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2009 H1N1 Flu: International Situation Update

January 19, 2010, 3:00 PM ET

This report provides an update to the international situation as of January 15, 2010. The World Health Organization (WHO) continues to report laboratory-confirmed 2009 H1N1 flu cases and deathsExternal Web Site IconExternal Web Site Icon on its Web page. These laboratory-confirmed cases represent a substantial underestimation of total cases in the world, as most countries focus surveillance and laboratory testing only on people with severe illness. The 2009 H1N1 influenza virus continues to be the dominant influenza virus in circulation in the world. For the most recent period in which data are available, from December 27, 2009 to January 2, 2010, 82% of positive influenza specimens reported to WHO were 2009 H1N1, 0.1% were seasonal A (H1), 1.4% were A (H3), 5.7% were influenza A viruses that were not subtyped, and 10.9% were influenza B viruses. In temperate regions of the Southern Hemisphere, sporadic cases of 2009 H1N1 continue to be reported but no substantial increases in influenza activity have been observed. In the temperate and tropical regions of the Americas, H1N1 activity continues to decrease or remain low. In North Africa, 2009 H1N1 transmission remains active in Morocco, Algeria, and Egypt.  Increasing acute respiratory illness (ARI) activity and geographically regional to widespread influenza activity was reported in Nepal during December and January, and in India, 2009 H1N1 transmission has recently increased in the western states. In Europe and East Asia, 2009 H1N1 influenza activity remains geographically widespread throughout the continent, but continues to decline overall.

Selected Highlights

  • The 2009 H1N1 influenza virus is the predominant influenza virus in circulation worldwide.
  • According to WHO, the majority of 2009 H1N1 influenza isolates tested worldwide remain sensitive to oseltamivir, an antiviral medicine used to treat influenza disease. 199 2009 H1N1 isolates tested worldwide have been found to be resistant to oseltamivir – 52 of these isolates were detected in the United States.

International Resources for 2009 H1N1 Information

Health Organizations

World Health Organization (WHO) Regional Offices

Travel and 2009 H1N1 Flu

Human cases of 2009 H1N1 flu virus infection have been identified in the United States and several countries around the world. For information on 2009 H1N1 flu and travel, see the CDC H1N1 Flu and Travel website.

Reports and Publications

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