First off the bat (and this should be obvious): it's not enough to point to global trends as an explanation for last year's outbreak. Those trends would explain a nationwide, or scattered rise in dengue, but they cannot be invoked to explain why the outbreak clustered so intensely in a single city (Tainan) and in several areas of the city in particular.
Second, the Li Chang system has its' limitations and should in many respects be regarded as a largely redundant cultural curiosity (e.g. if the city government website was half-decent, which it is not, why would we need to rely on our Li Chang for information from the city government?).
Third, some real-life observations...
(a) Last summer when the outbreak began, the park behind my house would fill up with rain. Probably because the soil is shallow, the park would accumulate large areas of standing water which should have been drained as soon as possible. In actual fact, it took the city government two or three weeks to send a couple of blokes out with a diesel generator and a hose pipe to get it done. That wasted time may have meant wasted lives.
(b) For years now there has been a persistent problem of fly-tipping in the local parks. I am not talking about mattresses and furniture and the like. I am talking about food and other household waste. What happens is a number of local people miss the garbage truck (perhaps because they don't work 9-5 hours), and instead of asking a friend, or neighbour, or a Lin Chang for help (or bagging the garbage and keeping it the garage until the next time the truck comes - like I do), they just dump it in the local park. Because the park is cleaned by a single warden with a few formal volunteers (and myself - out of necessity), this garbage is dumped at night and is not picked up and removed until late the next morning, often just before noon. "Wet" garbage like this is an obvious breeding ground for mosquitoes and also happens to attract rats and the possible diseases they bring with them. This is a persistent problem for years in both public parks I use here in North District and I have complained endlessly about it and nothing is ever done. And not for the want of suggestions, either. The mayor of Tainan is either unaware of the problem, doesn't regard it as important, finds it politically inconvenient to allocate proper funding to solve the problem, or is too busy acting the champagne socialist up in Taipei.
(c) Although a great effort was made to spray private homes with mild insecticide, this was a somewhat unpopular and often farcical policy that inconvenienced thousands of us, myself included (i.e. I had to take an afternoon off work to look after my dogs while the house was sprayed). From the beginning of the outbreak I began to spend a small fortune on insect repellents and a new washing machine and going through the house cleaning up to make sure it was as mosquito proof as could be. I still had my house sprayed, and lost half a day's worth of earnings which was of course not reimbursed. Other people were forced out of their homes, which they had carefully cleaned and proofed, only to be bitten by mosquitoes whilst waiting around on the streets outside while their homes were being sprayed.
To sum up, we need to find a convincing set of explanations as to why the outbreak clustered so intensely in Tainan city and if that requires taking a critical look at the policies of our celebrated mayor, then so be it. Waffling on about global warming and how the Li Chang "straddle the line between society and the state" is just the sort of thing one would expect from academics on the public purse.