INFLUENZA (33): WHO GLOBAL UPDATE

INFLUENZA (33): WHO GLOBAL UPDATE
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Date: Fri 24 May 2013
Source: WHO Surveillance and Monitoring, Influenza updates [edited]
<http://www.who.int/influenza/surveillance_monitoring/updates/2013_05_24_surveillance_update_186.pdf>


Influenza update no 186
-----------------------
Summary
-------
- Influenza activity in the northern hemisphere temperate zones
decreased to low levels with some continued transmission in some areas
including Canada and Egypt.
- In the tropical areas, influenza activity varied but was similar to
previous weeks. Madagascar reported to be in an epidemic since the
beginning of April [2013].
- Influenza activity in the southern hemisphere was low with a slight
increase reported in South Africa.
- For information on H7N9 please see
<http://who.int/influenza/human_animal_interface/influenza_h7n9/en/index.html>.
- A summary review of influenza activity in the northern hemisphere
influenza season will be published in the World Epidemiological Report
on 31 May 2013.

Countries in the temperate zone of the northern hemisphere
----------------------------------------------------------
Influenza activity in the northern hemisphere temperate zones has
decreased to low levels but with some continued transmission in some
areas. In Canada, where the influenza season has been prolonged due to
the late season circulation of influenza type B, type B transmission
continued at decreasing levels in early May [2013]. A number of
influenza case-associated hospitalizations were also reported, nearly
all of them associated with influenza type B.

In the United States of America, Europe, and northern Asia
transmission has returned to inter seasonal levels. In North Africa,
some low grade persistence of influenza type B and influenza
A(H1N1)pdm09 was reported in early May [2013] following a peak of
transmission of both viruses in early April [2013].

A summary review of the northern hemisphere 2012-13 influenza season
will be published in the World Epidemiological Report on 31 May.

Countries in the tropical zone
------------------------------
Tropical countries of the Americas/Central America and the Caribbean
--------------------------------------------------------------------
In the Central America and Caribbean regions and tropical South
America, influenza activity has remained similar with mainly influenza
A(H1N1)pdm09. In Brazil influenza activity overall decreased, but the
trend in SARI cases with mainly influenza A(H1N1)pdm09 increased,
mainly in in the southern areas. Ecuador in contrast reported
decreased activity with A (H3N2).

Central African tropical region
-------------------------------
A few countries in the Central African tropical region have reported
low grade, persistent influenza transmission with varying proportions
of all three virus types over the past several weeks. Madagascar
reported also an increasing level in influenza activity since the
beginning of April [2013] with influenza A(H1N1)pdm09 as the most
common virus.

Tropical Asia
-------------
Influenza transmission in southern Asia was similar to previous week
with co-circulation of all 3 viruses. Transmission in India appears to
have peaked in late March [2013] and was primarily associated with
influenza A(H1N1)pdm09 with slightly smaller numbers of A(H3N2) and
influenza B viruses. In Sri Lanka influenza activity has reached the
highest level throughout this season with influenza B and influenza
A(H1N1)pdm09. Influenza transmission in southern China peaked in
mid-March and was almost entirely associated with influenza
A(H1N1)pdm09.

Countries in the temperate zone of the southern hemisphere
----------------------------------------------------------
South Africa seems to have an increase in recent weeks in specimens
testing positive for influenza with 37.5 per cent testing positive for
influenza in week 19 [ending 11 May 2013], which might indicate the
start of the [southern hemisphere] flu season. The vast majority is
due to influenza A(H1N1)pdm09. Few influenza B and one influenza
A(H3N2) virus were detected in weeks 18 and 19 [28 Apr-11 May 2013].

In Australia, New Zealand and the Pacific Islands, ILI activity
remained low with few samples testing positive for influenza. During 5
to 11 May 2013 in Australia, of 208 ILI samples received, 1 was
positive for influenza A (H1N1) pdm09 and 1 influenza B. In New
Zealand, during 5-12 May 2013, influenza activity continued to remain
low and below the baseline.

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[Interested readers are recommended to access the original text via
the source URL to view the graphical presentation of the data
associated with the text. Further information can be obtained via the
following links.

Epidemiological influenza updates:
<http://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance>
Epidemiological influenza updates archives 2012:
<http://www.who.int/influenza/surveillance_monitoring/updates/GIP_surveillance_2012_archives>
Virological surveillance updates:
<http://www.who.int/influenza/gisrs_laboratory/updates/summaryreport>
Virological surveillance updates archives:
<http://www.who.int/influenza/gisrs_laboratory/updates/en/index.html>

It seems that globally influenza activity has subsided, which gives
substance to the suggestion that the decline of avian A/H7N9 virus
infection in China may indeed be a consequence of seasonal factors. -
Mod.CP]

[see also:
Influenza (32): WHO global update 20130513.1710725
Influenza (31): H3N2 pandemic potential 20130513.1710144
Influenza (30): global update 20130426.167441
Influenza (26): European region update 20130322.1599132
Influenza (25): WHO global update 20130316.1590054
Influenza (24): USA, vaccine effectiveness, corr. 20130307.1576157
Influenza (24): USA, vaccine effectiveness 20130306.1574072
Influenza (23): WHO global update 20130301.1566344
Influenza (18): European region update 20130208.1535572
Influenza (10): European region update 20130126.1516108]
.................................................cp/mj/sh
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