Friday 31 January 2014

H7N9 snapdate: cases in 2013 vs 2014...[UPDATED]

Since I started tracking this beastie (the same time I started this blog) in April 2013, I've tended to use weekly data - because more is more!

This one presents the data by month and it really highlights that - at least to date - human infections with H7N9 have been focused on a single month. 

That's not really a seasonal thing (although it is a colder month) - just opportunistic - to my mind anyway. An opportunity last year that seemed to have been lost to H7N9 by market closures, cessation of the movement of its host and the encroaching warmer weather. 

With markets now closed in Zhejiang and Shanghai, we should see some impact taking effect once a 2-week period has passed, which is 2-weeks from the 24-Jan. 

Click on image to enlarge.
Plotted by week of disease onset or date
reported if onset data unavailable. Keep in
mind that, on average (n=199/273 data points)
there are around 9-days between illness
onset and case announcement.
Today signals the end of the 1st week; 7-Feb the second week. At the very least, Zhejiang-acquired cases should wither by the end of that period & hopefully an effect will be visible leading up to it. It may still take another week to 10-days to see that trickle through the reporting system (see figure legend). Last night we saw 4 new cases announced from Zhejiang province. Fewer than some weeks, more than others.

So Zhejiang is our sentinel for an impact from market closures. The place to keep an eye on in the coming weeks as an indicator of H7N9 activity in the region. Or it might just all be down to warmer weather shooing the H7N9 away! But at least we have last year as a guide of what to expect this year. If you can expect anything from influenza.

And just to add, there are also cases acquired in areas with active markets and those acquired at rural farms etc during the mega-travel period that is the Chinese spring festival....weeell, let's  just observe and see how those chickens fall as they do.

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