Influenza virus activity in the world
13 September 2013
Based on FluNet reporting (as of 10 September 2013, 08:45 UTC), during weeks 34 to 35 (18 August 2013 to 31 August 2013), National Influenza Centres (NICs) and other national influenza laboratories from 69 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 21 167 specimens. 1546 were positive for influenza viruses, of which 1295 (83.8%) were typed as influenza A and 251 (16.2%) as influenza B. Of the sub-typed influenza A viruses, 500 (46.4%) were influenza A(H1N1)pdm09, 576 (53.5%) were influenza A(H3N2) and 1 (0.1%) was influenza A(H3N2)v. Of the characterized B viruses, 20 (87%) belong to the B-Yamagata lineage and 3 (13%) to the B-Victoria lineage.
During weeks 34 and 35, global influenza activity remained low. (H3N2) viruses were the predominant virus detected followed by A(H1N1)pdm09 and influenza B viruses.
In Oceania, influenza A(H1N1)pdm09 virus activity increased in Australia and co-circulated with A(H3N2) viruses, while influenza A(H3N2) and B activity remained high in New Zealand.
In Africa, A(H3N2) and influenza B viruses co-circulated throughout the region. Increased influenza B activity was reported from the Central African Republic while A(H3N2) remained predominant in South Africa.
Influenza virus activity was low in Asia. A(H3N2) virus was predominant in China and Thailand and co-circulated with A(H1N1)pdm09 virus in India.
In Central and South America, all three virus types were detected and co-circulated in varying proportions. A(H3N2) virus remained predominant in Cuba while A(H1N1)pdm09 was the most frequently detected virus in Ecuador.
Influenza activity remained low in the Europe and North America.
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