Influenza virus activity in the world
6 June 2011
Virological summary
During weeks 19 to 20 (8 May 2011 to 21 May 2011), in general influenza activity remained at low levels in both northern and southern hemisphere countries except South Africa, where widespread A(H1N1)2009 activity was reported.
Of the low numbers of influenza viruses detected, the type and subtype of predominating circulating viruses varied in different countries. Influenza A(H1N1)2009 was predominant in some countries in Africa e.g. South Africa and in Central America e.g. Costa Rica and the Dominican Republic, while A(H3N2) was the most prevalent virus in a few other countries such as Bolivia, Cuba and Rwanda. In Canada, China, Japan and Madagascar, influenza B was the predominant virus circulating at low levels.
The vast majority of recently characterized viruses remain antigenically similar to the WHO recommended vaccine viruses for the 2010-2011 northern hemisphere and 2011 southern hemisphere influenza seasons.
During weeks 19 to 20 (8 May 2011 to 21 May 2011), National Influenza Centres (NICs) from 74 countries, areas or territories reported data to FluNet. A total of 721 specimens were reported as positive for influenza viruses, 261 (36.2%) were typed as influenza A and 460 (63.8%) as influenza B. Of the sub-typed influenza A viruses reported, 66% were influenza A(H1N1)2009 and 34% were influenza A(H3N2).
(FluNet data as of 31 May 2011 14:45 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)2009: Australia, Cambodia, Canada, Chile, China, Dominican Republic, Estonia, Ghana, India, Iran (Islamic Republic of), Kenya, Lao People's Democratic Republic, Madagascar, Russian Federation, South Africa, Sri Lanka, Sweden, Thailand, United States of America, Viet Nam
- Influenza A(H1N1) (old seasonal virus): no report
- Influenza A(H3N2): Australia, Canada, Chile, China, Cuba, Ghana, India, Iran (Islamic Republic of), Japan, Madagascar, Rwanda, South Africa, Sweden, United Republic of Tanzania, United States of America
- Influenza A(H5): no report
- Influenza B: Austria, Brazil, Cambodia, Cameroon, Canada, China, Estonia, Ghana, Honduras, Iran (Islamic Republic of), Japan, Kenya, Latvia, Madagascar, Russian Federation, South Africa, Sri Lanka, Sweden, Thailand, Turkey, United States of America, Viet Nam
- No influenza activity: Algeria, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Central African Republic, Costa Rica, Croatia, Denmark, Ecuador, El Salvador, Ethiopia, Finland, France, Georgia, Germany, Hungary, Iceland, Indonesia, Kyrgyzstan, Lithuania, Mauritius, Mexico, Morocco, Netherlands, Nigeria, Norway, Panama, Paraguay, Portugal, Romania, Senegal, Serbia, Slovakia, Slovenia, Spain, Tunisia, Uganda, Ukraine
