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J Med Entomol. 2018 Jun 28;55(4):1016-1026. doi: 10.1093/jme/tjy030.

Passive Tick Surveillance Provides an Accurate Early Signal of Emerging Lyme Disease Risk and Human Cases in Southern Canada.

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Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montréal, Saint-Hyacinthe, QC, Canada.
Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculty of Veterinary Medicine, University of Montréal, Saint-Hyacinthe, Canada.
Direction des risques biologiques et de la santé au travail, Institut national de santé publique du Québec, Montréal, Canada.
Policy Integration and Zoonoses Division, Centre for Foodborne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Saint-Hyacinthe, Canada.
Zoonoses and Special Pathogens Division, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Canada.
Public Health Risk Sciences Division, National Microbiology, Public Health Agency of Canada, Saint-Hyacinthe, Canada.
Direction de santé publique de la Montérégie, Centre intégré de santé et de services sociaux Montérégie-Centre, Longueuil, Canada.
Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Chemin Sainte-Marie, Sainte-Anne-de-Bellevue, Canada.
Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Canada.


Lyme disease is an emerging public health threat in Canada. In this context, rapid detection of new risk areas is essential for timely application of prevention and control measures. In Canada, information on Lyme disease risk is collected through three surveillance activities: active tick surveillance, passive tick surveillance, and reported human cases. However, each method has shortcomings that limit its ability to rapidly and reliably identify new risk areas. We investigated the relationships between risk signals provided by human cases, passive and active tick surveillance to assess the performance of tick surveillance for early detection of emerging risk areas. We used regression models to investigate the relationships between the reported human cases, Ixodes scapularis (Say; Acari: Ixodidae) ticks collected on humans through passive surveillance and the density of nymphs collected by active surveillance from 2009 to 2014 in the province of Quebec. We then developed new risk indicators and validated their ability to discriminate risk levels used by provincial public health authorities. While there was a significant positive relationship between the risk signals provided all three surveillance methods, the strongest association was between passive tick surveillance and reported human cases. Passive tick submissions were a reasonable indicator of the abundance of ticks in the environment (sensitivity and specificity [Se and Sp] < 0.70), but were a much better indicator of municipalities with more than three human cases reported over 5 yr (Se = 0.88; Sp = 0.90). These results suggest that passive tick surveillance provides a timely and reliable signal of emerging risk areas for Lyme disease in Canada.

[Indexed for MEDLINE]

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