Dengue fever is a serious mosquito borne disease which every year kills a number of people in Chiang Mai while making thousands ill and 2013 has turned out to be a record year for infections.
The rainy season has seen widespread spraying by fogging machines of insecticide apparently to no avail. Also there has been a public relations campaign, but was its purpose to put the mayor in a good light or to address the health challenge?
My parents taught me that malaria was brought under control by destroying the mosquito breeding habitat with spraying of stagnant pools with kerosene.
However in the Chiang Mai Railway park, where every day at dusk, when mosquitoes are most active, joggers plod around the swimming pool ( the second picture in this link) which hold about 30 centimetres of clean rain water. And in the pool grow algae and mosquitoes as this photo taken on October 8th shows.