Department of Geography, New Mexico State University, Las Cruces, NM, USA.
Department of Biology, New Mexico State University, Las Cruces, NM, USA.
Parasit Vectors. 2018 Apr 19;11(1):255. doi: 10.1186/s13071-018-2832-6.
Chikungunya virus (CHIKV) originated in a sylvatic cycle of transmission between non-human animal hosts and vector mosquitoes in the forests of Africa. Subsequently the virus jumped out of this ancestral cycle into a human-endemic transmission cycle vectored by anthropophilic mosquitoes. Sylvatic CHIKV cycles persist in Africa and continue to spill over into humans, creating the potential for new CHIKV strains to enter human-endemic transmission. To mitigate such spillover, it is first necessary to delineate the distributions of the sylvatic mosquito vectors of CHIKV, to identify the environmental factors that shape these distributions, and to determine the association of mosquito presence with key drivers of virus spillover, including mosquito and CHIKV abundance. We therefore modeled the distribution of seven CHIKV mosquito vectors over two sequential rainy seasons in Kédougou, Senegal using Maxent.
Mosquito data were collected in fifty sites distributed in five land cover classes across the study area. Environmental data representing land cover, topographic, and climatic factors were included in the models. Models were compared and evaluated using area under the receiver operating characteristic curve (AUROC) statistics. The correlation of model outputs with abundance of individual mosquito species as well as CHIKV-positive mosquito pools was tested.
Fourteen models were produced and evaluated; the environmental variables most strongly associated with mosquito distributions were distance to large patches of forest, landscape patch size, rainfall, and the normalized difference vegetation index (NDVI). Seven models were positively correlated with mosquito abundance and one (Aedes taylori) was consistently, positively correlated with CHIKV-positive mosquito pools. Eight models predicted high relative occurrence rates of mosquitoes near the villages of Tenkoto and Ngary, the areas with the highest frequency of CHIKV-positive mosquito pools.
Of the environmental factors considered here, landscape fragmentation and configuration had the strongest influence on mosquito distributions. Of the mosquito species modeled, the distribution of Ae. taylori correlated most strongly with abundance of CHIKV, suggesting that presence of this species will be a useful predictor of sylvatic CHIKV presence.
基孔肯雅病毒（CHIKV）起源于非人类动物宿主与森林中媒介蚊子之间的丛林传播循环。随后，该病毒跳出了这个祖先循环，进入了由嗜人蚊子传播的人类地方性传播循环。丛林 CHIKV 循环在非洲持续存在，并继续溢出到人类中，为新的 CHIKV 菌株进入人类地方性传播创造了潜力。为了减轻这种溢出，首先有必要划定 CHIKV 丛林蚊子媒介的分布，确定塑造这些分布的环境因素，并确定蚊子的存在与病毒溢出的关键驱动因素（包括蚊子和 CHIKV 丰度）之间的关联。因此，我们使用最大熵模型在塞内加尔的凯杜古连续两个雨季对七种 CHIKV 蚊子媒介的分布进行了建模。
在研究区域的五个土地覆盖类别中的五十个地点收集了蚊子数据。模型中包含了代表土地覆盖、地形和气候因素的环境数据。使用接收者操作特征曲线（AUROC）统计数据比较和评估模型。测试了模型输出与单个蚊子物种以及 CHIKV 阳性蚊子群丰度的相关性。
制作并评估了 14 个模型；与蚊子分布最密切相关的环境变量是到大面积森林的距离、景观斑块大小、降雨量和归一化植被指数（NDVI）。七个模型与蚊子丰度呈正相关，一个（Aedes taylori）与 CHIKV 阳性蚊子群呈一致的正相关。八个模型预测了 Tenkoto 和 Ngary 村庄附近蚊子的相对高发生率，这两个地区是 CHIKV 阳性蚊子群出现频率最高的地区。
在所考虑的环境因素中，景观破碎度和配置对蚊子分布的影响最大。在所建模的蚊子物种中，Ae. taylori 的分布与 CHIKV 的丰度相关性最强，这表明该物种的存在将是预测丛林 CHIKV 存在的有用指标。
