Pandemic (H1N1) 2009 – update 106

Weekly update

25 June 2010 — As of 20 June, worldwide more than 214 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including over 18209 deaths.

WHO is actively monitoring the progress of the pandemic through frequent consultations with the WHO Regional Offices and Member States and through monitoring of multiple sources of information.

Situation update:

Worldwide, overall pandemic and seasonal influenza activity remains low. Active transmission of pandemic influenza virus persists in parts of the tropics, particularly in the Caribbean, West Africa, and South and Southeast Asia. Pandemic and seasonal influenza viruses have been detected only sporadically during the early part of winter in the temperate regions of the southern hemisphere. Global circulation of seasonal influenza virus type B viruses has declined substantially and persists at low levels in parts of East Asia, Central Africa, and Central America. During the past month, seasonal influenza H3N2 viruses have been detected at low levels across parts of East Africa and South America.

In most countries of the temperate zone of the southern hemisphere (Chile, Argentina, South Africa, Australia, and New Zealand) pandemic and seasonal influenza viruses have been detected only sporadically during the first two weeks of June 2010 and overall levels of respiratory disease in the population remain low. In Chile, during the second week of June, approximately 1% samples tested positive for influenza (the majority were pandemic influenza virus). In Argentina, small numbers of influenza type B viruses were detected during early June 2010. In both Chile and Argentina, respiratory syncitial virus (RSV) continued to be the predominant circulating respiratory virus. In South Africa, very small numbers of seasonal H3N2 and type B viruses were detected since the beginning of June 2010. In both Australia and New Zealand, levels of ILI are below recent historical seasonal levels and there have been only sporadic detections of seasonal or pandemic influenza virus during the first half of June 2010.

In Asia, the most active areas pandemic influenza virus transmission currently are in parts of southern India, Bangladesh, Singapore, and Malaysia. In India, there have been recent reports of increasing pandemic influenza activity in the southern state of Kerala, including reports of small numbers of severe and fatal cases, particularly among pregnant women; the extent of illness in the community is currently being assessed. In Bangladesh, pandemic and seasonal influenza type B viruses continued to co-circulate at low levels during early June 2010. In Thailand, limited data suggests that there continues to be low levels of pandemic and seasonal influenza virus co-circulating in parts of the country. In Singapore, during the third week of June 2010, levels of ARI declined below warning levels and the proportion of patients with ILI testing positive for pandemic influenza virus fell from 28% to 19%. In Malaysia, limited data suggests that overall pandemic influenza activity declined throughout June 2010 as pandemic virus continued to circulate at low levels. Throughout East Asia, overall pandemic and seasonal activity remained very low to sporadic. In China and Japan, levels of ILI remained at or below baseline levels for the summer months. Low and declining levels of seasonal influenza type B viruses continued to circulate across China, Hong Kong SAR (China), and Chinese Taipei.

In the tropical regions of the Americas, overall pandemic and seasonal influenza activity remained very low, except in Cuba and Colombia, where low levels of pandemic influenza virus continue to circulate (approximately 8% of respiratory samples tested positive for pandemic influenza in both countries during the early part of June 2010). In Cuba, pandemic influenza virus transmission remains active but has declined substantially since peaking during mid-April to mid-May 2010; no new fatal cases have been reported over the past four reporting weeks. In Colombia, persistent but low level circulation of pandemic influenza virus has increased slightly since late May 2010; however, the overall level of respiratory diseases in the population was reported to be low to moderate during mid June 2010. In several countries of the region, there has been recent circulation of seasonal influenza viruses including type A (Venezuela during May 2010) and B (Bolivia during March and May 2010; El Salvador during late May and early June 2010). Variable ongoing co-circulation of other respiratory viruses, including RSV, continues to be reported across the region.

In sub-Saharan Africa, pandemic and seasonal influenza activity has been limited to several countries. Ghana, in West Africa, continued to have active circulation of pandemic influenza virus long after overall activity peaked during early April 2010; the proportion of respiratory samples testing positive for pandemic influenza virus increased from 16% to 23% during the first two weeks of June 2010. Seasonal influenza type B viruses continue to circulate in parts of central and southern Africa, most notably in Cameroon. As reported in previous updates, small numbers of seasonal H3N2 viruses continue to be detected across Africa, particularly in eastern Africa; the most recent detections have been reported in Ghana, Kenya, and South Africa during the second week of June 2010. The persistence of H3N2 in this area over time very likely represents sustained community transmission of the virus.

Overall, in the temperate regions of the northern hemisphere (North America and Europe), pandemic and seasonal influenza viruses have been detected sporadically or at very low levels during the past month.

The Global Influenza Surveillance Network (GISN) continues monitoring the global circulation of influenza viruses, including pandemic, seasonal and other influenza viruses infecting, or with the potential to infect, humans including seasonal influenza. For more information on virological surveillance and antiviral resistance please see the weekly virology update (Virological surveillance data, below).

Weekly update (Virological surveillance data)

Weekly update on oseltamivir resistance to pandemic influenza A (H1N1) 2009 viruses [pdf 16kb]

*Countries in temperate regions are defined as those north of the Tropic of Cancer or south of the Tropic of Capricorn, while countries in tropical regions are defined as those between these two latitudes.

**Abbreviations: influenza-like-illness (ILI), acute respiratory infection (ARI), and severe acute respiratory infection (SARI)

WHO Clinical Management Guidelines for Human infection with Pandemic (H1N1), 2009:

WHO Guidelines for Pharmacological Management of Pandemic (H1N1) 2009 Influenza and other Influenza Viruses:

MAP OF INFLUENZA ACTIVITY AND VIRUS SUBTYPES (WEEK 23: 30 MAY – 12 JUNE 2010)

Map of influenza activity and virus subtypes [png 259kb]
Description: Displayed data reflect the most recent data reported to Flunet (www.who.int/FluNet), WHO regional offices or on Ministry of health websites in the last 2 weeks. The percent of specimens tested positive for influenza includes all specimens tested positive for seasonal or pandemic influenza. The pie charts show the distribution of virus subtypes among all specimens that were tested positive for influenza. The available country data were joined in larger geographical areas with similar influenza transmission patterns to be able to give an overview (http://www.who.int/csr/disease/swineflu/transmission_zones/en)

Qualitative indicators (Week 29 to Week 23: 13 July 2009 – 12 June 2010)

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.

Human infection with pandemic (H1N1) 2009 virus: updated interim WHO guidance on global surveillance

The maps below display information on the qualitative indicators reported. 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.

List of definitions of qualitative indicators

Geographic spread of influenza activity

Map timeline

Trend of respiratory diseases activity compared to the previous week

Map timeline

Intensity of acute respiratory diseases in the population

Map timeline

Impact on health care services

Map timeline

Laboratory-confirmed cases of pandemic (H1N1) 2009 as officially reported to WHO by States Parties to the IHR (2005) as of 20 June 2010

Map of affected countries and deaths

The countries and overseas territories/communities that have newly reported their first pandemic (H1N1) 2009 confirmed cases since the last web update (No. 105): none.

The countries and overseas territories/communities that have newly reported their first deaths among pandemic (H1N1) 2009 confirmed cases since the last web update (No. 105): none.

*The reported number of fatal cases is an under representation of the actual numbers as many deaths are never tested or recognized as influenza related

**No update since 7 March 2010

***No update since 23 May 2010