Prevalence in web infections

I’ve been very interested in applying epidemiology to the world of malware lately. Prevalence is quite simply the number of infected in a given population at a specific time. More specifically it is a ratio of infected over the number of people susceptible. When you look at the data we provide publicly we show you the number of infections for IP addresses and AS blocks. What we don’t show you however is the size of the networks that are infected.
This is something that is likely to change soon. I’m proposing that we start displaying the size of the network by summing up the total number of IP addresses under control of the AS derived from CIDR blocks. This would be fairly trivial for us to do but has some drawbacks. Firstly, CIDR blocks show the size of the network in terms of how many IP addresses are grouped together. It says nothing of how many web servers exist in that range or even how many of the IP addresses are active. This would be similar to saying there are 100,000 houses in zip code 02138 but not saying how many people live in those houses (if any at all). However I’m convinced that knowing the number of IP addresses under the control of an AS block is important.
For instance our page reporting on the top 50 AS block currently shows ThePlanet and Chinanet-Backbone in the number 1 and 2 positions. They have ~16,000 and ~15,000 respectively. However AS4134 (Chinanet) controls 70M IP addresses compared to only 1.5M for ThePlanet. The difference in those two numbers is staggering and it tells me that the number of infections sustained at ThePlanet is abnormally high.