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Influenza Update N? 206, 10 March 2014 (WHO, edited)

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  • Influenza Update N? 206, 10 March 2014 (WHO, edited)

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

    Influenza Update N? 206, 10 March 2014

    • In North America, influenza activity continued to decrease overall, but remained elevated in some regions. Influenza A(H1N1)pdm09 continued as the predominant circulating virus, and influenza B detections increased slightly throughout the region.
    • In Europe, influenza activity was variable between countries. Overall trends showed slight increases in activity in the northern and eastern regions, and decreases in the southwestern region. Influenza A(H1N1)pdm09 and A(H3N2) continued to circulate with variable predominance among countries.
    • In Eastern Asia, influenza A(H1N1)pdm09 remained predominant and trends were inconsistent. Influenza activity in China began to decrease while activity in Mongolia continued to increase.
    • In Tropical Asia, influenza activity was largely decreased, however Thailand reported increasing influenza A(H1N1)pdm09 activity.
    • In Northern Africa and Western Asia, influenza activity varied, with Egypt continuing to report high activity of influenza A(H1N1)pdm09.

    Based on FluNet reporting (as of 4 March 2014, 12:15 UTC), during weeks 7 to 8 (9 February 2014 to 22 February 2014), National Influenza Centres (NICs) and other national influenza laboratories from 80 countries, areas or territories reported data.

    The WHO GISRS laboratories tested more than 80 809 specimens.

    16 409 were positive for influenza viruses, of which 13 869 (84.5%) were typed as influenza A and 2540 (15.5%) as influenza B.

    Of the sub-typed influenza A viruses, 6283 (70.6%) were influenza A(H1N1)pdm09 and 2612 (29.4%) were influenza A(H3N2).

    Of the characterized B viruses, 124 (84.9%) belonged to the B-Yamagata lineage and 22 (15.1%) to the B-Victoria lineage.

    For updates on human infections with avian influenza A(H7N9) virus see the WHO web site


    Countries in the temperate zone of the northern hemisphere

    North America

    In North America, influenza activity continued to follow an overall decreasing trend. Influenza A(H1N1)pdm09 remained the predominant virus detected in the region, with a slight increase in influenza B activity.

    Canada experienced a decrease in influenza activity, similar to previous weeks. The age group most affected by influenza this season continued to be adults age ranging from 20‐64. Influenza A(H1N1)pdm09 remained the predominant virus subtype with increased detections of influenza B.

    In the United States of America (USA) in the third week of February, influenza activity continued a downward trend from the previous weeks. The proportion of outpatient visits for influenza‐like illness (ILI) decreased from 3.0% to 2.3%, however, this was still slightly above the national baseline of 2.0%. The percentage of deaths due to Pneumonia & Influenza was 7.6%, which is above the the epidemic threshold of 7.4%. Influenza A(H1N1)pdm09 continued to be the predominant virus affecting the USA.

    In Mexico, influenza detections decreased, but activity remained elevated overall. The proportion of ILI/SARI‐associated medical visits decreased from 3.8% to 2.8% during the past two weeks. The pneumonia rate decreased for the third consecutive week, but Acute Respiratory Infection (ARI) activity increased slightly from the previous week. Of the documented influenza‐associated deaths, 90% of them have been related to influenza A(H1N1)pdm09.



    In the European region, influenza activity was variable. Influenza activity trends showed slightly increasing or continually elevated activity in eastern and northern Europe, and decreasing activity in southwest Europe.

    Finland and Greece reported high activity, and the remaining countries reported medium or low activity. Overall, the current European influenza season appeared to be less intense than the 2012‐2013 season. Influenza A(H1N1)pdm09 and A(H3N2) viruses circulated throughout the region with variability in predominance or codominance among different countries.
    A(H1N1)pdm09 virus was detected slightly more frequently overall.


    Northern Africa and the Western and Central Asia region

    In Central and Western Asia, influenza activity was variable. The number of specimens positive for influenza continued to decrease in the Islamic Republic of Iran and Turkey.

    A(H1N1)pdm09 activity remained high in Egypt with an elevated proportion of outpatient ILI visits. Influenza activity remained low in the remainder of the region.

    Eastern Asia

    In the Eastern Asian region A(H1N1)pdm09, A(H3N2), and influenza B viruses co‐circulated, however A(H1N1)pdm09 virus remained the predominant subtype.

    In China, influenza activity decreased in the north and south. Hong Kong Special Administrative Region of China, however, reported a continued high level of influenza activity.

    Mongolia continued to experience high A(H1N1)pdm09 influenza activity, and also reported increased ILI and pneumonia cases. Influenza activity remained elevated in the Republic of Korea, with similar proportions of A(H1N1)pdm09, A(H3N2), and influenza B viruses detected. In Japan, ILI activity declined.

    Countries in the tropical zone

    Tropical countries of the Americas/Central America and the Caribbean

    Overall influenza activity in the Caribbean, Central America and tropical areas of South America was at low levels.

    Central African tropical region

    In Africa, in general influenza activity was low, however Madagascar reported increased detections of A(H3N2) virus and Ghana continued to report influenza B activity.

    Tropical Asia

    Influenza activity among South‐East Asian countries was low in general. Thailand reported an increase in ILI cases and A(H1N1)pdm09 activity.

    Countries in the temperate zone of the southern hemisphere

    In the Southern Hemisphere, ILI activity remained low, with sporadic detections of A(H1N1)pdm09, A(H3N2)and influenza B viruses.


    Source of data

    The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.

    The updates are based on available epidemiological and virological data sources, including FluNet (reported by the WHO Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.

    Link to web pages