Household practices of temephos use for dengue larval control, Khon Kaen province, north-east Thailand

In the absence of a vaccine against dengue infection, laryal control remains the only option for the control of Aeries aegypti, the vector species. Temephos, a larvicide, has been the main agent for the control of the larvae of dengue vectors in Thailand since the 1970s. The use of temephos not only requires estimation of the correct doses to be added to water containers but also retreatrnent at regular intervals. The present study investigated the application of temephos in households in both rural and urban areas of Khon Kaen province, Thailand. The study covered 966 households and 5821 water storage containers. The results showed that temephos was commonly added to non-potable water and the percentage of rural households using temephos was more than twice as high as that in urban settings (rural 60%; urban 25%). The constraints identified in the usage of temephos included insufficient availability of temephos, inappropriate methods of application and no retreatment at regular intervals. In urban areas, the standard packages available facilitated the correct use of temephos in dragon jars used for storage of water for drinking purposes (60 to 200 litres). However, temephos promotion also suggested application of the chemical primarily to containers of bathing water, which are rectangular cement containers with a much greater volume (>500 litres). On the basis of these results, the study suggests the need to look beyond just the issue of distribution of temephos, but also focus attention on promoting the appropriate dose application of temephos.