Influenza

Influenza update - 287

17 April 2017, - Update number 287, based on data up to 02 April, 2017

Summary

Influenza activity in the temperate zone of the northern hemisphere continued to decrease. Influenza activity remained low in the temperate zone of the southern hemisphere. Worldwide, influenza A(H3N2) and B viruses were predominant, with an increased proportion of influenza B viruses detected in recent weeks.

  • In North America, influenza activity decreased slightly in Canada and the United States of America; influenza A(H3N2) viruses predominated with slight increases in influenza B virus detections. In Mexico, influenza activity decreased with all seasonal influenza subtypes detected.
  • In Europe, influenza activity continued to decrease to low levels, with detections of predominantly influenza B viruses in Northern and Eastern Europe. Influenza-like illness (ILI) and severe acute respiratory infection (SARI) indicators were generally low or below baseline.
  • In Central Asia, ILI and SARI activities decreased but an update on influenza virus detections was not available.
  • In East Asia, influenza activity continued to be reported with all seasonal influenza subtypes detected.
  • In Western Asia, influenza activity continued to decrease with influenza B viruses predominant.
  • In Southern Asia, influenza activity continued to be reported although it appeared to be decreasing. In Bhutan, ILI levels and influenza activity increased in recent weeks, with influenza A(H3N2) and B viruses circulating.
  • In South East Asia, influenza activity remained low.
  • In Northern Africa, low influenza activity was reported in Tunisia, with influenza A(H3N2) and B viruses predominant.
  • In East and West Africa, low influenza activity was reported in recent weeks, with influenza A(H1N1)pdm09, A(H3N2) and B viruses co-circulating.
  • In the Caribbean and Central America countries, respiratory virus activity remained low.
  • In tropical South America, influenza and other respiratory virus activities remained low. Respiratory syncytial virus (RSV) activity remained elevated in Colombia.
  • In the temperate zone of the Southern Hemisphere, influenza activity was at inter-seasonal levels. In Chile, ILI activity increased to seasonal threshold in recent weeks, consistent with past seasonal trends.
  • National Influenza Centres (NICs) and other national influenza laboratories from 103 countries, areas or territories reported data to FluNet for the time period from 20 March 2017 to 02 April 2017 (data as of 2017-04-14 05:41:03 UTC).The WHO GISRS laboratories tested more than 118962 specimens during that time period. 19667 were positive for influenza viruses, of which 9791 (49.8%) were typed as influenza A and 9876 (50.2%) as influenza B. Of the sub-typed influenza A viruses, 924 (26.2%) were influenza A(H1N1)pdm09 and 2609 (73.8%) were influenza A(H3N2). Of the characterized B viruses, 784 (65%) belonged to the B-Yamagata lineage and 423 (35%) to the B-Victoria lineage.

Detailed influenza update

Seasonal update




Source of data