16 Aug 2013

Influenza Update N° 192, 16 August 2013 (WHO, edited)

[Source: World Health Organization, full PDF document: (LINK). Extracts.]

Influenza Update N° 192, 16 August 2013

 

Summary

  • Influenza activity in the northern hemisphere temperate zones remained at inter-seasonal levels. The United States of America reported 16 cases of human infection with influenza A(H3N2)v so far this year, with the first case reported in June. More details can be found at http://www.cdc.gov/flu/swineflu/h3n2v-cases.htm.
  • In most regions of tropical Asia influenza activity decreased.
  • In Central America and the Caribbean regions, influenza and Respiratory Syncytial Virus (RSV) transmission showed a decreasing trend. RSV and influenza A(H1N1)pdm09 were the main respiratory viruses reported. In Nicaragua transmission activity has decreased again after a sharp increase of transmission activity due to influenza A(H3N2) in the beginning of July.
  • In tropical South America, influenza A(H1N1)pmd09 remained the most commonly detected respiratory virus in the region. A sharp increase in influenza A(H1N1)pdm09 transmission has been observed in Peru in the middle of July. Influenza activity is decrasing in Colombia, Venezuela, Bolivia and Brazil.
  • Influenza transmission has peaked in the southern cone of South America and in South Africa in late June. In all of those areas, transmission was primarily associated with influenza A(H1N1)pdm09. In Australia and New Zealand, numbers of influenza viruses detected and rates of influenza-like illness have been lower than in previous years, but have not yet definitively peaked. Influenza A(H3N2) and type B have been much more commonly detected than A(H1N1)pdm09 in both countries.
  • As of 11 August, a total of 135 cases of influenza A(H7N9) virus infection have been reported. For more details see: http://who.int/influenza/human_animal_interface/influenza_h7n9/en/index.html

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Countries in the temperate zone of the northern hemisphere

North America

Overall influenza activity in North America remained at low levels throughout most of the region.

In Canada and the United States of America (USA), influenza activity remained at inter-seasonal levels.

The USA has reported 16 human infections with influenza A(H3N2)v virus in 2013 since the first case in June. For more details see http://www.cdc.gov/flu/swineflu/h3n2v-cases.htm.

 

Europe

Influenza activity in Europe remained at inter-seasonal levels. Consultation rates for ILI and ARI were at low levels for all countries in the region. None of the specimens collected from sentinel sites tested positive for influenza.

 

Northern Africa and the Western Asia region

Influenza activity was low in the Northern Africa and western Asia regions. Influenza A(H1N1)pdm09 has been detected throughout the season in most countries in western Asia, with the exception of Jordan which reported a majority of influenza B.

 

Northern Asia

Influenza activity in the temperate region of Asia has been at inter-seasonal levels since late May.

As of 11 August 2013, 135 cases of influenza A(H7N9) have been identified, of which 44 have died. This represents on additional case since the last update. more and updated information is posted at: http://who.int/influenza/human_animal_interface/influenza_h7n9/en/index.html

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Countries in the tropical zone

Tropical countries of the Americas/Central America and the Caribbean

Influenza activity in Caribbean and Central America was decreasing. All samples tested positive for influenza were influenza type A , no influenza B has been detected.

In El Salvador, Panama and Cuba activity was decreasing, influenza A(H3N2) was the most commonly detected Influenza virus.

In Cuba recently a change in circulating virus strains from predominantly influenza A(H1N1)pmd09 to predominantly influenza A(H3N2) has been observed.

In Nicaragua a sharp increase in transmission with predominantly influenza A(H3N2) was observed in the second week of July, but has decreased since then.

Transmission was still high in Costa Rica. Over 30% of samples were tested positive for influenza, all of them are positive for influenza A, of those that are subtyped, Influenza A(H1N1)pdm09 was most common.

In tropical South America, influenza transmission overall was decreasing but a sharp increase in influenza A(H1N1)pdm09 transmission has been observed in Peru in the middle of July. Influenza A(H1N1)pmd09 remained the most commonly detected respiratory virus in the region. Activity was decrasing in Bolivia, Brazil, Colombia and Venezuela.

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Central African tropical region

Cameroon, Cote d’Ivoire, Ghana and Kenya, reported low influenza activity.

Cote d’Ivoire reported higher activity of influenza B, whereas in Cameroon, there was higher activity of A(H1N1)pdm09 and in Ghana higher activity of influenza A(H3). After peaking at the end of May, influenza activity in Madagascar continued to decrease.

 

Tropical Asia

Influenza transmission in southern Asia and South East Asia remained consistently low for most countries.

The influenza activity in Cambodia, Thailand and Viet Nam showed a decreasing trend after several weeks of higher activity. Both influenza A(H3N2) virus and influenza A(H1N1)pdm09 were reported in this area.

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Countries in the temperate zone of the southern hemisphere

Temperate countries of South America

Influenza and RSV activity showed a decreasing trend, most commonly virus detected in temperate South America continued to be RSV. Influenza virus transmission has continued to decrease since peaking in June and has primarily been associated with influenza A(H1N1)pdm09 with exception of Paraguay, where influenza A(H3N2) has been the predominant strain.

In Chile, the national ILI consultation rate continued to show a decline. RSV remained the most common virus detected. Among 1650 samples collected, 4% were positive for influenza viruses. Among the positive specimens, the large majority have been influenza A(H1N1)pdm09 with smaller numbers of A(H3N2) and influenza type B.

In Argentina, the number of ILI cases were higher throughout the season than average for the previous 5 years but start to decrease now. Of the 1700 samples analyzed, 13% were positive for influenza. Among samples positive for influenza viruses, the large majority have been influenza A(H1N1)pdm09.

In Paraguay, while ILI activity decreased, SARI hospitalizatons did not decrease yet. Of 197 samples analyzed, 36% were positive for influenza. RSV and influenza (H3N2) predominated.

In Uruguay Influenza activity continues to decrease, RSV and influenza A(H1N1)pdm09 are the predominant viruses.

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Temperate countries of Southern Africa

Influenza activity in South Africa has continued to decrease since the peak of the season in early June. Specimens collected from sentinel sites indicate that Influenza A(H1N1)pmd09 remained the most commonly detected influenza subtype, although small numbers of influenza A(H3) and influenza B have also been reported.

 

Oceania, Melanesia and Polynesia

Australia, New Zealand and the Pacific Islands continued to report low influenza and ILI activity, but with an increasing trend.

During the week ending 21 July 2013 in Australia, the ILI consultation rate continued to slowly increase but was still slightly lower than the usual rate for this time of year.

In New Zealand, during 29 July to 4 August 2013, influenza activity continued to remain below the baseline threshold, but with increasing trends. Sixty-three out of 236 samples received were positive for influenza: 40 were influenza B, 10 were influenza A(H3N2), 9 were influenza A(H1N1)pdm09 and 4 influenza A (not subtyped).

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Source of data

The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.

The updates are based on available epidemiological and virological data sources, including FluNet (reported by the Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.

 

Link to web pages

Contact fluupdate@who.int

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