Avian Flu Diary: CDC FluView Week 52

# 6825

The CDC has updated their weekly FluView report, which covers influenza surveillance through December 29th, 2012. As you can see by the ILI (Influenza-like-Illness) activity map above, much of the nation is now seeing high levels of illness.

Another chart from today’s interactive FluView compares the number of outpatient ILI’s being reported with previous years, including the moderately-severe 2007-08 flu season.

Not only are ILI levels this year approaching that year’s peak, they are doing so 8 weeks earlier in the season.

How high ILI rates will go, and how long they will remain elevated, is something we’ll have to wait to see, but earlier today, the CDC released a statement saying:

. . . based on past experience it’s likely that flu activity will continue for some time. During the past 10 influenza seasons, ILI remained at or above baseline for an average of 12 consecutive weeks . . .

Here then are some excerpts from today’s FluView Week 52 report.

2012-2013 Influenza Season Week 52 ending December 29, 2012

All data are preliminary and may change as more reports are received.

Synopsis:

During week 52 (December 23-29), influenza activity increased in the U.S.

Viral Surveillance: Of 9,363 specimens tested and reported by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories, 2,961 (31.6%) were positive for influenza.

Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.

Influenza-Associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported and were associated with influenza B viruses.

Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 5.6%; above the national baseline of 2.2%. Nine of 10 regions reported ILI above region-specific baseline levels. New York City and 29 states experienced high ILI activity; 9 states experienced moderate ILI activity; 4 states experienced low ILI activity; 6 states experienced minimal ILI activity, and the District of Columbia and 2 states had insufficient data.

Geographic Spread of Influenza: Forty-one states reported widespread geographic influenza activity; 7 states reported regional activity; the District of Columbia reported local activity; 1 state reported sporadic activity; Guam reported no influenza activity, and Puerto Rico, the U.S. Virgin Islands, and 1 state did not report.

Novel Influenza A Virus:

No new human infections with novel influenza A viruses were reported to CDC during week 52.

A total of 312 infections with variant influenza viruses (308 H3N2v viruses, 3 H1N2v viruses, and 1 H1N1v virus) have been reported from 11 states since July 2012. More information about H3N2v infections can be found at http://www.cdc.gov/flu/swineflu/h3n2v-cases.htm.

Pneumonia and Influenza (P&I) Mortality Surveillance:

During week 52, 7.0% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.1% for week 52.

Influenza-Associated Pediatric Mortality:

Two influenza-associated pediatric deaths were reported to CDC during week 52 and were associated with influenza B viruses. One death occurred during week 48 (week ending December 1) and one death occurred during week 52 (week ending December 29). This brings the total number of influenza-associated pediatric deaths reported during the 2012-2013 season to 18. Additional data can be found at http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

And finally, a mash-up of a chart showing Laboratory Confirmed Influenza Hospitalizations by age group, we see that (not surprisingly) those over 65, and those under the age of 4, are the hardest hit this year.