Emergency vector control in a DENV-2 outbreak in 2002 in Pingtung City, Pingtung County, Taiwan

This paper reports the strategy and effectiveness of an emergency control program conducted in Pingtung City, Taiwan in response to dengue outbreaks. In our control strategy, we carried out 3 insecticide space sprays with an interval of 6-7 days and 2 source reductions to cover the entire duration of dengue virus exposure in humans and mosquito vectors. The control effect was demonstrated by a significant reduction in the Breteau (51.1%) and larval (80.0%) indices, but no such effect was demonstrated by alterations in the adult index (54.9%), house index (45.0%), container index (33.8%), or by indoor (15.8%), outdoor (31.2%), or total water-filled containers (22.7%) per 100 premises examined. The contribution made by the reduction in the number of positive containers was primarily in the outdoor (77.2%), and not the indoor containers (-6.0%). This reduction attributed to an overall reduction of 96.0% Aedes albopictus larvae and 71.0% Aedes aegypti. Therefore, 4 weeks after this extensive emergency control measure, the number of dengue cases dropped to one. Finally, due to both the decrease in temperature resulting from the upcoming winter, and to the sustained effort toward source reduction, the transmission cycle of DENV-2 in Pingtung City was interrupted at the beginning of 2003, and no additional cases were identified in late 2003.