June 25, 2010. WHO Updates Information About H1N1 Influenza
| SOURCE: | World Health Organization |
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.
*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)
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