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North American Flu Surveillance: Week 7

 

 


# 5340

 

 

Influenza activity in the United States remains elevated, while in Canada – where levels had been declining for several weeks -  the number of new influenza cases is on the rise again.

 

A few excerpts from week 7’s data (ending Feb 19th) -pulled from the latest CDC’s FluView and PHAC’s  FluWatch  surveillance reports.

 

In Canada:

 

Summary of FluWatch Findings for the Week ending February 19, 2011

  • In week 07, there was an increase in overall influenza activity level, with 62.5% (35/56) of regions reporting localized influenza activity. There was a substantial increase in the number of outbreaks reported this week. The proportion of positive influenza detections overall decreased slightly, though the ILI consultation rate remained similar to the previous week.
  • Since the beginning of the season, 86.3% of the subtyped positive influenza A specimens have been influenza A/H3N2. In week 07, pandemic H1N1 2009 detections increased to 8% of positive influenza detections while the proportion of influenza B detections remained stable at 10%.

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Overall Influenza Summary – Week 7 (February 13 to February 19, 2011)

In week 07, 35 regions reported localized activity (in all provinces except PE), 15 regions reported sporadic activity (in all provinces and territories except YK) and 6 regions presented no activity (see Activity level Map).

Compared to the previous week (week 06), 15 regions reported an increased level of influenza activity, 5 regions reported decreased activity, and 33 regions maintained a stable level of influenza activity (sporadic or higher).

Fifty-one new ILI/influenza outbreaks were reported: 26 in long-term care facilities (LTCF) in BC(2), SK (5), ON(4), QC(7), NB (2) and NS(6); 20 school outbreaks in AB(2), NB(15), NS(1) and NL(2); 1 hospital outbreak in ON; and 4 outbreaks in other facilities in SK(1), ON(2) and NL(1).

 

 

From the CDC, a few excerpts from this week’s FluView report.

 

 

2010-2011 Influenza Season Week 7 ending February 19, 2011

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Synopsis

During week 7 (February 13-19, 2011), influenza activity in the United States remained elevated.

  • Of the 9,154 specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division, 2,866 (31.3%) were positive for influenza.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) was above the epidemic threshold for the fourth consecutive week.
  • Six influenza-associated pediatric deaths were reported bringing to season total to 41. Three of these deaths were associated with an influenza B virus, one was associated with an influenza A (H3) virus, one was associated with a 2009 influenza A (H1N1) virus, and one was associated with an influenza A virus for which the subtype was not determined.
  • The proportion of outpatient visits for influenza-like illness (ILI) was 4.9%, which is above the national baseline of 2.5%. All 10 regions reported ILI above region-specific baseline levels. Twenty-one states experienced high ILI activity; six states experienced moderate ILI activity; New York City and 16 states experienced low ILI activity; seven states experienced minimal ILI activity, and the District of Columbia had insufficient data.
  • The geographic spread of influenza in 44 states was reported as widespread; four states reported regional influenza activity; the District of Columbia reported local influenza activity; Puerto Rico, the U.S. Virgin Islands, and two states reported sporadic influenza activity, and Guam reported no influenza activity.

U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories located in all 50 states and Washington D.C. report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza type and subtype. The results of tests performed during the current week are summarized in the table below.

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Pneumonia and Influenza (P&I) Mortality Surveillance

During week 7, 8.3% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was above the epidemic threshold of 8.0% for week 7 and is the fourth consecutive week in which P&I has been above the epidemic threshold.

Pneumonia And Influenza Mortality

Influenza-Associated Pediatric Mortality

Six influenza-associated pediatric deaths were reported to CDC during week 7. Three of these deaths were associated with an influenza B virus, one was associated with an influenza A (H3) virus, one was associated with a 2009 influenza A (H1N1) virus, and one was associated with an influenza A virus for which the subtype was not determined. Forty-one deaths from 21 states (Arizona, Colorado, Florida, Georgia, Illinois, Indiana, Louisiana, Michigan, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Pennsylvania, Texas, Utah, Virginia, West Virginia, and Wisconsin) and New York City have been reported during this influenza season.

Sixteen of the 41 deaths reported were associated with influenza B viruses, 10 deaths reported were associated with influenza A (H3) viruses, eight were associated with 2009 influenza A (H1N1) viruses, and seven were associated with an influenza A virus for which the subtype was not determined.

Influenza-Associated Pediatric Mortality

Related Post:

Influenza Activity
FluView

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