based on national and regional data reported June 23-26, 2009.)

Northern Hemisphere
CDC: During week 23 (June 7-13, 2009), 38.7% of specimens for ILI tested positive for influenza. Over 82% of all subtyped influenza A viruses being reported to CDC were H1N1 flu virus. The proportion of deaths attributed to pneumonia and influenza (P&I) was slightly above the epidemic threshold. One influenza-associated pediatric death was reported and was associated with pandemic influenza A (H1N1) virus infection in week 23, bringing the total to 71 pediatric deaths. In total, 18 of 52 jurisdictions reported regional or widespread influenza activity.

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

As of June 18th, 2009, the CDC reported 21,449 cases of H1N1 flu virus in the United States, including 87 deaths.

• CDC < http://www.cdc.gov/h1n1flu/update.htm >

EISS: As of June 25th, 2009, the European Influenza Surveillance System (EISS) reported 4,947 cases in 28 countries, with 1 death (in the UK). 101 of these cases reported in the previous 24hrs from 11 countries, with France reporting the most new cases (41). Top 10 countries in descending order of number of confirmed cases: UK (3254), Spain (541), Germany (333), France (191), Netherlands (112), Italy (102), Greece (66), Sweden (61), Denmark (37), Belgium (35).

• EISS <http://www.ecdc.europa.eu/en/files/pdf/Health_topics/Situation_Report_090625_1700hrs.pdf>

Other regions : As of June 24th, 2009, based on data from the WHO, the top 10 countries of the Asian continent and middle-East in descending order of number of confirmed cases of Pandemic A(H1N1) 2009: China (906), Japan (893), Thailand (774), Philippines (445), Israel (375), Singapore (194), Republic of Korea (115), Malaysia (68), India (64), VietNam (56).

 

 

Human Avian Influenza: During week 23, 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