Canada: Influenza activity appears to be decreasing across the country, except in Ontario and one region of Alberta where widespread influenza activity is reported. Localized activity is reported in Quebec, parts of British Columbia, Manitoba, New Brunswick, and Nova Scotia, while the rest of the country reports either sporadic or no activity. During the week ending March 12, 2005 (week 10), sentinel physicians reported 47 cases of influenza-like illness (ILI) per 1000 patient visits. see ILI graph. Over the one week period, the Public Health Agency of Canada received 3865 reports of laboratory tests for influenza, including 385 (10.0%) influenza A detections and 151 (3.9%) influenza B detections(see table below). During this week, 67 new influenza outbreaks were reported, 51 (76%) of which were reported in Ontario. To date this season, there have been a total of 947 influenza outbreaks, of which 694 were reported in LTCF/ retirement lodges, 72 in hospitals and 181 in schools. The National Microbiology Laboratory (NML) has antigenically characterized 775 influenza viruses: 688 influenza A (H3N2) and 87 influenza B viruses. Of the 688 influenza A (H3N2), 503 (73%) were A/Fujian/411/02(H3N2)-like and 185 (27%) A/California/7/04-like viruses. Of the 87 influenza B, 73 were B/Shanghai/361/02-like and 14 B/Hong Kong/330/2001-like virus. From February 17 to March 16 2005, the NML had characterized 268 influenza A viruses, of which A/California represented 69% of isolates.

During the one week period from March 6 to March 12, 10 reports of laboratory confirmed influenza-associated hospitalizations in 11 centres were reported through the IMPACT (Immunization Monitoring Program Active) network. One influenza-associated pediatric death has been reported this season. Since October 9th 2004, there have been a total of 314 reports, of which children aged 0 to 23 months accounted for the highest proportion (56%). Influenza A is the predominant virus type in these reports.

Avian Influenza: On March 11th 2005, WHO reported an additional ten human cases with H5N1 infection in Viet Nam, including some recent cases and some retrospective older cases. Of the newly reported cases, three have been fatal. WHO is awaiting further details about these cases. A total of 69 cases of human H5N1 infection, of which 46 were fatal have been reported since January 2004. Rapid field investigation of each new case is essential to ensure timely detection of clusters of cases occurring in family members or health care workers.

• WHO

United States: CDC: During the week ending March 5, 2005 (week 09), influenza activity continued to decline in the US. ILI accounted for 4.0% of patient visits to sentinel physicians, which is above the national baseline of 2.5%. Sentinel cities reported 8.9% of deaths as attributable to pneumonia and influenza, which is above the epidemic threshold of 8.2% for this week. Of the 308 influenza A(H3N2) viruses characterized this season, 171 (56%) were A/California/7/2004-like and 137 (44%) A/Fujian/411/2002-like. Fifteen influenza-associated pediatric deaths have been reported this season.

• CDC Weekly Report

International: EISS: I Influenza activity is on the rise in Scandinavia and Eastern Europe. The majority of viruses reported in Europe remains influenza A (H3), however in recent weeks the proportion of influenza B viruses is increasing, mainly in the Czech Republic, Ireland and Poland.

• EISS 
  

Total number of influenza tests performed and number of positive tests by province/territory of testing laboratory, Canada, 2004-2005

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.html>

Number of influenza surveillance regions† reporting widespread or localized influenza activity, Canada, by report week, 2004-2005 (N=52)

† 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, March 6, 2005 to March 12, 2005 (Week 10)
	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 the 2004-2005 season. 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, 2004-2005

Percent positive influenza tests, compared to other respiratory viruses by reporting week, Canada, 2004-2005

Influenza strain characterization, Canada, cumulative, 2004-2005 influenza season by the Respiratory Viruses Section at the National Microbiology Laboratory
[N=775]

NACI recommends that the trivalent vaccine for the 2004-2005 season in Canada contain A/New Caledonia/20/99 (H1N1)-like, A/Fujian/411/2002 (H3N2)-like, and B/Shanghai/361/2002-like virus antigens.
Note: Vaccine producers may use antigenically equivalent strains because of their growth properties. A/Wyoming3/2003 and A/Kumamoto/102/2002 strains are antigenically equivalent to the A/Fujian/411/2002 (H3N2); B/Jilin/20/2003 and B/Jiangsu/10/2003 virus strains are antigenically equivalent to B/Shanghai/361/2002. The vaccines to be marketed in Canada for the 2004-2005 flu season contain A/New Caledonia/20/99 (H1N1), A/Wyoming/3/2003 (H3N2) and B/Jiangsu/10/2003 virus antigens.

Influenza-like illness (ILI) reporting rates, Canada, by report week, 2004-2005 compared to 1996/97 through 2003/2004 seasons

Note: No data available for mean rate in previous years for weeks 21 to 39 (1996-1997 through 2002-2003 seasons). During weeks 20-39, 2002-2003/2003-2004 seasons, ILI is reported once every two weeks, on even weeks only

Number of Outbreaks in Long Term Care Facilities by Report Week, Canada, 2004-2005

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

Definitions for the 2004-2005 season

[FluWatch]