Synopsis: During week 17 (April 21-27, 2013), influenza activity decreased in the United States.

o Viral Surveillance: Of 2,746 specimens tested and reported by collaborating laboratories, 177 (6.5%) were positive for influenza.

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

o Influenza-Associated Pediatric Deaths: Seven pediatric deaths were reported.

o Influenza-Associated Hospitalizations: Acumulativerate for the season of 44.2 laboratory-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 1.0%. This is below the national baseline of 2.2%. All 10 regions reported ILI below region-specific baseline levels. One state experienced low activity; 48 states and New York City experienced minimal activity, and the District of Columbia and 1 state had insufficient data.

o Geographic Spread of Influenza:Puerto Rico and 3 states reported regional influenza activity; 6 states reported local influenza activity; the District of Columbia, Guam, and 36 states reported sporadic influenza activity; 5 states reported no influenza activity, and the U.S. Virgin Islands did not report.

Stephen B. Thacker CDC Library collection

United States