Pandemic (H1N1) 2009 - update 63

Weekly update

In the southern hemisphere, most countries (represented by Chile, Argentina, New Zealand, and Australia) appear to have passed their peak of influenza activity and have either returned to baseline levels or are experiencing focal activity in later affected areas; while a few others (represented by South Africa and Bolivia) continue to experience high levels of influenza activity.

Many countries in tropical regions (represented by Central America and tropical regions of Asia), continue to see increasing or sustained high levels of influenza activity with some countries reporting moderate strains on the healthcare system. In temperate areas of the northern hemisphere (represented by North America, Europe, and Central Asia), influenza and respiratory disease activity remains low overall, with some countries experiencing localized outbreaks. In Japan, the level of influenza activity has passed the seasonal epidemic threshold, signaling a very early beginning to the annual influenza season.

Pandemic H1N1 influenza virus continues to be the predominant circulating strain of influenza, both in the northern and southern hemisphere. Antiviral susceptibility testing has increased in several countries, confirming that pandemic H1N1 influenza virus remains sensitive to the antiviral oseltamivir, except for sporadic reports of oseltamivir resistant pandemic H1N1 virus detailed in the previous web update (No. 62).

Qualitative indicators (Week 29 to Week 33: 13 July - 16 August 2009)

The qualitative indicators monitor: the global geographic spread of influenza, trends in acute respiratory diseases, the intensity of respiratory disease activity, and the impact of the pandemic on health-care services.

The maps below display information on the qualitative indicators reported during weeks 29 to 33. Information is available for approximately 60 countries each week. Implementation of this monitoring system is ongoing and completeness of reporting is expected to increase over time.

Geographic spread of influenza activity

Trend of respiratory diseases activity compared to the previous week

Intensity of acute respiratory diseases in the population

Impact on health care services during week 31 and week 32

Virology data update as of 16 August 2009

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Laboratory-confirmed cases of pandemic (H1N1) 2009 as officially reported to WHO by States Parties to the IHR (2005) as of 23 August 2009

The countries and overseas territories/communities that have newly reported their first pandemic (H1N1) 2009 confirmed case(s) since the last web update (No. 62) as of 23 August 2009 are:

Cameroon, Madagascar, and Mozambique.

*Given that countries are no longer required to test and report individual cases, the number of cases reported actually understates the real number of cases.