Spatial Risk Model for Ixodes scapularis-Borne Borrelia

我们建议测量螺旋体螺旋体在美国整个地理范围内从肩部硬蜱向人类传播的风险，并基于媒介种群密度和疏螺旋体感染流行率开发和验证空间显式风险模型。寻找寄主若虫的密度。将通过在选定的州9方舟或自然区的95个位置，以2度网格样方间隔覆盖已知物种范围的闭合树冠落叶森林生境的拖曳采样来测量肩胛骨。 从这些地点采集的100只扁虱样本将通过16S rDNA(RRS)基因的实时定量聚合酶链式反应(RT-PCR)进行检测，以鉴定螺旋体属。螺旋体进一步鉴定到亚种水平将通过RT-PCR和特定的DNA探针和核苷酸测序来完成。在每个地点的若虫中发现的螺旋体的种类、基因种和亚种的遗传结构将以相对频率的形式进行数学表达。频率值将与扁虱密度估计值相结合以进行估计 每个样本点的人类感染风险。将开发利用遥感环境数据、地理信息系统和空间统计的空间模型，以预测未抽样地区的风险，并提供连续的地形图，描绘整个范围内的风险。肩胛骨。将在四个项目年的每一年中重复采样，总共提供大约400个采样点和预期的5000个疏螺旋体基因测定。随后每年的数据将用于验证前几年的模型预测，从而积累为期四年的项目的准确性。最终的产品将是一张人类感染由我肩周炎传播的螺旋体的风险的表面地图。 对于美国来说，

We propose to measure the risk of Borrelia spirochete transmission to humans from Ixodes scapularis ticks throughout its geographic range in the U.S. and to develop and validate a spatially explicit risk model based upon vector population density and Borrelia infection prevalence. The density of host-seeking nymphal [. scapularis will be measured by drag sampling of closed-canopy deciduous forest habitats in selected state 9arks or natural areas at 95 locations spaced among 2 degree grid quadrats covering the known species range. Samples of 100 ticks collected from these sites will be assayed by real-time quantitative polymerase chain reaction (RT-PCR) of the 16S rDNA (rrs) gene for identification of genus Borrelia spirochetes. Further characterization of Borrelia spirochetes to subgenospecies levels will be accomplished by RT-PCR with specific DNA probes and nucleotide sequencing. The species, genospecies,and subgenospecies genetic structure of Borrelia spirochetes found in nymphal I. scapularis at each site will be mathematically expressed in terms of relative frequency. The frequency values will be combined with tick density estimates to estimate the risk of human infection at each sample site. Spatial models, employing remotely-sensed environmental data, geographic information systems, and spatial statistics, will be developed to predict risk in unsampled areas and provide a continuous surface map depicting risk throughout the range of/. scapularis. Sampling will be repeated during each of four project years, providing a total of approximately 400 sampling points and an anticipated 5,000 Borrelia genotype determinations. Data from each subsequent year will be used to validate model prediction from previous years, thus accumulating accuracy over the four-year project. The final product will be a surface map of human risk for infection from I. scapularis-borne Borrelia spirochetes for the U.S.