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Reporting Week 9

Sunday, February 25, 2018 to Saturday, March 3, 2018


New Cases
 
53 New influenza cases reported to the Health Department in week nine
This is a decrease compared to the number of cases in week eight (56 cases reported in week eight)
Influenza activity for the 2017/18 season was generally on the rise until week six and we have since seen a decrease in recent weeks. The majority of the confirmed influenza cases this season have been among older adults aged 65 and over. 
Figure 1: Total number of influenza cases to date, by age group, 2017/18 influenza season, Halton Region
Total Cases
 
532 Influenza cases reported to the Health Department in the 2017/18 season
 
A
 
274 cases of influenza A (subtypes: (H1N1)pdm09 (6), H3 (58), not subtyped (210))
B
 
258 cases of influenza B
Emergency Department
 
6.2% of ED visits were classified as respiratory during week nine
 
This is a decrease compared to the percentage of ED visits classified as respiratory during week eight (7.9%)
There has been an overall increase in the percentage of all ED visits for a respiratory complaint since the start of the 2017/18 season, but in recent weeks we have started to see a decrease. The peak seen in week 52 may be associated with closures to physician's offices during the holidays. 
Figure 2: Percentage of all ED visits for a respiratory complaint among Halton residents, by reporting week, 2017/18 influenza season, Halton Region

Flu Activity

Localized
 
There was localized flu activity reported in Halton Region during week nine
It’s not too late to get the flu shot! For more information and to find a clinic near you, visit our influenza webpage at halton.ca/flu
For information on influenza activity in Ontario, please see Public Health Ontario’s Respiratory Pathogen Bulletin.
For information on influenza activity in Canada, please see the Public Health Agency of Canada's FluWatch. 

Data Notes

Many cases of influenza are not diagnosed or reported to the Halton Region Health Department because infected individuals may not seek medical attention, or when physicians are visited they often do not order laboratory confirmation because it is unnecessary in uncomplicated situations when influenza is known to be circulating. Data provided in this report reflect only those cases that had laboratory confirmation of influenza infection. The actual number of cases in the community is likely to be much higher than the number presented in this report. 

In contrast to the common cold, symptoms of influenza are more sudden in onset and more severe (fever, sore throat, headache, muscle ache, profound fatigue, cough), especially in the very young or old, or individuals with compromised immune systems. In children, nausea, vomiting, and diarrhea are not uncommon. Symptoms usually resolve in five to seven days, however, monitoring influenza is important due to how quickly epidemics evolve the widespread morbidity, and the seriousness of complications, notably viral and bacterial pneumonias.

Influenza Activity Level Definitions:

No activity – no laboratory-confirmed cases of influenza reported and no ongoing laboratory-confirmed institutional influenza outbreaks

Sporadic – at least one laboratory-confirmed case of influenza with no ongoing laboratory-confirmed institutional influenza outbreaks

Localized – at least one ongoing laboratory-confirmed influenza outbreak in an institution

Widespread – multiple ongoing laboratory-confirmed influenza outbreaks in institutions separated by some geographic distance, in other words, non-adjacent areas

Comparisons to previous flu seasons:

Variability between flu seasons exists for many reasons, including: the strains of influenza that are circulating; how well matched the flu vaccine was to the circulating strains; which age groups are most affected; and the severity of illness resulting from infection. In addition, many cases of influenza go unreported, laboratory confirmation is not necessary in uncomplicated cases, and changes to laboratory testing algorithms over time may have altered the percent of samples that are tested for influenza. Recent changes have also occurred in the requirements for laboratory-confirmed influenza case follow up. For the 2017/18 season, there is no longer a provincial requirement for PHU's to follow up any laboratory-confirmed influenza cases. For these reasons it is not recommended to compare the current flu season to previous flu seasons.

Data Source 

iPHIS - This report uses data from iPHIS. iPHIS is a dynamic disease reporting system which allows ongoing updates to data previously entered. As a result, data extracted from iPHIS represent a snapshot at the time of extraction and may differ from previous or subsequent reports.

ACES - This report uses emergency department visit data from the Acute Care Enhanced Surveillance (ACES) Application.

For more information on influenza activity in Ontario please visit the Influenza-Like Illness (ILI) Mapper and the Ontario Respiratory Pathogen Bulletin.

Last updated: Tuesday, March 6, 2018 

Copyright © 2018 Halton Region Health Department, All rights reserved.


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