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WHO: Week 25 Virological Update

 


# 4712

 

 

The World Health Organization has released their latest pandemic H1N1 update (#108), current through July 4th.  

 

A brief excerpt from the much longer report:

Worldwide, overall pandemic influenza activity remains low. Active circulation of pandemic influenza virus persists in areas of the tropics, particularly in South and Southeast Asia, the Caribbean and West Africa. Overall pandemic and seasonal influenza activity has remained low during the early part of the current winter season in the temperate zone of the southern hemisphere.

Low levels of seasonal influenza (H3N2 and type B) viruses were detected during June 2010 in South Africa, while Chile, Australia, and New Zealand, have all recently detected low levels of predominantly pandemic influenza virus. Increasing seasonal influenza activity has also recently been observed in several countries of Central America.

 

The virological update – which is perhaps of greater interest – runs a week behind, and deals with June 20th-June 26th.

 

Here is the latest graphic showing the breakdown of virus sampling from selected countries.

 

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Although the total number of influenza cases remains low,we continue to see scattered reports of the detection of seasonal H3N2 along with the novel H1N1 and influenza B strains.

 

The graph below shows the breakdown of viral specimens in the the southern hemisphere since the start of 2010.

 

Weekly update (Virological surveillance data)

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Summary on week 25
  • Overall influenza activity has remained at low levels in most parts of the world.
  • In the Northern Hemisphere the number of influenza type B virus detections exceeded that of influenza A.
  • In the Southern Hemisphere, there is an observation of increasing number of influenza A virus detections with co-circulation of pandemic A(H1N1) and seasonal A(H3N2) viruses.

Global Virological Surveillance

At low levels, influenza B viruses continued to be predominating in some countries and areas of Northern Hemisphere, including China (69.3% of all influenza detections) and Russian Federation (93.7%). Sporadic influenza B activity has also been observed in some other countries.

 

Sporadic influenza A activity was reported in some countries in the Southern Hemisphere, including Australia, Brazil and South Africa. The proportion of A(H3N2) increased in South Africa (53% of all detections) while pandemic A(H1N1) virus was reported as predominant in Brazil (93.8%). In Australia the proportion of co-circulation of pandemic A(H1N1) and seasonal A(H3N2) viruses is very similar (58.3% and 41.7% of all detection, respectively).

 

FluNet Report

The total number of specimens reportedly positive for influenza viruses by National Influenza Centres (NICs) from 29 countries was 356. Of these, 194 (54.5%) were typed as influenza A and 162 (45.5%) as influenza B.

 

From the start of the pandemic in 19 April 2009 to 26 June 2010, the total number of specimens reported positive for influenza by NIC laboratories was 647,378*. Of these, 490,415 (75.8%) were pandemic A(H1N1), 8,946 (1.4%) were seasonal A(H1N1), 33,509 (5.2%) were A(H3N2), 80,737(12.5%) were A (not subtyped) and 33,645(5.2%) were influenza B.

 

Related Post:

Influenza Activity
Pandemic

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