The spatial-temporal distribution of dengue cases in relation to peridomestic mosquito vectors, Commonwealth of Dominica

The Commonwealth of Dominica has experienced a major increase in dengue activity in recent years. Because of the lack of an available vaccine or long-term sustainable method for vector control, establishment of an active dengue surveillance system is necessary to effectively implement existing disease prevention efforts. The surveillance system in Dominica could be significantly improved through a better understanding of the spatial-temporal distribution of dengue in relation to the mosquito vector. Therefore, the objectives of this study focused on understanding the spatial-temporal epidemiology of recent dengue cases in Dominica, conducting an ovitrap survey of the households containing dengue cases, and identifying practical statistical techniques that can formalize procedures for an improved surveillance system Ministry of Health and Environmental Health officials can use. Dengue data was collected from the Health Information Unit division in the Ministry of Health. A total of 86 laboratory confirmed dengue cases occurring from January 2007-August 2010 were used in the study. Necessary statistical techniques identified for a surveillance system included kernel density estimation, Mantel-Haenszel test, and the Knox index. CrimeStat was identified as user-friendly open source software that can be effective in resource limited settings. Results revealed space-time clustering of dengue cases occurring from January 2007-August 2010, with a significant majority of dengue cases located at households in regions of high urban density and high Aedes aegypti density. This project identified several areas of improvement which include: establishment of a dengue surveillance system utilizing proposed statistical techniques, a complete mosquito survey of the entire island that quantifies the threshold of mosquito density that would lead to an epidemic, and targeted mosquito control efforts that incorporate a greater dispersal range of Aedes aegypti.