Field evaluation on the effectiveness of a modified approach of chemical fogging against the conventional fogging in controlling dengue outbreak

A ? eld evaluation on the effectiveness of a modi? ed approach of chemical fogging of insecticides against the conventional method was carried out in the Seremban district within the state of Negeri Sembilan, Malaysia from 7th February 2003 to 7th September 2003. In the 3 months period, November 2002 to January 2003, prior to institution of modi? ed approach of chemical fogging, 27 of 42 (64.3%) dengue outbreaks were successfully controlled within the stipulated time frame of 14 days by the conventional approach of thermal chemical fogging. However, during the period when the modi? ed approach of chemical fogging was instituted, 25 of 27 (92.6%) dengue outbreaks within the same district were successfully controlled within the14-days time-line. Statistically, the modi?ed approach of chemical fogging signi? cantly improved the success rate of achieving dengue outbreak control within the stipulated time frame (?2 = 5.65, p = 0.01745). The modi? ed approach of chemical fogging also appeared to reduce the number of dengue cases recorded in the same district. This small pilot study shows that the modi? ed approach of chemical fogging reduced cost in carrying out each fogging activity to control dengue outbreak. It also substantially reduced the required time taken to complete each fogging activity in comparison to the conventional approach. Thus, it enabled similar number of workers to cover more localities simultaneously affected by the outbreaks. In addition, the modi? ed approach reduced the exposure time to hazardous insecticides for each worker doing hand-held thermal fogging