Synopsis: During week 15 (April 7-13, 2013), influenza activity decreased in the United States.

o Viral Surveillance : Of 3,802 specimens tested and reported by collaborating laboratories, 354 (9.3%) were positive for influenza.

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

o Influenza-Associated Pediatric Deaths: Tenpediatric death swerereported.

o Influenza-Associated Hospitalizations: Acumulative rate for theseason of 43.7laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. Of reported hospitalizations, 50% were among adults 65 years and older.

o Outpatient Illness Surveillance : The proportion of outpatient visits for influenza-like illness (ILI) was 1.3%. This is below the national baseline of 2.2%. One of 10 regions reported ILI at or above region-specific baseline levels. One state experienced mode rate activity; one state experienced low activity; 48 states and New York City experienced minimal activity, and the District of Columbia had insufficient data.

o Geographic Spread of Influenza : Three states reported widespread influenza activity; 6 states reported regional influenza activity; Puerto Rico and 8 states reported local influenza activity; the District of Columbia and 33 states reported sporadic influenza activity; Guam reported no influenza activity, and the U.S. Virgin Islands did not report.

Stephen B. Thacker CDC Library collection

United States