Friday 25 October 2013

Influenza A(H7N9) in Zhejiang, Dutch DURC and dogs..

With the second H7N9 case (see FluTracker's thread) in Zhejiang, located only 13km from the earlier case, things seem to be picking up where they left off in late April. Poultry exposure seems key to this latest case who was a farmer who engaged in poultry trading. That word, trading, also sparks concern. It suggests that the farmer was exposed to poultry coming from, or going to, somewhere else. H7N9 is on the move. Both patients are very unwell.

Zhejiang province had the steepest rate of case acquisition back then and reached the highest H7N9-confirmed case number as well. 

Looks like this province is going to be a key battleground for the next wave of H7N9.

Meanwhile, Eurosurveillance continues its fantastic coverage of this and the Middle East respiratory coronavirus  and H7N9 outbreaks. It already has a paper online (less than a week turnaround) of the earlier Zhejiang H7N9 case in a 35-year old male (35M) which includes a note about the subsequent Zhejiang case! Outstanding work to the researchers and the publishing team. Quality publication almost in the time it takes to write blog post!

This journal certainly highlights how quickly detail research results and analysis, when submitted to peer review, can be published. 

Click to enlarge. The laboratory turnaround
times for H7N9 detection (where suitable date
data exist) since the outbreak began in early 2013. 
  • 35M was identified though the surveillance system for unexplained pneumonia
  • He was not a farmer and had not had close contact with another probable case. The laboratory turnaround times on this case was 7-days. A 2.2 day improvement on the rolling average I stopped calculating May 6th.
  • The most likely source of exposures was a trip to rural region of  Ningbo city where he may have been in contact with animals. But that was 10-days prior to onset which would make it a long incubation period. 35M remains unconscious so further detailed tracking of exposures is not possible
  • The virus was >95.5% identical to H7N9 from earlier in the year but with 5 hitherto unreported mutations in the neuraminidase (NA) gene. 2/9 bird market samples were also H7N9 PCR-positive but could not be sequenced due to low viral load
Meanwhile, Reuters reports on Albert Osterhaus and Ron Fouchier at the Erasmus Medical Center who are firing up the "gain-of-function" studies to look at what would be required for H7N9 to become a pandemic virus; essentially changing the virus to look for increased transmission. This work will be performed in an highly secure, enhanced biosafety Level 3 lab. Which of course doesn't change the subject matter - but does define how difficult it would be for that to escape. It's not convincingly clear why this virus needs to be given an evolutionary push, rather than "reverse-engineering" those influenza viruses that have previously been pandemic viruses - or some other approach with less risk of creating a virus that if it escaped, would cause a pandemic. Well, to me at least...but I'm no flu expert. You can find much more on dual-use research of concern (DURC) in Laurie Garrett's latest writing over at Foreign Affairs.

And to add to general influenza virus concerns, Sun and colleagues report in Infection, Genetics and Evolution, that infectious H9N2 (isolated using embryonated chicken eggs), strains of which has been implicated in providing genetic material to H7N9, can be isolated from dogs. The isolate was called A/Canine/Guangxi/1/2011 (H9N2). Between 20% 45% of dogs were found to be antibody-positive to H9N2. A range of dogs seem to have been virus-positive with signs and symptoms including loss of appetitie, cough, sneeze, nasal discharge and raised temperture. Some were asymptomatic. Cats next please?

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