Friday 17 January 2014

H7N9 hasn't left, it's just been building capacity... [UPDATED WITH NEW WHO DON]

Click on image to enlarge.
I updated this chart a week ago, when the avian influenza A(H7N9) virus tally was at 158.

This morning I check FluTrackers list and its sitting at 189 cases; 31 reported so far this week. Just to be clear though, not all of those cases acquired their infection in this week. Some cases go back to mid-December 2013. 

This week has so far seen 10 cases with disease onset listed as occurring in it (5, 17 and 6 in going back by week in time). For comparison, at the height of the 2013 H7N9 outbreak, in Weeks 6-9 (March and April) there were 17, 29, 40 and 19 cases in each of those weeks respectively. We don't seem that far off from those numbers right now - except that this outbreak/wave we're seeing cases starting from more regions than last time. Without some serious intervention, I think 2013's peak of 40 case acquisitions in a week will seem small in 2014.

We can also see from the chart that Fujian province is emerging from the background noise of a handful of cases and could be starting that steep'ish climb that suggests bird-to-human transmission events are on the rise. That adds to ye other "newcomer", Guangdong province. In 2013 Shanghai, Zhejiang and Jiangsu were the hotzones, and they have all reported cases in recent weeks. H7N9 hasn't left, it just built more capacity to transmit...because that is a virus's life.

Which brings me to a whinge. 

You could be forgiven for thinking that from all we've learned about H7N9 and all that we already knew about influenza viruses and markets and transmission and detection and diagnosis and treatment) from...
  • The 318+ research papers
  • The many words written in a vastly greater number of news articles, blogs and comments
  • The many (I expect) millions of dollars invested in learning, battling and cleaning up after H7N9 over the past 48 weeks
  • The strong link between a precipitous drop in new cases and the closure of live poultry markets in 2013 
..that a similar response to the liver bird markets would have been triggered this time around. In 2013 the first key market closures were underway by Week 8 (1st week of April'ish) after the first known H7N9 case became ill (Feb-18). This time around we're already at 15-weeks after H7N9 cases started to accrue again (taking the start as the week beginning 7-Oct).

I forgive you for thinking this way because I think that way too. This much newly and recently accrued knowledge should have informed the decision to close markets by now. Or change the markets. I get that fresh poultry is an ingrained and cultural issue. But I also get that public health is at serious risk just now, not just in south east China but globally. Is it worth your life or the life of a family member just to get a clucking chicken from a market rather than a farmed pre-prepared one? The solution to reduce that risk to people and the world lies in the live bird trade and associated habits. Closing down a market here and there for "sanitation" (or aerosolising everything by hosing it out as @Laurie_Garrett suggested in a fantastic Twitter exchange earlier today), doesn't appear, to the casual observer, to be slowing infections. Can a "market" really be suitably sanitized? Not just the one-off cleanup, but the more conceptual idea of a market as a large gathering of animals frequented by hundreds of thousands of people each day, meeting there, handling, haggling, buying, breathing, drinking, eating... 

Can you ever get ahead of that risk while markets exist in their current form?

Laurie Garrett also mentioned a practice involving the sniffing of a chicken's butt to see if it is healthy. Beyond the laughter that image triggers, flu is a gastro virus in birds. Better cleaning of a market's environs won't stop that practice, nor other risky practices, from being  a source for influenza virus acquisition.

Perhaps sanitizing markets is working. Perhaps we'd be seeing a lot more cases if such cleansing had not been happening. But aren't the markets just being restocked with HXNY-laden birds the next day or week?

The H7N9 cycle wasn't broken when the markets were shut in 2013; it was just temporarily halted. 

We know that these birds have multiple influenza viruses in them including H9N2, H5N1 and H7N9. 

The conditions for the emergence of viruses we already know, and those we have yet to meet, continue to be created and maintained. 

The spectre of "the next pandemic" will not get the banishment it deserves while the live bird market system continues as it has. It's just our luck that may run out as it did for those infected by H7N9.

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