Influenza

Influenza virus activity in the world

16 December 2011

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

Virological summary

During weeks 47 to 48 (20 November 2011 to 3 December 2011), the number of laboratory confirmed influenza virus detections in general remained sporadic in most parts of the world except in a few countries. The predominant virus subtype detected was influenza A(H3N2).

In the northern hemisphere influenza activity remained low with the exception of a few countries. Regional outbreaks of influenza A(H1N1)pdm09 and B viruses continued to persist in Cambodia. Influenza A(H1N1)pdm09, A(H3N2) and B viruses were detected at low levels elsewhere in Asia, Europe and Northern America.

In Central America, influenza activity was low in general. In Costa Rica, increased detections of A(H3N2) viruses were reported with co-circulation of A(H1N1)pdm09.

In the southern hemisphere, an increase in the number of A(H1N1)pdm09 and B viruses was reported by Brazil. Elsewhere sporadic detections of influenza A(H1N1)pdm09, A(H3N2) and B viruses were reported in Africa, Oceania and South America.

Two additional variant influenza A virus infections were detected in children in the United States of America. One case from West Virginia was infected with the influenza A(H3N2) variant virus with genes from swine, human, and avian lineages. The M gene was from the A(H1N1)pdm09 virus. This is the eleventh human infection with this variant A(H3N2) virus. The other case from Minnesota was infected with an influenza A(H1N2) virus that circulates in swine in the United States. This is the second case of human infection with this influenza A(H1N2) virus initially reported to CDC, Atlanta, in 2007.

FluNet summary

During weeks 47 to 48 (20 November 2011 to 3 December 2011), National Influenza Centres (NICs) from 83 countries, areas or territories reported data to FluNet. A total of 1068 specimens were reported as positive for influenza viruses, 684 (64%) were typed as influenza A and 384 (36%) as influenza B. Of the sub-typed influenza A viruses reported, 11.2% were influenza A(H1N1)pdm09 and 88.3% were influenza A(H3N2).

FluNet data as of 13 December 2011 09:45 UTC. Some NICs report to FluNet retrospectively leading to updates of previous summary data.

Influenza virus detection by type/subtype in countries, areas or territories

  • Influenza A(H1N1)pdm09: Australia, Bolivia (Plurinational State of), Brazil, Cambodia, Cameroon, Canada, China, Costa Rica, Czech Republic, Ecuador, Italy, Kenya, Madagascar, Mexico, Panama, Spain, Sweden, United States of America, Viet Nam
  • Influenza A(H1N1) old seasonal virus: Iran (Islamic Republic of) This is being sent to a WHO CC for confirmation.
  • Influenza A(H3N2): Australia, Belgium, Bolivia (Plurinational State of), Brazil, Cambodia, Cameroon, Canada, Chile, China, Costa Rica, Denmark, El Salvador, Germany, Ghana, India, Iran (Islamic Republic of), Ireland, Israel, Italy, Japan, Jordan, Kenya, Lao People's Democratic Republic, Mexico, Morocco, Netherlands, Nigeria, Norway, Republic of Korea, Romania, South Africa, Spain, Sri Lanka, Sweden, Thailand, Tunisia, Turkey, United Kingdom of Great Britain and Northern Ireland, United States of America, Viet Nam
  • Influenza B: Australia, Bolivia (Plurinational State of), Brazil, Cambodia, Cameroon, Canada, China, France, Germany, Ghana, Honduras, India, Iran (Islamic Republic of), Ireland, Israel, Japan, Kenya, Lao People's Democratic Republic, Latvia, Nepal, Netherlands, Nigeria, Norway, Qatar, Republic of Korea, Senegal, South Africa, Sri Lanka, Sweden, Switzerland, Thailand, United Kingdom of Great Britain and Northern Ireland, United States of America, Viet Nam
  • No influenza detected: Albania, Angola, Armenia, Austria, Azerbaijan, Belarus, Bosnia and Herzegovina, Bulgaria, Croatia, Dominican Republic, Estonia, Finland, France - French Guiana, France - Guadeloupe, France - Martinique, Georgia, Greece, Hungary, Iceland, Kyrgyzstan, Lithuania, Luxembourg, Poland, Portugal, Republic of Moldova, Russian Federation, Serbia, Slovakia, Slovenia, Uganda, Ukraine, Zambia
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Snapshot global influenza virus circulation (GISRS-FluNet, 13 December 2011)