Volume 24-04
15 February 1998

[Table of Contents]

RESPIRATORY VIRUS SURVEILLANCE - FluWatch Project

FluWatch, Canada's influenza surveillance program, now in its second season, began on 15 October 1997. The program collects, synthesizes, and reports data from four main sources: sentinel physician reporting of influenza-like illness (ILI); provincial and territorial assessments of influenza activity based on various indicators, including physician reporting and sickness absence data; laboratory reports of positive influenza tests; and World Health Organization and other international reports of influenza activity. ILI is defined as an acute febrile (fever and or chills) respiratory illness characterized by one or more of the following: cough, sore throat, arthralgia, myalgia, or prostration which, in the opinion of the attending physician, could be due to influenza virus. This update summaries influenza activity until 21 January 1998.

This year FluWatch has enrolled 200 sentinel physicians representing 131/288 (46%) census divisions in Canada. The physician response rate varies by province and by week. The mean response rate is 53% (29% to 68%). Figure 1 illustrates the standardized rates of ILI by province for this season's FluWatch. Newfoundland, Saskatchewan, and Alberta have had the highest rates to date. The standardized rates of ILI reported to FluWatch (Figure 2) during the current season are relatively constant, and do not show the peak in activity over the holiday season that was observed for the 1996-1997 season. The highest rate of ILI, to date, has been in the < 10-year-old age group (115 per 1,000 patients seen).

The first influenza isolate this season was identified as A/Wuhan/359/95(H3N2), and was submitted by Quebec. As of 16 January, 1998 we have received reports on 11,110 laboratory tests for influenza. Of these, 226 are confirmed as influenza A and four as influenza B. The distribution of influenza A is as follows: Nova Scotia (6); New Brunswick (2); Quebec (73); Ontario (134); Manitoba (6); Alberta (2); and British Columbia (3). FluWatch reports, published every 2 weeks, can be accessed through the FluWatch Website: http://www.phac-aspc.gc.ca/fluwatch/index.html.

Figure 1 Standardized rates of ILI across Canada, by province, reported to FluWatch, 15 October 1997 - 20 January 1998

Figure 2 Standardized rates of reported ILI across Canada, by week, reported to FluWatch, 15 October 1996 - 20 January 1997 and 15 October 1997 - 20 January 1998

Influenza A(H5N1) ("bird flu" or "avian flu") is a newly discovered virus affecting humans, previously known to infect only birds. It was first isolated from a human case in Hong Kong in 1997. As of 19 January, 1998 there were 18 confirmed human cases, with six deaths and one suspected case, all residents of Hong Kong Special Administrative Region. The onset date of the last confirmed case was 28 December, 1997. Up-to-date information can be obtained from the Hong Kong Department of Health Website: http://www.info.gov.hk/dh/new/bullet.htm.  Information can also be obtained from the Infectious Diseases News Brief Website: http://www.phac-aspc.gc.ca/bid-bmi/dsd-dsm/nb-ab/index.html.

Source:

P Buck, DVM, MSc, Field Epidemiologist, S Herman, C Scott, B Winchester, BSc, MSc, P Zabchuk, P Sockett, PhD, Chief, Division of Disease Surveillance, Bureau of Infectious Diseases; M Vanderkloot, BA, Bureau of Surveillance and Field Epidemiology, LCDC, Ottawa,ON. Our mission is to help the people of Canada maintain and improve their health. Health Canada

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