Tuesday, February 28, 2017

Taiwan Reports Imported H7N9 Patient Has Died


A little over 3 weeks ago, in Taiwan CDC Announces An Imported H7N9 Case, we learned of a 69 year old businessman who fell ill while visiting Guangdong Province in late January.  After first seeking medical attention on the Mainland, he returned to Taiwan where he was hospitalized, and eventually (on Feb. 4th) was diagnosed with H7N9.
This story took a major twist  8 days ago when it was revealed this patient - who was in critical condition - carried a similar HPAI mutation to the one announced discovered in two Guangdong patients 9 days ago (see WHO Report).

All three known cases of HPAI H7N9 infection are also reported as having genetic changes associated with neuraminidase inhibitor antiviral drug resistance.

There appears to be some question over whether these viruses carried these changes when they were acquired - or if these patients developed resistance after receiving antiviral treatment (aka a `spontaneous mutation').  

Of these three patients, the first (a 43-year-old woman who fell ill in late December) has recovered, the second (a 57-year-old male who fell ill in early January) remains in critical condition, and the third we learn, died overnight. 

First the media report, then I'll return with a bit more.

Taiwanese man dies of H7N9 avian flu

2017/02/28 15:23:01
Taipei, Feb. 28 (CNA) A 69-year-old man who contracted the H7N9 avian flu virus in China last month has died, becoming the first Taiwanese victim of that virus strain, the Centers for Disease Control (CDC) said Tuesday.

The businessman died late Monday, said Lo Yi-chun (羅一鈞), deputy director-general of the CDC. The patient had been in hospital in Kaohsiung for 27 days after falling ill in China and returning to Taiwan on Jan. 25 to seek medical help.

(Continue . . . )

A mutated H7N9 virus displaying signs of antiviral resistance is obviously a serious concern.  But we are still dealing with a fairly small sample size (n=3) out of 52 cases reported this year from Guangdong Province.  The first two patients were infected roughly 60 days ago, and the third in mid to late January, and China has not announced any more recent cases.

While there may well be more cases like these, China will have to disclose a lot more surveillance data (human & poultry) before we can know if this new strain has `legs'.  

And while worrisome, these are far from the first antiviral resistant H7N9 strains we've seen.

A small number of oseltamivir (Tamiflu ®) resistant strains were detected during the first wave in 2013 (see The Lancet: Antiviral Resistance In Two H7N9 Patients), including Taiwan's very first imported case (see The Taiwan H7N9 Patient & Antiviral Resistance), who developed resistance while receiving treatment. 

For a more detailed look at the mechanisms and drivers of antiviral resistance you may wish to revisit mBio: Antiviral Resistance In H7N9.

Whether this particular HPAI H7N9 stain is biologically `fit' enough to compete with all the other wild types in circulation - or turns out to be an evolutionary flash in the pan - remains to be seen.

But successful or not, with literally dozens of genotypes already in circulation - and their continual intermixing with other influenza A viruses - this won't be the last time we see this virus reinvent itself. 

While most of these incarnations will carry no significant evolutionary advantage, it only has to get it `right' once for us to find ourselves facing another global public health crisis.

No comments: