A new pandemic

It is not impossible that we could that threat shift - from H5N1 to H5N5, or H5N6, or to some other n-type, in the months or years ahead.  The H5Nx virus has an large - and growing - array of diverse hosts to inhabit, and no lack of genetic diversity on which to draw. 

While the world remains focused on two relatively new H5N1 genotypes (B3.13 & D1.1) circulating in North America, there are literally hundreds of other genotypes of H5Nx evolving and adapting - mostly out of our view - around the globe.

At the same time, there are hundreds of other influenza subtypes - many also with zoonotic potential - evolving and reassorting at a furious rate.  The CDC's IRAT list only lists 25, but it is far from complete. 

While any of them could suddenly assume the poll position in the race to the next pandemic, the H5N6 virus - circulating in China since early 2014 - is one that we watch with considerable interest. 

Of 92 human infections reported so far by China, about half have died

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All of which brings us to a new report, published this week in Transboundary & Emerging Diseases, which describes two new genotypes of H5N6 recently isolated in China, with one carrying the internal genes from LPAI H9N2 demonstrating worrisome signs of mammalian adaptation. 

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Just three weeks ago, in China CDC Weekly: Infection Tracing and Virus Genomic Analysis of Two Cases of Human Infection with Avian Influenza A(H5N6) — Fujian Province, China, we looked at a report that stated:

(H5N6) " . . .  has acquired mutations that may enhance human receptor binding affinity, viral replication capacity, pathogenicity, and neuraminidase inhibitor resistance."

None of this guarantees that H5N6 will become the next big pandemic threat.  But it should remind us that even if we somehow manage to subdue H5N1, any victory will be short-lived. 

Because there are plenty of other novel viruses with zoonotic potential in the queue.