Coverage-Dependent Effect of Insecticide-Treated Curtains for Dengue Control in Thailand |
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| Authors: | Veerle Vanlerberghe Yuwadee Trongtokit Somchai Jirarojwatana Ravisara Jirarojwatana Audrey Lenhart Chamnarn Apiwathnasorn Philip J. McCall Patrick Van der Stuyft |
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| Affiliation: | Unit of General Epidemiology and Disease Control, Institute of Tropical Medicine, Antwerp, Belgium; Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Regional Office of Disease Prevention and Control (Region 3), Chon Buri, Thailand; Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Department of Public Health, Ghent University, Ghent, Belgium |
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| Abstract: | Evidence on the effectiveness of insecticide-treated curtains (ITCs) for reducing densities of Aedes mosquitoes, the principal vectors of dengue, is scarce. In Laem Chabang southeast of Bangkok, Thailand, the Breteau Index (BI) (number of positive containers/100 houses) was 45 in October 2006. In March 2007, we distributed long-lasting ITCs in 22 clusters (2,032 houses) and selected 66 control clusters (661 houses). Routine control activities continued in all clusters. Six months after distribution, the BI was 25.8 and 77.6 in intervention and control areas, respectively (P < 0.001). Eighteen months after distribution, the BI was 21.8 and 23.8, respectively (P = 0.28). The average number of ITCs/house at cluster level was associated with the BI (P < 0.01) after six months, when 70.5% of households still used ITCs, but not at 18 months, when ITC coverage had decreased to 33.2%. Deployment of ITCs can result in considerable reductions in Aedes infestation levels, but the effect is coverage dependent. |
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