[Source: World Health Organization, full page: (LINK). Edited.]
Influenza virus activity in the world
15 March 2013
Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).
Based on FluNet reporting (as of 12 March 2013, 10:45 UTC), during weeks 8 to 9 (17 February 2013 to 2 March 2013), National Influenza Centres (NICs) and other national influenza laboratories from 101 countries, areas or territories reported data.
The WHO GISRS laboratories tested more than 79 430 specimens. 20 386 were positive for influenza viruses, of which 12 859 (63.1%) were typed as influenza A and 7 527 (36.9%) as influenza B.
Of the sub-typed influenza A viruses, 5 355 (62.1%) were influenza A(H1N1)pdm09 and 3 264 (37.9%) were influenza A(H3N2).
Of the characterized B viruses, 432 (89.8%) belonged to the B-Yamagata lineage and 49 (10.2%) to the B-Victoria lineage.
During weeks 8 and 9, influenza activity declined in the northern hemisphere and remained low in the southern hemisphere. Influenza A(H1N1)pdm09 viruses remained the predominant virus circulating globally, followed by A(H3N2) and influenza B viruses.
In the European region, influenza activity continued to decline.
While influenza A(H1N1)pdm09 and B viruses co-circulated in many parts of Europe, A(H1N1)pdm09 viruses were predominant in eastern and south western Europe.
Five A(H1N1)pdm09 viruses with reduced susceptibility to oseltamivir were detected in the Netherlands, Switzerland and United Kingdom.
Of the five, three cases reported history of oseltamivir treatment.
One influenza B virus with reduced susceptibility to oseltamivir was detected from a case in the United Kingdom with no exposure to antiviral treatment.
In North America, influenza activity decreased in general with B viruses becoming predominant.
In Asia, in southern China influenza activity associated with A(H1N1)pdm09 viruses continued to increase, while it decreased in the northern parts. A(H3N2) activity was reported from a number of other countries in the region at varying levels.
Sporadic detections of influenza viruses continued to be reported from the African region. Influenza B was the predominant virus detected, followed by A(H1N1)pdm09 and A(H3N2) viruses.
Influenza activity remained low in Central and South America with A(H3N2) and influenza B viruses detected at low levels.