Global & Disaster Medicine

2017-2018 Influenza Season Week 14 ending April 7, 2018



During week 14 (April 1-7, 2018), influenza activity decreased in the United States.

  • Viral Surveillance: Overall, influenza A(H3) viruses have predominated this season. Since early March, influenza B viruses have been more frequently reported than influenza A viruses. The percentage of respiratory specimens testing positive for influenza in clinical laboratories decreased.
  • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
  • Influenza-associated Pediatric Deaths: Nine influenza-associated pediatric deaths were reported.
  • Influenza-associated Hospitalizations: A cumulative rate of 101.6 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
  • Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.1%, which is below the national baseline of 2.2%. Six of 10 regions reported ILI at or above region-specific baseline levels. Two states experienced high ILI activity; two states experienced moderate ILI activity; 11 states experienced low ILI activity; and New York City, the District of Columbia, Puerto Rico, and 35 states experienced minimal ILI activity.
  • Geographic Spread of Influenza: The geographic spread of influenza in seven states was reported as widespread; Guam, Puerto Rico and 22 states reported regional activity; the District of Columbia and 16 states reported local activity; and the U.S. Virgin Islands and five states reported sporadic activity.

INFLUENZA Virus Isolated

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national levels of ILI and ARI



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