27 April 2012- Update number 158
Table of content
•Seasonal influenza activity has peaked in most countries in the temperate regions of the northern hemisphere.
•In North America, in general influenza transmission is low and decreasing for four consecutive weeks in the United States of America (USA) and for three weeks in Canada. Influenza A(H3N2) viruses have predominated during the current season nationally and in most regions of USA, whereas influenza B viruses continue to be the predominant in Canada. A(H1N1)pdm09 continued to co-circulate in Canada, USA and Mexico.
•In almost all European countries, their influenza season have peaked for several weeks now showing a continuously decreasing incidence of ILI /ARI, and a reduction in the number of SARI cases. Influenza A(H3N2) viruses have been predominant this season with increasing proportion of influenza B virus detection.
•Influenza activity in the temperate countries of Asia has shown an overall decrease. The proportion of influenza A(H3N2) virus detection has increased over influenza B in both northern China and Mongolia, but for Japan, influenza A(H3N2) viruses have been the predominant subtype throughout the season. In the Republic of Korea, influenza B viruses are still predominant over influenza A viruses.
•Influenza A(H1N1)pdm09 viruses were screened for susceptibility to neuraminidase inhibitors in nine countries in western Europe, and all tested were susceptible. However, in the USA, a slight increase to 2% in levels of resistance to oseltamivir has been noticed for influenza A(H1N1)pdm09 isolates.
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.