Wednesday, 15 January 2014

H7N9 cases: trekking to the next peak

Click on image to enlarge.
I have switched this chart to depict the case number per 
week using a line rather than bars. While not technically accurate,
 it is just more clear than a bar format as the dataset grows. 
Please be aware that the dots on the line are the actual 
data points.  The connecting lines are just for show. The red bar
above the "mountain peak" is a 7-day lag time - see below
for description.
We can see from this chart that the next H7N9 wave is well underway. 

There has been a distinct upward trend in new confirmed case announcements since about October 2013. 

Despite what looks like a slow-down at the top of that peak (the pale blue mountain), remember that there is a lag between a patient getting sick and when that patient is announced to the public as a laboratory-confirmed H7N9 case. How long is that lag though?

Click on image to enlarge.
As I did in 2013, I've plotted this lag as the time taken between date of confirmation (or date the case was reported publicly) against the week that case became ill. The data gaps represent times when there were no H7N9 confirmed/reported cases. The lag is currently sitting at approximately a week (6-8-days). So think of the slowing at the top of the peak in the earlier chart as more of a "guide" to what to may be coming rather than a true indication of now. 

I'm bet that slope will continue as we plug in today's and tomorrows and the next day's new cases; right up until we get a precipitous decline when the live poultry markets finally get shutdown in the face of overwhelming concern about case numbers and deaths. 

It's all well and good to prefer seeing a healthy chicken before purchasing it, but what about ensuring a healthy family afterwards?