Sentinel Surveillance Contributes to Tracking Lyme Disease Spatiotemporal Risk Trends in Southern Quebec, Canada

This study, undertaken by Quebec researchers between 2015 and 2019, focusses on regions of southern Quebec that boast the highest provincial rates of Lyme disease in an effort to determine if a cost-effective approach to monitoring Lyme disease risk in a large territory over many years could be developed. In all, 21 sites located within provincial or regional parks known to have emerging blacklegged tick populations and appropriate forest composition were selected for sampling twice per year. These researchers used nymph density -- instead of the more common infected nymph density metric -- to predict rates of human Lyme disease cases in each region. Ultimately they conclude that nymph density performs almost as well as the more complicated, expensive methods that are currently used to predict risk. However they note that for nymph density to be sufficiently predictive in a region, it needs to be considered alongside other factors such as geography and ecology. Because of this, they caution that results may not apply to other regions. It's notable that the model did not perform well in the Estrie region of Quebec where most of the Lyme disease cases are diagnosed for reasons researchers could only guess at.