Influenza virus activity in the world
7 June 2013
Based on FluNet reporting (as of 4 June 2013, 11:25 UTC), during weeks 20 to 21 (12 May 2013 to 25 May 2013), National Influenza Centres (NICs) and other national influenza laboratories from 87 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 30 922 specimens. 1 894 were positive for influenza viruses, of which 1 208 (63.8%) were typed as influenza A and 686 (36.2%) as influenza B. Of the sub-typed influenza A viruses, 766 (73.9%) were influenza A(H1N1)pdm09 and 271 (26.1%) were influenza A(H3N2). Of the characterized B viruses, 14 (63.6%) belong to the B-Yamagata lineage and 8 (36.4%) to the B-Victoria lineage.
During weeks 20 and 21, influenza activity remained low in the northern and southern hemispheres. A(H1N1)pdm09 viruses were the predominant subtype circulating globally, followed by influenza B and A(H3N2) viruses.
In Oceania, sporadic influenza activity was detected with New Zealand reporting an increase in the number of influenza B virus detections.
In Central and South America increased A(H1N1)pdm09 activity was reported from a number of countries. Influenza activity remained low throughout the rest of the region.
In Africa, A(H1N1)pdm09 and influenza B viruses co-circulated throughout the region with increased A(H1N1)pdm09 and influenza B activity reported by South Africa and Rwanda respectively.
In Asia there was a further decline in influenza activity. A(H1N1)pdm09 remained the predominant circulating subtype followed A(H3N2).
Influenza activity in Europe and North America remained low.
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