Friday, December 01, 2017

Cell Research: H7N9 Viruses - A Rare Second Warning

Credit FAO - Nov 2017


Although all appears quiet on the H7N9 front right now, that happy state of affairs is not expected to last much longer as winter sets in across China. Last year's surprising surge in cases and the emergence of new strains - after two years of decline - has understandably raised the level of concern about this virus around the globe.

Over the past couple of months the research floodgates have opened, and we've seen:
EID Journal: Human Clusters Of H7N9 In China, 2013 - 2017
Cell Host & Microbe: HPAI H7N9 Lethality & Transmission In Ferrets
Cell Research: Another Cautionary H7N9 Study Out Of China
J. Virology: Emergence & Adaptation Of HPAI H7N9 In Birds and Humans
EID Journal: H7N9 Viruses Co-circulating In Chickens In Southern China, 2016–2017
These studies suggest that HPAI H7N9 has acquired important mammalian adaptations - and while sustained or efficient human-to-human transmission has not been observed - it is feared they may increase both its virulence, and its transmissibility, and together they could  enhance its pandemic potential.
The challenge - particularly after 15 years of watching H5N1 spread globally yet fail to spark a pandemic - is talking about these changes without sounding alarmist or inuring the public to such warnings to the point they no longer care.
Influenza viruses - particularly novel flus - have a habit of zigging when we expect them to zag.  Just when we think we've got them figured out, they prove to us how little we really know.
The ecology of influenza around the globe - in humans, birds, swine and in other mammals - is an extremely complex and constantly changing system. Add in the randomness of viral evolution - and any predictions must be taken with a large grain of salt.
Despite this immense margin for error - given the disastrous downsides of being blindsided by a severe pandemic - we can scarcely afford to ignore the warning signs and simply hope for the best.
To that end we've a Research Highlight published today in Cell Research that reviews the recent changes observed in the H7N9 viruses circulating in China, and cautions that we've received a rare second warning with this virus - one which we should take seriously. 
I've only included a snippet from the article, so follow the link to read it in its entirety.

Avian influenza H7N9 viruses: a rare second warning
Kanta Subbarao

Cell Research

Published online:01 December 2017
Avian influenza A H7N9 viruses that emerged in China in 2013 have reappeared each year, causing more than 1 600 severe human infections. As these viruses have evolved in nature, they have gained some and can gain additional virulence determinants that enhance their risk for humans, underlining the urgent need to control and eradicate H7N9 viruses in China.
Once is a warning, twice is a lesson; we cannot afford to ignore the spread of H7N9 viruses and allow them to become enzootic. As the authors state5, focusing control measures only on HPAI-infected flocks will not solve the problem because HPAI viruses are derived from LPAI viruses. Both LPAI and HPAI H7N9 viruses must be eradicated from avian species and human isolates of H7N9 viruses must be monitored closely.
        (Continue . . . .)

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