31 August 2012 - Update number 167
• Most countries in the northern temperate zone have stopped weekly reporting or moved over to out of season surveillance schedules. The United States of America has discovered new cases of swine origin influenza A(H3N2)v in humans; no sustained human-to-human transmission has been identified so far.
• In the tropical zone, the countries reporting notable influenza activity are Brazil, Costa Rica, Cuba, Ecuador, El Salvador, Honduras, Nicaragua Panama, Peru, and the Plurinational State of Bolivia in the Americas (influenza A(H1N1)pdm09, A(H3N2) and type B); Ghana and Madagascar in sub-Saharan Africa (influenza A(H3N2) and type B); Bhutan, Cambodia, southern China, China Hong Kong Special Administrative Region, India, Lao People's Democratic Republic, Singapore, Sri Lanka and Viet Nam in Asia (influenza A(H3N2) and type B).
• Influenza activity decreased in temperate countries of the southern hemisphere. Australia, Chile, New Zealand, Paraguay and South Africa, continue to report declines in most transmission indicators. Argentina continues to report very low numbers of detections compared to previous seasons.
• Influenza A(H3N2) viruses are the most commonly reported type/sub-type in recent weeks in most countries of the southern hemisphere temperate region including Chile, South Africa, and Australia. However, in Central America the previously reported transmission of influenza A(H1N1)pdm09 has now largely transition to a predominance of influenza type B. In tropical Asia, southern China and Southeast Asia have been reporting mostly A(H3N2), whereas Bhutan, India and Sri Lanka have had both influenza A(H1N1) and type B circulating.
• Reports of neuraminidase resistance continue to be very uncommon. Notably, Australia reports that a large proportion of the influenza A(H3N2) viruses tested so far this season demonstrated reduced titers in haemaglutination inhibition assays using ferret antisera against the vaccine viruses contained in the current southern hemisphere vaccines.
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 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.