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Public Health Agency of Canada (PHAC)
Canada Communicable Disease Report

Volume 26-06
15 March 2000

[Table of Contents]

  

RESPIRATORY VIRUS SURVEILLANCE

FluWatch Project

Introduction

The FluWatch program provides a national picture of influenza activity across Canada during the influenza season. This article provides a brief summary FluWatch's fourth season up to and including 12 February 2000.

Methods

FluWatch reports include data and information from four main sources: (1) laboratory reports of positive influenza tests in Canada; (2) sentinel physician reporting of influenza-like illness (ILI); (3) provincial and territorial assessment of influenza activity based on various indicators, including laboratory surveillance, ILI reporting, school and work site absenteeism, and outbreaks; (4) World Health Organization (WHO) and other international reports of influenza activity. Results Across Canada, 29 laboratories submit respiratory virus detection data on a weekly basis to the Laboratory Centre for Disease Control (LCDC). Since 4 September 1999, LCDC has received reports on 38,836 influenza tests, of which 6,315 (16%) tested positive: 6,296 (99.7%) for influenza A and 19 (0.3%) for influenza B. The provincial distribution of positive tests is as follows: Newfoundland (57), Prince Edward Island (12), Nova Scotia (152), New Brunswick (88), Quebec (1,341), Ontario (2,586), Manitoba (226), Saskatchewan (380), Alberta (1,086), and British Columbia (330). Influenza B has been isolated in three provinces - Ontario (2), Saskatchewan (3), and Alberta (14). To date, 367 influenza isolates have been sub-typed by the Bureau of Microbiology, LCDC; 343 were A/Sydney/5/97-like, 20 were A/New Caledonia/20/99 (H1N1)-like, and four were B/Beijing/184/93-like.

FluWatch has 388 sentinel physicians and sentinel clinics representing 82% (236/288) of census divisions throughout Canada. Weekly ILI rates were stable at baseline levels during the autumn months and began to rise in early December, peaking in early January and then falling to baseline levels in early February. Figure 1 shows the Canadian age-standardized ILI rates for the 4 years of the FluWatch program. Figure 2 shows the cumulative ILI rates (sum of reported ILI cases in the province/sum of reported patient visits in a province x 1,000) for each province since 10 October 1999. Prince Edward Island, Newfoundland, Saskatchewan, and Manitoba have the highest cumulative ILI rates this season while British Columbia and Alberta had the lowest cumulative ILI rates. Widespread influenza activity began in early December in parts of Ontario and Alberta, and peaked during the first 2 weeks of January in regions in New Brunswick, Ontario, Manitoba, Saskatchewan, British Columbia, and the Northwest Territories. By mid-February, no widespread activity was reported in any regions. Figure 3 shows the number of influenza surveillance regions reporting localized and widespread influenza activity by report week.

Figure 1 Canadian age-standardized ILI rate by report week, 1996-1997 to 1999-2000

Figure 1 Canadian age-standardized ILI rate by report week, 1996-1997 to 1999-2000

Figure 2 Cumulative ILI rates for each province, 16 October 1999 to 12 February 2000

Figure 2 Cumulative ILI rates for each province, 16 October 1999 to 12 February 2000

Figure 3 ILI activity level in Canada, by report week, 16 October 1999 to 12 February 2000

Figure 3 ILI activity level in Canada, by report week, 16 October 1999 to 12 February 2000

In the United States, the percentage of overall patient visits for ILI peaked at 6% during the last week of December. Of the 337 isolates characterized, 306 (91%) are A/Sydney/05/97-like. Of interest, only five isolates have been subtyped as H1N1; three of these were characterized as A/New Caledonia/20/99-like(1).

The WHO has reported widespread influenza activity throughout most of the northern hemisphere, with the predominant circulating influenza subtype as A(H3N2)(2).

The composition of the vaccine for the 2000-2001 influenza season in the Northern hemisphere was announced by the WHO on 16 February 2000. The vaccine will contain the following:

  • A/Moscow/10/99(H3N2)-like virus*
  • A/New Caledonia/20/99(H1N1)-like virus
  • B/Beijing/184/93-like virus**(3).

FluWatch reports are published weekly and can be accessed through Health Canada's FluWatch Web site <http://www.phac-aspc.gc.ca/fluwatch/index.html>.

References

  1. CDC. Influenza summary update (for the week ending February 12, 2000 - week 6). URL: <http://www.cdc.gov/ncidod/diseases/flu/weeklyarchives/weekly06.htm>. Date of access: 28 Feb. 2000.

  2. World Health Organization. Global influenza surveillance - FluNet. URL: <http://rhone.b3e.jussieu.fr/flunet/www/>. Date of access: 28 Feb. 2000.

  3. World Health Organization. Recipe for the northern hemisphere flu vaccine. URL: <http://www.who.int/inf-pr-2000/en/pr2000-08.html>. Date of access: 28 Feb. 2000.

Source: S Squires, MSc, B Winchester, BSc, MSc, Division of Respiratory Diseases; P Zabchuk, Division of Disease Surveillance; Y Li, PhD, Bureau of Microbiology; M Vanderkloot, BA; T Tam MD, L Pelletier, MD, MPH, Division of Respiratory Diseases, LCDC.

* A/Panama/2007/99 is an A/Moscow/10/99(H3N2)-like virus.
** The most widely used vaccine virus is B/Yamanashi/166/98.

 

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