Friday, February 24, 2012
Middlesex London Health Unit
Influenza Activity In Middlesex-London
Since the last report, one influenza B case was reported to the Middlesex London Health Unit. To date, there have been nine influenza A cases and three influenza B cases identified in Middlesex London for the 2011-2012 influenza surveillance season. Six of the influenza A samples have been typed as human influenza A (H3). One of these samples has been strain typed as A/Perth/16/2009-like (H3N2) which is the H3N2 component for this year’s influenza vaccine.
There continues to be no outbreaks of influenza in long-term care homes or in acute care facilities. The overall proportion of patients presenting to London emergency departments and urgent care with fever and respiratory symptoms was slightly lower compared to the previous week, and school absenteeism was also slightly lower relative to the previous week. Based on the available information, influenza activity in Middlesex London remains low.
Provincial and National Influenza Activity:
Influenza: Influenza activity across the province is higher this week than compared to the previous week, but continues to be lower than in previous years. According to the latest Ontario Influenza Bulletin, there were 99 laboratory-confirmed cases of influenza reported between February 5 and 11, 2012. In total, 355 influenza cases have been reported to the province for the 2011-2012 surveillance season. The majority of the influenza cases reported were subtyped as influenza B (181 cases) or influenza A(H1N1)pdm09 (formerly known as influenza A pH1N1) (77 cases), which together account for 72.7% (258/355) of cases reported to date. Provincially, one new institutional influenza outbreak was reported between February 5 and 11; it was identified as influenza B. In total, ten institutional influenza outbreaks have been reported across the province this season, seven of which were influenza B and three influenza A (all subtypes). Nationally, influenza activity continues to increase. The percent of positive influenza B detections has been increasing nationally over the past several weeks. To date, Ontario, Quebec, and the Atlantic provinces have had the highest proportion of influenza B detections relative to influenza A detections.
To date, strain characterization of influenza isolates in Ontario and Canada has demonstrated a generally good match with this season’s influenza vaccine. Since the start of the season, the National Microbiology Lab has characterized 242 samples from across Canada with the following results: 73 Influenza A (H3N2)/Perth/16/2009-like and 48 Influenza A/California/07/2009, both of which are components of the 2011-2012 influenza vaccine; 70 influenza B strains are antigenically related to the strain B/Brisbane/60/2008, which also is a component of the 2011-2012 influenza vaccine; and the other 51 influenza B viruses are antigenically related to B/Wisconsin/01/2010-like, which belongs to a different lineage than the influenza strain B that is in this year’s vaccine.
Other Respiratory Pathogens: Provincially and nationally, the main respiratory virus being identified is Respiratory Syncytial Virus (RSV). In Ontario, from February 5 to 11, there were 38 positive results of 107 samples tested by the Ontario Public Health Laboratory, for a positivity rate of 35.5%. Nationally, the percent positivity for RSV was 19.5%, making it the most prevalent of the other non-influenza respiratory viruses being detected in the country.
Coronavirus is also a predominant circulating virus this surveillance season. In Ontario, there were 10 positive results out of 51 samples tested by the Ontario Public Health Laboratory, for a positivity rate of 19.6% for the period of February 5 to 11, 2012.
Influenza vaccination opportunities:
Influenza vaccination is available at some health care providers’ offices and at the Health Unit’s walk-in Immunization clinics. Clinics are scheduled at 50 King Street in London on Mondays, Wednesdays and Fridays from 9:00 a.m. to 4:00 p.m. and on the first and third Wednesday of each month from 9:00 a.m. to 7:00 p.m. Clinics also take place at the Kenwick Mall in Strathroy from 3:30 p.m. to 7:30 p.m. on the first Tuesday of each month.
For more detailed information, click here to see a Summary of Community Influenza Surveillance Indicators.