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Comparing tick surveillance methods including public observations to determine their associations with Lyme disease risk
Fellin E, Varin M, Crandall K, Savage J, Millien V
Blacklegged tick (Ixodes scapularis) occurrence data is collected via active and passive tick surveillance methods. Active tick surveillance involves surveying a specific area via tick dragging and/or small mammal trapping while passive tick surveillance relies on tick submissions by public health units. Since these ticks are vectors of Borrelia burgdorferi, the causal agent of Lyme disease, tick surveillance data are used to predict areas for Lyme disease risk. Accurately estimating Lyme disease risk areas is crucial for public health; however, different data collection methods may result in the identification of varying risk areas or hotspots for disease. Here, we explored the relationship between human Lyme disease cases and tick distribution data from three surveillance methods across Québec. Active and passive tick surveillance data previously collected by the Québec Government were compared with human Lyme disease cases across Québec. eTick data, which consists of public passive observations of ticks and has not been used for monitoring Lyme disease before, were also considered. We predicted that the association between tick abundance estimated from distinct surveillance methods and human Lyme disease cases are context dependent, contingent on when the blacklegged tick occurrences were determined as well as the location (early emergence vs. established sites). We found that year and location had a significant association with the number of human Lyme disease cases, regardless of the tick surveillance method used to estimate tick abundance. There was a significantly positive relationship between human Lyme disease cases and tick abundance observed via passive and active surveillance, but not necessarily eTick submissions, possibly due to the recent development of the eTick platform. Exploring current surveillance methods can enhance Lyme disease risk predictions and improve monitoring of other tick-borne diseases in Québec.
