Monday, 10 February 2014

H7N9 versus H5N1

Click on image to enlarge.
Data from the World Health Organization (2).
Green bars include surviving and fatal H5N1 laboratory-

confirmed cases in humans. The green "mountain" (area 
under the curve) is the accumulating tally of total cases. 
The red area-under-the-curve is the accumulating tally of  
fatal cases. The current total H7N9 cases is shown as a 
horizontal dashed blue line.
This is kind of a pointless exercise.

I admit it.

Every flu is different, just like every person is different and comparisons at the interface of the two is probably of little value beyond water-cooler conversation and blogging. But this is a blog. 

I've been wanting to visualize human case numbers for avian influenza A(H5N1) virus for a while. These numbers have been curated since 2003 when the World Health Organization started an official tally. To that chart I've added where the current total number of laboratory confirmed human cases of infection by avian influenza A(H7N9) virus sits on the accumulating case tally (the green area-under-the-curve line). This blue dashed line highlights what we've heard before; H7N9 cases are piling up faster than H5N1 cases did. 

From 2003 it took 4-years to reach the 330'ish human H5N1 case mark; it took H7N9 51 weeks.

H5N1 was first noted in humans in 1997, and there were at least 18 other cases between then and 2003 (1). That is in the early days of PCR methods and the early days for global communication of things like "hey everyone, I have this bird-killing, human-killing virus breaking out in my back yard". 


References..

  1. H5N1 in humans
    http://www.nejm.org/doi/full/10.1056/NEJMra052211
  2. WHO H5N1 data
    http://www.who.int/influenza/human_animal_interface/EN_GIP_20140124CumulativeNumberH5N1cases.pdf