The use of fine nets to prevent the breeding of mosquitoes on dry farmland in southern Taiwan

Objectives: The stagnate water stored in buckets traditionally used by farmers in southern Taiwan to irrigate their dry farmland, serves as favorable breeding ground for Aedes aegypti, the vector of the dengue virus. The public health bureau there distributed fine nets to the farmers to cover their buckets to reduce vector breeding sites. The goal of this study was to compare the container index (CI) in Alian and Tianliao Townships, Kaohsiung County in southern Taiwan over a 2-year period, for 1 year before the fine nets were distributed and 1 year after. Methods: In March 2005, we selected eight villages in Alian Township and 10 in Tianliao Township. Specialists monitored the local Stegomyia indices every month. We compared the 2005 CI to the 2004 CI, representing the years before and after the nets were used. The results of the comparisons were analyzed by paired t-test and Wilcoxon rank test. Results: In Alian Township, mean CI had significantly reduced to 1.63 levels (May 2005) from a mean 5.88 level in May 2004 (paired t-test, p = 0.001 and Wilcoxon rank signed test, p = 0.0012). In Tianliao Township, CI was reduced to 1.2 from 2.3 in May 2004 (p<0.0001 and p=0.007, paired t-test and Wilcoxon rank signed test, respectively). Conclusions: The nets effectively reduced the CIs in these townships, and might be considered for wide scale use. The mosquito nets were generally welcome by the farmers who found them to be convenient, inexpensive and practical. (c) 2009 Elsevier B.V. All rights reserved.