Influenza virus activity in the world
9 December 2013
Based on FluNet reporting (as of 3 December 2013, 11:20 UTC), during weeks 46 to 47 (10 November 2013 to 23 November 2013), National Influenza Centres (NICs) and other national influenza laboratories from 92 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 31 592 specimens. 1169 were positive for influenza viruses, of which 852 (72.9%) were typed as influenza A and 317 (27.1%) as influenza B. Of the sub-typed influenza A viruses, 331 (51.8%) were influenza A(H1N1)pdm09, 308 (48.2%) were influenza A(H3N2). Of the characterized B viruses, 13 (92.9%) belong to the B-Yamagata lineage and 1 (7.1%) to the B-Victoria lineage.
During weeks 46 and 47, influenza activity increased slightly in the northern hemisphere and remained low in the southern hemisphere. A(H1N1)pdm09 viruses were the predominant subtype globally, followed by A(H3N2) and influenza B viruses.
In the European region, sporadic influenza activity was detected in some countries, however in general influenza activity remained low. All three subtypes were detected.
Influenza activity continued to increase slightly in North America. A(H1N1)pdm09 was the predominant subtype detected in Canada and the United States of America.
In Asia, overall activity remained low with A(H3N2) activity predominant in Thailand and all three virus subtypes detected in China.
In Africa, influenza activity was low, although increased detections of A(H3N2) viruses were reported in Côte d’Ivoire and Ethiopia, and influenza B viruses circulated in Senegal.
In the Caribbean, Central and South America, influenza activity remained low. Influenza B viruses were detected in some countries in the Caribbean while A(H1N1)pdm09 viruses were predominant in South American region.
Influenza activity remained low in Oceania.