Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
National Microbiology Laboratory, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada.
PLoS One. 2018 Feb 27;13(2):e0193524. doi: 10.1371/journal.pone.0193524. eCollection 2018.
The emergence of the vector Ixodes scapularis in Ontario, Canada poses a significant public health risk. Both passive and active surveillance approaches have been employed by public health professionals (i.e., government employees) to monitor for the range expansion of this tick. Field surveillance using drag sampling for questing ticks is a recognized and effective method to identify reproducing tick populations. The degree of effort (i.e., number of visits per site) can enhance the sensitivity and specificity of surveillance, but increased effort conflicts with the cost to public health for field surveillance. Here we developed an indicator to determine the likelihood of I. scapularis establishment based on field sampling results. Field data from two established populations of I. scapularis in Ontario were incorporated with previous analyses of surveillance data to create the indicator, which is in the form of a scoring system. The life stage(s) collected, overall abundance and past surveillance findings from a site are all considered and a level is assigned for the likelihood of I. scapularis establishment based on current field sampling results. The likelihood levels are non-zero (i.e., no I. scapularis detected, but risk still present due to adventitious ticks), low, medium or high, and recommendations for future surveillance and public health measures are provided. The indicator was validated against field sampling results from five other established sites in the province and correctly categorized all five areas as high likelihood of establishment. The indicator was also applied to field sampling results from 36 sites of unknown status that were visited twice during the period of 2014-2016. There was substantial agreement of levels between measurements, as calculated using a weighted kappa. The indicator can assist public health professionals with the interpretation of field sampling results and direct their efforts for ongoing surveillance and public health interventions for I. scapularis-borne diseases, including Lyme disease.
加拿大安大略省向量伊希斯 scapularis 的出现带来了重大的公共卫生风险。公共卫生专业人员（即政府雇员）采用了被动和主动监测方法来监测这种蜱的范围扩大。使用拖曳采样进行探查蜱的实地监测是识别繁殖蜱种群的一种公认且有效的方法。努力程度（即每个地点的访问次数）可以提高监测的敏感性和特异性，但增加努力与实地监测的公共卫生成本相冲突。在这里，我们根据实地采样结果开发了一种确定伊希斯 scapularis 建立可能性的指标。安大略省两个已建立的伊希斯 scapularis 种群的实地数据与以前对监测数据的分析相结合，创建了该指标，该指标采用评分系统的形式。所收集的生命阶段、总体丰度以及来自一个地点的过去监测结果都被考虑在内，并根据当前实地采样结果为伊希斯 scapularis 建立的可能性分配一个级别。可能性级别不为零（即，未检测到伊希斯 scapularis，但由于偶然的蜱虫仍存在风险），低、中或高，并提供了对未来监测和公共卫生措施的建议。该指标针对该省其他五个已建立地点的实地采样结果进行了验证，并正确地将所有五个地区归类为高建立可能性。该指标还应用于 2014 年至 2016 年期间两次访问的 36 个未知状态的实地采样结果。使用加权 kappa 计算，测量值之间的水平具有实质性一致性。该指标可以帮助公共卫生专业人员解释实地采样结果，并指导他们进行伊希斯 scapularis 传播疾病（包括莱姆病）的持续监测和公共卫生干预。
