Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa

[sharon sanders]

hat tip Miso -

Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa

Aeron C. Hurt^a^,^b^,^,, Joanne Ernest^a, Yi-Mo Deng^a, Pina Iannello^a, Terry G. Besselaar^c, Chris Birch^d, Philippe Buchy^e, Malinee Chittaganpitch^f, Shu-Chun Chiu^g, Dominic Dwyer^h, Aur?lie Guigonⁱ, Bruce Harrower^j, Ip Peng Kei^k, Tuckweng Kok^l, Cui Lin^m, Ken McPhie^h, Apandi Mohdⁿ, Remigio Olveda^o, Tony Panayotou^p, William Rawlinson^q, Lesley Scott^r, David Smith^s, Holly D'Souza^t, Naomi Komadina^a, Robert Shaw^a, Anne Kelso^a and Ian G. Barr^a^,^b
<!-- authorsNoEnt --> ^aWHO Collaborating Centre for Reference and Research on Influenza, North Melbourne, Victoria, Australia
^bMonash University, Churchill, Victoria, Australia
^cNational Institute for Communicable Diseases of the National Health Laboratory Service, Sandringham, South Africa
^dVictorian Infectious Diseases Reference Laboratory, Victoria, Australia
^eInstitut Pasteur, Phnom Penh, Cambodia
^fNational Institute of Health, Nonthaburi, Thailand
^gCenter for Research and Diagnostics, Centers for Disease Control, Taiwan
^hCentre for Infectious Diseases and Microbiology, ICPMR, Westmead Hospital, NSW, Australia
ⁱPasteur Institute, New Caledonia
^jQueensland Health Forensic and Scientific Services, QLD, Australia
^kPublic Health Laboratory, Health Bureau, Macao
^lInstitute of Medical and Veterinary Science, South Australia, Australia
^mNational Public Health Laboratory, Ministry of Health, Singapore
ⁿInstitute Penyelidikan Perubatan, Kuala Lumpur, Malaysia
^oResearch Institute of Tropical Medicine, Manila, Philippines
^pSouthern Health, Victoria, Australia
^qPrince of Wales Hospital, NSW, Australia
^rCentre for Disease Control, Darwin, Australia
^sPathWest Laboratories, Perth, WA, Australia
^tAuckland Hospital, Auckland, New Zealand

<!-- authorsNoEnt -->
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Received 13 January 2009;
<!-- articleText -->revised 2 March 2009;
<!-- articleText -->accepted 4 March 2009.
<!-- articleText -->Available online 24 March 2009.
<!-- articleText -->
<!-- articleText --> Abstract

The neuraminidase inhibitors (NAIs) are an effective class of antiviral drugs for the treatment of influenza A and B infections. Until recently, only a low prevalence of NAI resistance (<1%) had been detected in circulating viruses. However, surveillance in Europe in late 2007 revealed significant numbers of A(H1N1) influenza strains with a H274Y neuraminidase mutation that were highly resistant to the NAI oseltamivir. We examined 264 A(H1N1) viruses collected in 2008 from South Africa, Oceania and SE Asia for their susceptibility to NAIs oseltamivir, zanamivir and peramivir in a fluorescence-based neuraminidase inhibition assay. Viruses with reduced oseltamivir susceptibility were further analysed by pyrosequencing assay. The frequency of the oseltamivir-resistant H274Y mutant increased significantly after May 2008, resulting in an overall proportion of 64% (168/264) resistance among A(H1N1) strains, although this subtype represented only 11.6% of all isolates received during 2008. H274Y mutant viruses demonstrated on average a 1466-fold reduction in oseltamivir susceptibility and 527-fold reduction in peramivir sensitivity compared to wild-type A(H1N1) viruses. The mutation had no impact on zanamivir susceptibility. Ongoing surveillance is essential to monitor how these strains may spread or persist in the future and to evaluate the effectiveness of treatments against them.

<!-- articleText --> Keywords: Influenza A; Oseltamivir; Tamiflu; Resistance; Neuraminidase inhibitors; H274Y; Antivirals

 

[sharon sanders]

Re: Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa

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Re: Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa
<hr style="color: rgb(204, 204, 204); background-color: rgb(204, 204, 204);" size="1"> <!-- / icon and title --> <!-- message --> http://www.nzdoctor.co.nz/news?artic...a-6cc89181bc7e
11 FEBRUARY 2009 ISSUE

Influenza warning as strains get nasty

Amanda Cameron
acameron@nzdoctor.co.nz

A more deadly strain of influenza virus circulating this year, together with rising antiviral resistance and New Zealand?s low immunisation rates, has influenza experts worried.

?The ingredients are all there for an influenza season much worse than we?ve seen before or for a long time,? says National Influenza Strategy Group (NISG) chair Anna-Marie Frost. ?It?s like a bit of a bonfire ready to go.?

Christchurch virologist Lance Jennings says New Zealand is due for a more serious influenza season, as the past few have been mild.

The last serious season saw three children die from the disease during the influenza B epidemic of 2005.

Before that, an H3N2 strain of the influenza virus caused an epidemic in 1996 that saw patients waiting in corridors as hospitals couldn?t cope, Dr Jennings says.

This year?s influenza vaccine contains a Brisbane H3N2-like strain, an H1N1-like strain and a B strain.

The ?Brisbane strain? killed six children in Australia last year and medical authorities in Europe are warning it could be the most deadly influenza virus they have seen for 20 years, Ms Frost says.

Nearly all the dominant strains of the main influenza virus in the US this season, H1N1, show resistance to the leading antiviral drug oseltamivir (Tamiflu). H1N1 resistance to Tamiflu was first identified in New Zealand last year by Dr Jennings.

A variant of the H1N1 virus caused the 1918 influenza epidemic that killed an estimated 50 million people worldwide.

It is worrying these factors have come together at a time when influenza vaccination is a low priority for most New Zealanders because of the mild seasons recently, Ms Frost says.

Most New Zealanders still do not get the influenza vaccine, and just under half of those most vulnerable to developing serious complications do not get vaccinated.

Even healthcare professionals have poor uptake rates, Ms Frost says. DHB staff vaccination programmes only achieve coverage of between 20 and 40 per cent.

In the 13 years from 1980 to 1992, a total of 5650 New Zealanders died from influenza, at a rate of more than 400 a year.

The influenza vaccine is free for those at high risk ? people aged 65 and over and those with chronic conditions ? until the end of June. Traditionally, the number of influenze infections peaks in late June to July.
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Re: Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa
<hr style="color: rgb(204, 204, 204); background-color: rgb(204, 204, 204);" size="1"> <!-- / icon and title --> <!-- message --> The real "action" on swine H1N1 will be in the southern hemisphere in the next few months, and recombination with human H1N1 is a virtual certainty (and well into the "cause for concern" category).
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Re: Emergence and spread of oseltamivir-resistant A(H1N1) influenza viruses in Oceania, South East Asia and South Africa
<hr style="color: rgb(204, 204, 204); background-color: rgb(204, 204, 204);" size="1"> <!-- / icon and title --> <!-- message --> We would be in a deep mood indeed.

So this is now an pandemic wave 1 which would certainly introduct us in the 2nd wave after a half of year, or previously.

Only some vaccine which could target an main joint characteristic of both waves could shield us somehow.

The time of pandemic scheduling guessing speculations is finished, 4 years after the 2005.
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