Influenza activity of 15th week (Apr.11-Apr.17)2010 in U.S.A.

Situation Update
Flu Activity: On the one-year anniversary of the 2009 H1N1 pandemic, CDC reports that flu activity is low nationwide, although 2009 H1N1 viruses continue to be reported in small numbers. According to the April 11-17 FluView, flu activity in the United States is declining across most key indicators. The most recent CDC mid-level estimates are that about 60 million people in the United States have been infected with 2009 H1N1, 270,000 have been hospitalized and 12,270 people have died from 2009 H1N1-related illness. Sporadic flu activity, caused by either 2009 H1N1 or seasonal flu viruses, is expected to continue throughout the summer in the United States. Internationally, 2009 H1N1 flu is still circulating, including in the Southern Hemisphere, which is entering its flu season. For more information, please see the international situation update. For more information about the first year of the 2009 H1N1 pandemic, see “The Year in Review.”
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2009-2010 Influenza Season Week 15 ending April 17, 2010
All data are preliminary and may change as more reports are received.

Synopsis:
During week 15 (April 11-17, 2010), influenza activity decreased in the U.S.

37 (2.1%) 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 were positive for influenza.
All 20 subtyped influenza A viruses were 2009 influenza A (H1N1).
The proportion of deaths attributed to pneumonia and influenza (P&I) was at the epidemic threshold.
No influenza-associated pediatric deaths were reported.
The proportion of outpatient visits for influenza-like illness (ILI) was 1.1%, which is below the national baseline of 2.3%. All 10 regions reported ILI below region-specific baseline levels.
No states reported widespread or regional influenza activity. Four states reported local influenza activity. The District of Columbia, Guam, Puerto Rico, and 31 states reported sporadic influenza activity. Fourteen states reported no influenza activity, and the U.S. Virgin Islands and one state did not report.

Pneumonia and Influenza Hospitalization and Death Tracking:
The Aggregate Hospitalization and Death Reporting Activity (AHDRA) system was implemented on August 30, 2009, and replaces the weekly report of laboratory confirmed 2009 H1N1-related hospitalizations and deaths that began in April 2009. Jurisdictions report to CDC the number of hospitalizations and deaths resulting from all types or subtypes of influenza, not just those associated with 2009 H1N1. Counts were reset to zero on August 30, 2009. From August 30, 2009 – April 3, 2010, 41,883 laboratory-confirmed influenza-associated hospitalizations and 2,125 laboratory-confirmed influenza-associated deaths were reported to CDC.

Reporting of influenza-associated hospitalizations and deaths through AHDRA was discontinued during the week ending April 3, 2010 (week 13). CDC will continue to use its traditional influenza surveillance systems to track the remainder of the 2009-10 season

Pneumonia and Influenza (P&I) Mortality Surveillance
During week 15, 7.6% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was at the epidemic threshold of 7.6% for week 15.The number of deaths by pneumonia and influenza is 828 people died during 15 th week (Apr.11-Apr-17) 2010.

Influenza-Associated Pediatric Mortality
No influenza-associated pediatric deaths were reported to CDC during week 15.

Since August 30, 2009, CDC has received 272 reports of influenza-associated pediatric deaths that occurred during the current influenza season (48 deaths in children less than 2 years old, 30 deaths in children 2-4 years old, 102 deaths in children 5-11 years old, and 92 deaths in children 12-17 years old). Two hundred twenty-one (81%) of the 272 deaths were due to 2009 influenza A (H1N1) virus infections, 50 were associated with an influenza A virus for which the subtype is undetermined, and one was associated with an influenza B virus infection. A total of 281 deaths in children associated with 2009 influenza A (H1N1) virus infection have been reported to CDC.

Among the 272 deaths in children, 145 children had specimens collected for bacterial culture from normally sterile sites and 50 (34.5%) of the 145 were positive; Streptococcus pneumoniae was identified in 11 (22.0%) of the 50 children, and Staphylococcus aureus was identified in 15 (30.0%) of the 50 children. Four S. aureus isolates were sensitive to methicillin, ten were methicillin resistant, and one did not have sensitivity testing performed. Thirty-three (66.0%) of the 50 children with bacterial coinfections were five years of age or older, and 17 (34.0%) of the 50 children were 12 years of age or older.

Influenza-Associated Hospitalizations
Laboratory-confirmed influenza-associated hospitalizations are monitored using a population-based surveillance network that includes the 10 Emerging Infections Program (EIP) sites (CA, CO, CT, GA, MD, MN, NM, NY, OR and TN) and six new sites (IA, ID, MI, ND, OK and SD).

During September 1, 2009 – April 17, 2010, the following preliminary laboratory-confirmed overall influenza associated hospitalization rates were reported by EIP and the new sites (rates include influenza A, influenza B, and 2009 influenza A (H1N1)):

Rates [EIP (new sites)] for children aged 0-4 years and 5-17 years were 6.7 (10.7) and 2.5 (3.6) per 10,000, respectively. Rates [EIP (new sites)] for adults aged 18-49 years, 50-64 years, and ≥ 65 years were 2.4 (1.7), 3.2 (2.0) and 2.8 (1.8) per 10,000, respectively.

http://www.cdc.gov/flu/weekly/