Influenza

Influenza update

7 April - Update number 208

Summary

Globally, the northern hemisphere influenza season appeared to be approaching interseasonal levels in most countries. The proportion of influenza B detections however increased slightly in many regions, especially Asia, the Middle East, and North America.

  • In North America, influenza levels continued to decline and the season was coming to its end. Late season circulation of influenza B continued, however, the overall levels of influenza remained low.
  • In North America, influenza levels continued to decline and the season was coming to its end. Late season circulation of influenza B continued, however, the overall levels of influenza remained low.
  • In Eastern Asia, influenza activity was approaching interseasonal levels, with influenza B emerging as the current predominant virus. This timing aligns with previous seasonal influenza trends in the region. Mongolia continues to experience elevated influenza activity, despite levels beginning to decline.
  • In Tropical Asia, influenza activity continued to decline, aligning with global seasonal trends. While in Thailand influenza activity remained elevated, small decreases were seen.
  • In Northern Africa and Western Asia, influenza activity remained low despite the increasing proportion of influenza B positive samples.
  • In the Caribbean, influenza activity remained low and at interseasonal levels in most countries, however ILI activity and influenza detections increased in Guyana and Guadeloupe.
  • In the Southern Hemisphere, influenza activity remained low and detections were sporadic.
  • Based on FluNet reporting (as of 3 April 2014, 12:35 UTC), during weeks 11 to 12 (9 March 2014 to 22 March 2014), National Influenza Centres (NICs) and other national influenza laboratories from 96 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 65 498 specimens. 10 986 were positive for influenza viruses, of which 7407 (67.4%) were typed as influenza A and 3579 (32.6%) as influenza B. Of the sub-typed influenza A viruses, 2747 (57%) were influenza A(H1N1)pdm09 and 2072 (43%) were influenza A(H3N2). Of the characterized B viruses, 222 (87.1%) belong to the B-Yamagata lineage and 33 (12.9%) to the B-Victoria lineage.

Full influenza update


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For updates on the influenza at the human-animal interface see the following WHO web pages:


Source of data

The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.
The updates are based on available epidemiological and virological data sources, including FluNet (reported by the WHO Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.

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