Influenza virus activity in the world

26 August 2011

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

Virological summary

During weeks 31 to 32 (31 July 2011 to 13 August 2011), a number of countries in the southern hemisphere reported laboratory confirmed influenza virus activity at variable levels ranging from regional to sporadic. Influenza detection in the northern hemisphere remained sporadic.

In Australia, increased influenza activity due to both A(H1N1)2009 and influenza B virus was reported. The predominant virus in New Zealand was influenza B with lower levels of influenza A(H3N2) and A(H1N1)2009 co-circulating. In southern Asia, regional outbreaks of A(H1N1)2009 occurred in Cambodia.

In South America, the predominant circulating virus in Chile was A(H1N1)2009 with co-circulation of A(H3N2). Some other countries in central and South America also reported detection of influenza viruses.

In Africa, sporadic detections of influenza A(H1N1)2009, A(H3N2) and B were reported from some countries. In general, influenza virus activity was low.

The vast majority of viruses characterized recently in the WHO Global Influenza Surveillance and Response System (GISRS) remain antigenically similar to the WHO recommended vaccines for the 2010-2011 northern hemisphere and 2011 southern hemisphere influenza seasons.

During weeks 31 to 32 (31 July 2011 to 13 August 2011), National Influenza Centres (NICs) from 70 countries, areas or territories reported data to FluNet*. A total of 923 specimens were reported as positive for influenza viruses, 660 (71.5%) were typed as influenza A and 263 (28.5%) as influenza B. Of the sub-typed influenza A viruses reported, 51.8% were influenza A(H1N1)2009 and 48.2% were influenza A(H3N2).

(FluNet data as of 23 August 2011 15:00 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)2009: Argentina, Australia, Bolivia (Plurinational State of), Cambodia, Cameroon, Chile, China, Colombia, Dominican Republic, France - New Caledonia, Germany, Ghana, Honduras, India, Kenya, Madagascar, New Zealand, Panama, Slovakia, South Africa, United Republic of Tanzania, United States of America, Uruguay, Viet Nam
  • Influenza A(H1N1) old seasonal virus: no report
  • Influenza A(H3N2): Argentina, Australia, Bolivia (Plurinational State of), Brazil, Burkina Faso, Canada, Chile, China, Colombia, Cuba, Ghana, Honduras, India, Kenya, Lao People's Democratic Republic, Madagascar, Mexico, New Zealand, Norway, Paraguay, Peru, Senegal, United Kingdom of Great Britain and Northern Ireland, United Republic of Tanzania, United States of America, Uruguay
  • Influenza A(H5): no report
  • Influenza B: Australia, Brazil, Burkina Faso, Cambodia, Cameroon, Chile, China, Ghana, Honduras, India, Japan, Kenya, Madagascar, Mauritius, New Zealand, Slovakia, South Africa, Spain, Sri Lanka, Sweden, United Kingdom of Great Britain and Northern Ireland, United States of America, Viet Nam, Zambia
  • No influenza detected: Algeria, Angola, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Central African Republic, Costa Rica, Denmark, Ecuador, El Salvador, Estonia, Ethiopia, Finland, France, Georgia, Iceland, Indonesia, Iran (Islamic Republic of), Ireland, Jamaica, Latvia, Lithuania, Mali, Netherlands, Pakistan, Poland, Republic of Korea, Romania, Russian Federation, Slovenia