Credit WHO
# 6831
The latest influenza surveillance report from the World Health Organization confirms that North America continues to see the highest rate of influenza in the world, but reports signs that flu transmission is picking up in Europe, Africa, and parts of Asia.
- Globally flu samples have been predominately Influenza A (72.6%) and of those, nearly 83% were seasonal H3N2.
- Among the B viruses, Yamagata lineage viruses were leading Victoria lineage by more than 2 to 1.
Out of more than 500 viruses recently tested by Global Influenza Surveillance and Response System (GISRS), all continue to be susceptible to the antiviral drugs oseltamivir and zanamivir.
Influenza virus activity in the world
7 January 2013
Source: Laboratory confirmed data from the Global Influenza Surveillance and Response System (GISRS).
Based on FluNet reporting (as of 3 January 2013, 12:40 UTC), during weeks 50 to 51 (9 December 2012 to 22 December 2012), National Influenza Centres (NICs) and other national influenza laboratories from 77 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 36 007 specimens. 5 528 were positive for influenza viruses, of which 4 013 (72.6%) were typed as influenza A and 1 515 (27.4%) as influenza B. Of the sub-typed influenza A viruses, 431 (17.2%) were influenza A(H1N1)pdm09 and 2 078 (82.8%) were influenza A(H3N2). Of the characterized B viruses, 52 (69.3%) belong to the B-Yamagata lineage and 23 (30.7%) to the B-Victoria lineage.
Summary
During weeks 50 and 51 influenza activity continued to increase in the northern hemisphere while sporadic activity was reported from the southern hemisphere. Influenza A(H3N2) viruses remained the predominant subtype globally, followed by influenza B and A(H1N1)pdm09 viruses.
In North America, influenza activity increased and varied from localized to widespread in both Canada and the United States of America with influenza A(H3N2) as the predominant subtype. In contrast, influenza B viruses were the predominant subtype in Mexico.
In Europe, influenza activity continued to increase across the region. In recent weeks, increased activity was reported from Denmark and France. Influenza A(H1N1)pdm09, A(H3N2) and B viruses co-circulated in the region.
Increased A(H3N2) activity was reported from China and Japan while sporadic activity was reported from the region.
In the Eastern Mediterranean region, increased A(H1N1)pdm09 virus detections were reported from the West Bank and Gaza Strip where 9 deaths were recorded. Increased A(H1N1)pdm09 activity was reported from elsewhere in the region as well as A(H3N2) and influenza B viruses.
In Africa, increased detections of influenza B viruses were reported from Algeria while A(H1N1)pdm09 viruses were detected in the Democratic Republic of the Congo.
In the northern hemisphere, 426 A(H3N2), 49 A(H1N1)pdm09, and 164 B viruses have been tested for antiviral resistance to neuraminidase inhibitors and all have remained resistant to oseltamivir and zanamivir.
In Europe, the Mediterranean, and parts of Africa the A(H1N1)pdm09 virus appear to be a bit more common than is currently being reported in North America. The following is a summary from the latest EuroFlu report (week 52).
Influenza activity is increasing mainly due to influenza detections in western EuropeSummary, week 52/2012
Influenza-like illness (ILI) and acute respiratory infection (ARI) consultation rates continue to rise, following a west-to-east progression across the WHO European Region. For the second week, reporting of influenza surveillance data was incomplete, due to the holiday period.
Countries mainly in the western part of the Region reported co-circulation of influenza A(H1N1)pdm09, A(H3N2) and type B viruses. The proportion of A(H1N1)pdm09 is considerably higher in comparison with the same time period last season. The number of reported hospitalizations due to severe acute respiratory infection (SARI) remains low, with no cases being associated with influenza detection.
