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24 May 2013

Influenza virus activity in the world (WHO, May 24 2013, edited)

[Source: World Health Organization, full page: (LINK). Edited.]

Influenza virus activity in the world

24 May 2013

Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).

Based on FluNet reporting (as of 21 May 2013, 10:30 UTC), during weeks 18 to 19 (28 April 2013 to 11 May 2013), National Influenza Centres (NICs) and other national influenza laboratories from 76 countries, areas or territories reported data.

The WHO GISRS laboratories tested more than 22 766 specimens.

1 820 were positive for influenza viruses, of which 1 099 (60.4%) were typed as influenza A and 721 (39.6%) as influenza B.

Of the sub-typed influenza A viruses, 699 (78.5%) were influenza A(H1N1)pdm09 and 191 (21.4%) were influenza A(H3N2).

Of the characterized B viruses, 16 (59.3%) belong to the B-Yamagata lineage and 11 (40.7%) to the B-Victoria lineage.



During weeks 18 and 19, influenza activity remained low in general. Globally, A(H1N1)pdm09 viruses were the predominant circulating subtype at low levels, followed by influenza B and A(H3N2).

In Asia, A(H1N1)pdm09 viruses were the predominant subtype and co-circulated with A(H3N2) and influenza B viruses.

In the African region, Madagascar experienced increased activity due to A(H1N1)pdm09 virus. Sporadic A(H1N1)pdm09, A(H3N2) and influenza B activity was reported in rest of the continent.

In Central and South America, influenza activity was low, however increased detections of A(H1N1)pdm09 viruses were observed.

In the Eastern Mediterranean region, sporadic detections of A(H1N1)pdm09 and influenza B viruses were reported.

Overall influenza activity remained low in Europe, North America and Oceania with reports of sporadic detections of all three subtypes.

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