Tachiiri Kaoru, Klinkenberg Brian, Mak Sunny, Kazmi Jamil
Department of Geography, University of British Columbia, Vancouver, BC, Canada.
Int J Health Geogr. 2006 May 16;5:21. doi: 10.1186/1476-072X-5-21.
West Nile virus (WNv) has recently emerged as a health threat to the North American population. After the initial disease outbreak in New York City in 1999, WNv has spread widely and quickly across North America to every contiguous American state and Canadian province, with the exceptions of British Columbia (BC), Prince Edward Island and Newfoundland. In this study we develop models of mosquito population dynamics for Culex tarsalis and C. pipiens, and create a spatial risk assessment of WNv prior to its arrival in BC by creating a raster-based mosquito abundance model using basic geographic and temperature data. Among the parameters included in the model are spatial factors determined from the locations of BC Centre for Disease Control mosquito traps (e.g., distance of the trap from the closest wetland or lake), while other parameters were obtained from the literature. Factors not considered in the current assessment but which could influence the results are also discussed.
Since the model performs much better for C. tarsalis than for C. pipiens, the risk assessment is carried out using the output of C. tarsalis model. The result of the spatially-explicit mosquito abundance model indicates that the Okanagan Valley, the Thompson Region, Greater Vancouver, the Fraser Valley and southeastern Vancouver Island have the highest potential abundance of the mosquitoes. After including human population data, Greater Vancouver, due to its high population density, increases in significance relative to the other areas.
Creating a raster-based mosquito abundance map enabled us to quantitatively evaluate WNv risk throughout BC and to identify the areas of greatest potential risk, prior to WNv introduction. In producing the map important gaps in our knowledge related to mosquito ecology in BC were identified, as well, it became evident that increased efforts in bird and mosquito surveillance are required if more accurate models and maps are to be produced. Access to real time climatic data is the key for developing a real time early warning system for forecasting vector borne disease outbreaks, while including social factors is important when producing a detailed assessment in urban areas.
西尼罗河病毒（WNv）最近已成为对北美人群的健康威胁。1999年在纽约市首次爆发疫情后，WNv已广泛迅速地传播到北美各地，除了不列颠哥伦比亚省（BC）、爱德华王子岛和纽芬兰外，已蔓延至美国的每一个毗邻州和加拿大的每一个省份。在本研究中，我们建立了致倦库蚊和尖音库蚊的蚊虫种群动态模型，并通过利用基本地理和温度数据创建基于栅格的蚊虫丰度模型，在WNv抵达BC省之前对其进行空间风险评估。模型中包含的参数有根据BC疾病控制中心蚊虫诱捕器位置确定的空间因素（例如，诱捕器到最近湿地或湖泊的距离），而其他参数则从文献中获取。还讨论了当前评估中未考虑但可能影响结果的因素。
由于该模型对致倦库蚊的表现比对尖音库蚊好得多，因此使用致倦库蚊模型的输出进行风险评估。空间明确的蚊虫丰度模型结果表明，奥肯那根山谷、汤普森地区、大温哥华地区、弗雷泽山谷和温哥华岛东南部的蚊虫潜在丰度最高。纳入人口数据后，由于人口密度高，大温哥华地区相对于其他地区的重要性增加。
创建基于栅格的蚊虫丰度地图使我们能够在WNv引入之前，对整个BC省的WNv风险进行定量评估，并确定潜在风险最大的区域。在制作地图的过程中，我们还发现了与BC省蚊虫生态学相关的知识中的重要空白，而且很明显，如果要制作更准确的模型和地图，就需要加大鸟类和蚊虫监测力度。获取实时气候数据是开发预测病媒传播疾病爆发的实时预警系统的关键，而在城市地区进行详细评估时纳入社会因素很重要。
