ProMed-INFLUENZA (50): AUSTRALIA (NEW SOUTH WALES), H275Y MUTATION CLUSTER

[Tonka]

SourceroMed
http://www.promedmail.org/pls/otn/f..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,89966


Archive Number 20110825.2594
Published Date 25-AUG-2011
Subject PRO/EDR> Influenza (50): Australia (NS) H275Y mutation cluster
INFLUENZA (50): AUSTRALIA (NEW SOUTH WALES), H275Y MUTATION CLUSTER
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: Thu 24 Aug 2011
From: Kate Hardie <Kate.Hardie@hnehealth.nsw.gov.au>


A cluster of oseltamivir-resistant A(H1N1)2009 influenza cases with
onset between May and August 2011 has been detected in the Hunter
region of New South Wales (NSW), Australia.

Viruses from 25 of 184 (14 percent) A(H1N1)2009 cases from the Hunter
New England region exhibited highly reduced oseltamivir sensitivity
due to the H275Y substitution in the neuraminidase. The H275Y mutation
is a well-established substitution previously reported to confer
oseltamivir resistance in N1 neuraminidases and was present in the
widespread oseltamivir resistant pre-pandemic seasonal A(H1N1) virus.

15 of the 1st 16 cases lived within a 50-km radius of the regional
centre of Newcastle. 16 of the 25 patients have been interviewed, and
none had received oseltamivir prior to influenza specimen collection.
Only 5 were hospitalised at the time of specimen collection. None of
the 16 had a history of immune suppression; 3 cases were pregnant. No
one was admitted to ICU or had a fatal outcome. Further interviews
with cases and virological analyses are ongoing.

--
Communicated by:
Kate Hardie
Hunter New England Population Health
NSW, Australia
<Kate.Hardie@hnehealth.nsw.gov.au>

Aeron Hurt
WHO Collaborating Centre for Reference and Research on Influenza
Melbourne, Australia

Noelene Wilson
Nicole Gehrig Hunter Area Pathology Service
NSW, Australia

[ProMED-mail thanks Kate Hardie and colleagues for communicating the
discovery of this cluster of oseltamivir-resistance cases in the
Hunter region of New South Wales.

According to the most recent WHO weekly update on oseltamivir
resistance in influenza A(H1N1)2009 viruses, dated 13 Jul 2011, the
cumulative total of cases since April 2009 was 565. It was concluded
that the overall incidence of viruses resistant to antivirals remained
very low, with no recent reports of case clusters. The preceding
report from New South Wales is significant in this respect.

A map of the Hunter Valley region of New South Wales can be accessed
at: <http://www.sydney-australia.biz/maps/hunter-valley-map.php>. -
Mod.CP]

[see also:
Influenza (44): WHO update 20110716.2155]
.................................................cp/msp/dk
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[Vibrant62]

Re: ProMed-INFLUENZA (50): AUSTRALIA (NEW SOUTH WALES), H275Y MUTATION CLUSTER

Tamiflu-Resistant Flu Outbreak Reported in Australia’s Newcastle, WHO Says
http://www.bloomberg.com/news/2011-...ported-in-australia-s-newcastle-who-says.html
Jason Gale - Aug 25, 2011

More than two dozen cases of H1N1 swine flu resistant to Roche Holding AG (ROG)’s Tamiflu pill were reported in Australia in the largest outbreak of the drug- evading influenza strain.

Viruses from 25 of 184 patients in the Newcastle area of eastern Australia infected with the pandemic germ had a genetic mutation that reduces the potency of Tamiflu, scientists said in a report distributed today by the International Society for Infectious Diseases’ ProMED-mail program.

The cases, first reported in May, raise concern that the resistant strain may spread, leaving doctors without their preferred treatment for influenza. GlaxoSmithKline Plc (GSK)’s Relenza drug is effective against the mutant strain, which is still found in the Newcastle area, according to the World Health Organization’s Collaborating Centre for Influenza in Melbourne.

“As long as it’s isolated to Newcastle and that region, it’s not so much of a problem,” said Ian Barr, the center’s deputy director, in a telephone interview today. “If it spreads further, it might be a concern. Fortunately, we’re heading toward the end of our flu season.”

The cluster of cases with the mutant virus is the largest reported outbreak globally to date, and shows the new variant is capable of being transmitted efficiently in the absence of drug pressure, said Jennifer McKimm-Breschkin, a virologist at the Commonwealth Science and Industrial Research Organization in Melbourne, who studies antiviral resistance.

‘Fit and Transmissible’
“It’s clearly fit and transmissible,” she said in a telephone interview today. “It would be concerning having seen such a large cluster like that.”

None of those infected had taken Tamiflu prior to being tested for flu. Of 16 patients interviewed by the scientists, none had a history of immune suppression, which contributes to drug resistance. None of the patients was admitted to an intensive care unit or died from the infection, the report said.

Further interviews with cases and virological analyses are ongoing, the scientists said.

Snip...

Sporadic Resistance
Studies have shown that Tamiflu-resistant bugs develop sporadically in 0.4 percent to 4 percent of adults and children treated for seasonal influenza, according to Basel, Switzerland- based Roche.

The outbreak of resistant H1N1 in Newcastle probably emerged in a treated patient who passed the infection onto others, McKimm-Breschkin said.
Ten to 15 percent of H1N1 infections in the Hunter Valley area of New South Wales state, which includes Newcastle, are resistant to Tamiflu, WHO’s Barr said. The seasonal flu vaccine protects against the new flu variant, as well as influenza type B, the main strain circulating in the Newcastle area, he said.

snip...


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