March 22, 2010. WHO Updates Information About H1N1 Influenza
| SOURCE: | World Health Organization |
As of 14 March 2010, worldwide more than 213 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 16813 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:
The most active areas of pandemic influenza transmission continue to be in Southeast Asia and West Africa. Limited data suggests that pandemic influenza activity may be increasing across parts of Central America and the Caribbean. Low levels of pandemic influenza virus continue to circulate across southern and south-eastern Europe and in East, West, and South Asia. Although pandemic influenza virus continues to be the predominant influenza virus circulating worldwide, seasonal influenza B viruses are predominate in East Asia, and have been detected at low levels across southeast Asia and eastern Africa.
In south and southeast Asia, the most active areas of pandemic influenza transmission continue to be in Thailand; over the past month approximately 25-30% of sentinel respiratory samples from patients with ILI and 10-35% of sentinel respiratory samples from hospitalized patients with pneumonia tested positive for influenza (predominantly pandemic H1N1, but also small numbers of seasonal B viruses). Recent pandemic influenza activity in Thailand, while associated with severe and fatal illness, does not appear to exceed activity observed during an earlier period of peak transmission between June and September 2009. In Myanmar, respiratory disease activity may be declining after a period of increased activity associated with increased detection of pandemic H1N1 cases during February 2010. In Bangladesh, an increasing trend in respiratory diseases activity was reported for the past two weeks in association with increased numbers of confirmed cases and increased geographical spread of pandemic influenza virus. In India, low level of pandemic influenza virus continues to circulate in western India.
In East Asia, pandemic influenza activity continued to decline substantially as rates of illness returned to baseline or remained low in Japan, Republic of Korea, Hong Kong (SAR), and Chinese Taipei. In China, pandemic influenza activity has waned substantially, however, influenza type B viruses continue to circulate. In Mongolia, a recent sharp increase in ILI activity was associated almost exclusively with increased circulation of influenza B viruses. In addition, increasing but low levels of circulation of seasonal influenza B viruses has been observed across other parts of East and Southeast Asia (Japan, Republic of Korea, Chinese Taipei, the Philippines, Thailand, Vietnam, Indonesia, Bangladesh). Small numbers of seasonal H3N2 viruses have also been detected in several countries of East and Southeast Asia.
In West Africa, limited data suggest that active transmission of pandemic influenza virus remains sustained across much of the region without clear evidence of a peak in activity. In Ghana, 38% of respiratory specimens collected during the past week tested positive for influenza, and of these, approximately 70% were pandemic H1N1. Limited sentinel surveillance data from Nigeria suggest that levels of ILI have increased over the past two months in conjunction with increased detections of pandemic influenza H1N1 virus. Localized outbreaks of pandemic H1N1 influenza have also been recently reported in parts of East Africa, particularly in Rwanda. Pandemic influenza virus continues to be the predominant influenza virus circulating in West and East Africa, however, small numbers of seasonal H3N2 and seasonal B viruses have also been identified.
In tropical zone of the Americas, particularly in Central America and the Caribbean, limited data suggest that pandemic influenza virus transmission may be active. Geographically regional to widespread pandemic influenza activity was reported across Central America and the Caribbean with mixed trends in the pattern of respiratory diseases activity (increasing activity in Jamaica, Bahamas, Nicaragua, Panama; and decreasing activity in Costa Rica, Guatemala). Honduras continues to report several outbreaks of respiratory disease in schools with limited laboratory confirmation of pandemic influenza virus infection. In Brazil, over the past two weeks, an increasing trend of respiratory diseases with low overall intensity was reported in association with regional spread of influenza virus.
In North Africa and Western Asia, limited data suggests that pandemic influenza virus continues to circulate at low levels across the region. An increasing trend of respiratory diseases activity in association with regional spread of influenza was reported for past three weeks in Afghanistan and the past two weeks in Iraq; however, overall intensity of activity remains low to moderate in both countries. Localized to regional spread of pandemic was also reported in Morocco, Libyan Arab Jamahiriya, Egypt, Jordan, Yemen, and Oman.
In Europe, overall pandemic influenza transmission continued to decline as low levels of pandemic virus continue to circulate in parts of eastern and south-eastern Europe. The overall percentage of sentinel respiratory specimens testing positive for influenza remained low (5.1%). Pandemic H1N1 2009 virus continues to be the predominant circulating influenza virus in the European region, except in Sweden and the Russian Federation, where seasonal influenza B viruses have been reported as co-dominant or dominant.
In the northern and the southern temperate zones of the Americas, overall pandemic influenza transmission remained low as influenza virus continued to circulate at low levels.
In the temperate zone of the southern hemisphere, overall influenza activity remained low, with sporadic detections of pandemic and seasonal influenza viruses.
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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