Avian Flu Diary: Referral: VDU On Recent Uptick In H7N9 Activity

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After a decade where the H5N1 virus reigned supreme in the avian flu world, a little less than two years ago a new virus emerged in Eastern China, called H7N9. A reassortant between the ubiquitous, but low path H9N2 poultry virus and a couple of (as yet) unidentified bird flu viruses (see Evolution Of H9N2 And It’s Effect On The Genesis Of H7N9) this new viral brew produces no symptoms in birds, but in humans produces significant morbidity and mortality.

As the chart above shows, we’ve seen two human waves of the virus - both beginning in mid-winter – and there are signs that a third wave may be beginning to surface.

While the numbers remain small, there has been a decided uptick in case reports out of China in the past few weeks. There are, of course, questions over just how well surveillance and reporting are picking up on these cases since they come at the same time as China’s seasonal flu season ramps up.

As we’ve discussed often - and it doesn’t matter where, or what disease - not every infection will be detected. And depending on the spectrum of symptoms (asymptomatic or mild – up to severe), the percentage picked up by surveillance can often be the tip of the iceberg – or in the case of the CDC graphic below – of the pyramid (see When No Number Is Right).

While the official count remains under 500 cases, there are some researchers who put the real number of symptomatic H7N9 cases in the tens of thousands (see Clinical severity of human infections with avian influenza A(H7N9) virus, China, 2013/14).

Nobody knows of course, and so we must deal with the numbers we have.

Which is something Dr. Ian Mackay does exceedingly well, producing (along with astute commentary) some of the best Avian Flu, MERS, and Ebola graphics on the web on his Virology Down Under blog. Today he starts off the new year with a `snapdate’ on China’s H7N9 activity. Follow the link below to read:

Saturday, 3 January 2015

H7N9 outbreak #3 underway?

What better way to start 2015 than a snapdate!! For those who are new to them here on VDU, they were initiated here and defined here as snap updates - posts that don't have lots of detail and chat...although they almost always end up having lots of chat!

This one is an update of the situation of one of the many avian influenza viruses ("bird flus" if you must) around again - avian influenza A(H7N9) virus, or just 'H7N9'.

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