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Published Date: 2011-10-21 14:12:39
Subject: PRO/EDR> Influenza (61): WHO update
Archive Number: 20111021.3140

INFLUENZA (61): WHO UPDATE
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: Fri 21 Oct 2011
Source: WHO Surveillance Monitoring [edited]
http://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance/en/index.html

Influenza Update number 145
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Summary
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- Influenza activity in the temperate regions of the northern
hemisphere remains low or undetectable.
- Influenza activity in the tropical zone is active in a few countries
of the Americas (Cuba, Honduras, and El Salvador), central Africa
(Cameroon), and Southern and South East Asia (Bangladesh, Cambodia,
Thailand, Lao People's Democratic Republic, and Viet Nam.
- Transmission in South Africa and South America remains low and the
season appears largely over.
- Influenza activity has peaked in Australia and New Zealand, though
there are regional variations in the timing of the peaks and the
season has not yet finished. Australia continues to see regional
differences in the predominant virus subtype.

Countries in the temperate zone of the northern hemisphere
----------------------------------------------------------
The countries in the northern hemisphere temperate zone are still in
their inter-seasonal period for influenza. Many of the countries
suspend surveillance activities during the summer months and have now
resumed influenza monitoring at the start of October but none report a
start of active community transmission of influenza.

Countries in the tropical zone
------------------------------
- Southern Asia circulation of influenza viruses (snapshot)
http://www.who.int/influenza/surveillance_monitoring/updates/2011_10_21_influenza_southern_asia_circulation_main.pdf

In the tropical countries of the Americas, generally low levels of
influenza transmission are reported. In the Dominican Republic,
influenza transmission is reported to be sustained at a low level,
with influenza type B now the most common influenza virus detected.
Influenza virus detections in Cuba, Honduras, and El Salvador appear
to have peaked in mid to late September 2011, with influenza A(H3N2)
as the predominant strain. In Panama, influenza A(H1N1)pdm09
[previously influenza A(H1N1)2009 and H1N1(2009) -- see comment] has
been consistently the predominant virus detected since late June 2011.
Other Central American countries reported no or very low influenza
activity. Countries of the tropical area of South America have
reported low or undetectable levels of influenza transmission. The
previously reported transmission of predominantly influenza
A(H1N1)pdm09 in Bolivia has now returned to baseline level, after its
peak in mid September 2011.

In sub-Saharan Africa, influenza transmission has continued in
Cameroon, primarily influenza B with smaller amounts of influenza
A(H1N1)pdm09 and increasing numbers of influenza A(H3N2) in recent
weeks, and peaking in week 38 [19-25 Sep 2011]. In eastern Africa,
continuous low level transmission of a mixture of influenza type B,
A(H3N2), and A(H1N1)pdm09 since the peak of transmission in March is
reported.

Influenza transmission in tropical Asia has continued to be active in
localized areas. Transmission of primarily influenza B was reported in
India, Bangladesh and Cambodia, though in India it has now returned to
low levels. Circulation of influenza A(H3N2) persist in Thailand and
Lao People's Democratic Republic after their peaks in early and late
September 2011, respectively. Viet Nam also reports sustained
transmission of predominantly influenza A(H1N1)pdm09 which has been
continuous since the beginning of 2011.

Countries in the temperate zone of the southern hemisphere
----------------------------------------------------------
South America

- Temperate South America circulation of influenza viruses (snapshot)
http://www.who.int/influenza/surveillance_monitoring/updates/2011_10_21_influenza_temperate_south_america_circulation_main.pdf

Influenza activity has continued to decline in the temperate regions
of South America and are approaching baseline, intra-seasonal levels.
Co-circulation of influenza type A(H3N2) and A(H1N1)pdm09 persist in
Argentina and Chile, though a large proportion of viruses there are
not subtyped, while influenza A(H3N2) is predominant in Paraguay. The
overall severity of influenza of this season in Argentina and Chile
has been similar to that observed during previous seasons, with regard
to numbers of influenza-like illness (ILI) (Chile and Argentina),
percentages of respiratory admissions in children younger than 5 years
(Chile), and the numbers of pneumonia cases (Argentina). In Uruguay,
the proportion of severe acute respiratory infection (SARI)
hospitalizations, ICU admissions and deaths remained below 5 per cent
in the 1st week of October 2011, a rate which is comparable to the
same period in the 2010 season. In Paraguay, the proportion of ILI
consultations decreased to 6 per cent and the proportion of SARI
hospitalizations, ICU admissions and deaths remained below 10 per cent
in the last week of September 2011.

Southern Africa
- Southern Africa circulation of influenza viruses (snapshot)
http://www.who.int/influenza/surveillance_monitoring/updates/2011_10_21_influenza_southern_africa_circulation_main.pdf

Influenza transmission in South Africa has continued at low level
since peaking in early June 2011.

Australia, New Zealand and South Pacific

- Oceania Melanesia and Polynesia circulation of influenza viruses
(snapshot)
http://www.who.int/influenza/surveillance_monitoring/updates/2011_10_21_influenza_oceania_circulation_main.pdf

The influenza season is still ongoing in Australia and New Zealand,
though activity is declining. ILI consultation rates have started to
decline nationally in Australia. In the week ending 2 Oct 2011, the
national ILI consultation rate to sentinel general practitioners was 9
cases per 1000 consultations, down from 12 cases per 1000 in the
previous report. Respiratory illness presentations to Western
Australia Emergency Departments decreased compared to the previous
fortnight, though they remained well above baseline levels. ILI
presentations to New South Wales Emergency Departments were similar to
the previous week, and activity was reported as being below the usual
range for this time of year. 58 per cent of ILI presentations occurred
in people aged 25-44 and 55-64. Total admissions from New South Wales
Emergency Departments to critical care units for ILI and pneumonia
decreased this week, and remained within the usual range for this time
of year.

Up to 30 Sep 2011, there have been 24 049 laboratory confirmed
notifications of influenza diagnosed so far. Nationally, weekly
notifications for this season have peaked in early August 2011, though
the timing of the peaks varied between different regions. This number
exceeds that reported in previous years other than the 2009 pandemic
year.

The Influenza Complications Alert Network Sentinel Hospital System in
Victoria, South Australia, Western Australia, and the Australia
Capitol Territory has reported 223 hospitalizations including 31 ICU
admissions associated with influenza from 1 May 2011 to 30 September
2011. Almost half of the hospitalizations and 45 per cent of ICU
admissions have been associated with influenza A(H1N1)2009 infection.
The mean age of patients hospitalized has been 51 years.

The majority of states and territories have reported mostly influenza
A(H1N1)pdm09 with co-circulation of influenza B. However, in the
Northern Territory this fortnight notifications of influenza A(H3N2)
represent 70 per cent of their notifications, and nationally the
majority of A(H3N2) notifications are being reported from the Northern
Territory, Queensland, and Western Australia. In Tasmania and New
South Wales influenza B represents around half of their notifications,
and the proportion of influenza B in Queensland appears to be
increasing.

In New Zealand, the rate of national ILI consultations has decreased
to 29.0 per 100 000 (108 ILI consultations), which is below the
baseline rate of 50 per 100 000 consultations. Influenza type A(H3N2),
A(H1N1)pdm09 and B viruses co-circulate in the population.

Maps and graphs
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- Global circulation of influenza viruses (snapshot)
http://www.who.int/influenza/surveillance_monitoring/updates/2011_10_21_influenza_global_circulation.pdf

- Northern hemisphere circulation of influenza viruses (real-time)
http://gamapserver.who.int/gareports/Default.aspx?ReportNo=5&Hemisphere=Northern

- Southern hemisphere circulation of influenza viruses (real-time)
http://gamapserver.who.int/gareports/Default.aspx?ReportNo=5&Hemisphere=Southern

--
communicated by:
ProMED-mail rapporteur Marianne Hopp

[Interested readers are recommended to access the figures referenced
above to gain a rapid appreciation of the current influenza situation.
Other maps and graphs (real time) are available at the WHO website.

WHO has now adopted new standard nomenclature for the 2009 influenza
A(H1N1) pandemic virus following the recommendations of a recent WHO
Consultation on the Composition of Influenza Vaccines. In this and
future publications, the nomenclature used will be: influenza
A(H1N1)pdm09. This will replace the previously used influenza
A(H1N1)2009 and H1N1(2009). See the Weekly Epidemiological Record
(WER), 21 Oct 2011, 86(43): 469-80;
http://www.who.int/wer/2011/wer8643/en/index.html. - Mod.CP]

See Also