Seasonal Flu: International Situation Update

This report provides an update to the international flu situation using data reported by the World Health Organization (WHO) on September 3.

Global Flu Activity Update
This report was created from a variety of sources, including regional WHO reports, Country reports, and CDC field staff updates. Updates are listed below under the appropriate region.

Northern Temperate

United States
The numbers of laboratory positive influenza samples increased from week 33 to week 34, but remain at a very low level. In week 34, all influenza-positive samples were influenza A, with a mixture of A(H3) and 2009 H1N1 (based on U.S. WHO/National Respiratory and Enteric Virus Surveillance System (NREVSS) data).

China
In southern China, numbers of specimens testing positive for influenza decreased in week 33, and influenza A accounted for 82.9% of positive samples (67% H3N2, 25% 2009 H1N1). In northern China, positive influenza results have been low for several weeks, and influenza A accounted for 97.1% of positive samples (85% H3N2, 9% 2009 H1N1) (based on data provided by the Chinese National Influenza Center).
Southern Temperate

South America
In Argentina, positive respiratory specimens for influenza have decreased since week 24, and influenza B is the predominant influenza virus.
In Chile, positive respiratory specimens for influenza increased in week 33, and flu-positives are a mix of influenza A and B (20% of influenza-positive samples are H3N2, 12% are 2009 H1N1, and 18% are influenza B, based on WHO Pacific American Health Organization (PAHO) data).

Africa
In South Africa, among samples tested through severe acute respiratory illness (SARI) surveillance, influenza positive samples increased from week 33 to 34, and the majority of positive samples are influenza B (based on South Africa National Institute for Communicable Diseases (NICD) data).

Tropical

Thailand
At Queen Sirikit Children’s hospital in Bangkok, rates of confirmed influenza among children 15 years and younger increased each week in August. Cases were predominantly influenza A (no subtype information) based on data collected through the International Emerging Infections Program (IEIP) and Global Disease Detection (GDD) Thailand).

Vietnam
Twice the proportion of influenza like illness (ILI) samples tested in-country in August were positive for influenza compared to July (87% of influenza-positive samples are A(H3), 12% are B, 1% 2009 H1N1, based on data reported by CDC field staff).

Selected Highlights
• On August 10, 2010, the WHO Director-General, Dr. Margaret Chan, declared an end to the 2009 H1N1 influenza pandemic, but noted that 2009 H1N1 virus will likely continue to circulate for years to come, taking on the behavior of a seasonal influenza virus.
• On February 18, 2010, WHO published recommendations for the following viruses to be used for influenza vaccines in the 2010-2011 influenza season of the Northern Hemisphere:
o an A/California/7/2009 (H1N1)-like virus;
o an A/Perth/16/2009 (H3N2)-like virus*;
o a B/Brisbane/60/2008-like virus.
* A/Wisconsin/15/2009 is an A/Perth/16/2009 (H3N2)-like virus and is a 2010 Southern Hemisphere vaccine virus.

September 8, 2010, 4:00 PM ET
http://www.cdc.gov/flu/international/activity.htm