Just for yonks, I grabbed the WHO confirmed Avian Flu cases list and did a little plot of cumulative cases vs time…
The blue curve is cumulative cases; the red curve is cumulative deaths.
The date is the approximate date of WHO report, with 28 Jan 2004 as the zero date (11 cases, 8 deaths). The dates are approximate because I just counted months between the slightly uneven spaced report dates and assigned 30 days per month. Since the data is coarse grained this should not matter over this length time span.
If you fit it with an exponential, the doubling time is just about one year.
If I were feeling energetic I’d fiddle with a proper log-lin fit and see if it is trending to saturation (logistic growth) or faster-than-exponential.
But, to be honest, the data are too scrappy and selection biased (early cases probably overlooked and fraction of deaths overreported) for that to be a useful exercise, yet.
Jan 2007 will be interesting.