I agree 5miles, there will always be those who insist on recycling their colds/germs and whatever else through the air con systems, these people take great pride in saying 'I've had no sick leave for 10 years,' - Sick leave no, Sick/ill - yes!
Thinking about what Jerricho said, instead of carrying over sick leave year in year out with no real benefit to those who don't use it, how about as an incentive to those who perhaps abuse the system, extra leave for an acceptable above average attendance record which could then be commuted annually or saved and put towards going early. Browsing the internet, it seems that many companies are begining to tackle the 'thorny/taboo/don't go there' issue of poor attendance and how that effects the rest of the workforce.
It would be interesting to get a union take on this!!