Background: Lyme disease (LD) is an increasing public health threat in temperate zones of the northern hemisphere, yet relatively few methods exist for reducing LD risk in endemic areas. Disrupting the LD transmission cycle in nature is a promising avenue for risk reduction. This experimental study evaluated the efficacy of fluralaner, a recent oral acaricide with a long duration of effect in dogs, for killing Ixodes scapularis ticks in Peromyscus maniculatus mice, a known wildlife reservoir for Borrelia burgdorferi in nature. Methods: We assigned 87 mice to 3 fluralaner treatment groups (50 mg/kg, 12.5 mg/kg and untreated control) administered as a single oral treatment. Mice were then infested with 20 Ixodes scapularis larvae at 2, 28 and 45 days post-treatment and we measured efficacy as the proportion of infesting larvae that died within 48 h. At each infestation, blood from 3 mice in each treatment group was tested to obtain fluralaner plasma concentrations (C p). Results: Treatment with 50 mg/kg and 12.5 mg/kg fluralaner killed 97% and 94% of infesting larvae 2 days post-treatment, but no significant effect of treatment on feeding larvae was observed 28 and 45 days post-treatment. Mouse C p did not differ significantly between the two tested doses. Mean C p decreased from 13,000 ng/ml in the 50 mg/kg group and 4000 ng/ml in the 12.5 mg/kg group at Day 2 to < 100 ng/ml in both groups at Day 45. Conclusions: We provide the first evidence that fluralaner is effective for killing immature ticks in Peromyscus mice, a first step in evaluating its potential for treating wild rodents as a public health intervention to reduce LD risk in endemic areas.

The development of interventions that reduce Lyme disease incidence remains a challenge. Reservoir-targeted approaches aiming to reduce tick densities or tick infection prevalence with Borrelia burgdorferi have emerged as promising ways to reduce the density of infected ticks. Acaricides of the isoxazoline family offer high potential for reducing infestation of ticks on small mammals as they have high efficacy at killing feeding ticks for a long period. Fluralaner baits were recently demonstrated as effective, in the laboratory, at killing Ixodes scapularis larvae infesting Peromyscus mice, the main reservoir for B. burgdorferi in northeastern North America. Here, effectiveness of this approach for reducing the infestation of small mammals by immature stages of I. scapularis was tested in a natural environment. Two densities of fluralaner baits (2.1 baits/1,000 m2 and 4.4 baits/1,000 m2) were used during three years in forest plots. The number of I. scapularis larvae and nymphs per mouse from treated and control plots were compared. Fluralaner baiting reduced the number of larvae per mouse by 68% (CI95: 51–79%) at 2.1 baits/1,000 m2 and by 86% (CI95: 77–92%) at 4.4 baits/1,000 m2. The number of nymphs per mouse was reduced by 72% (CI95: 22–90%) at 4.4 baits/1,000 m2 but was not significantly reduced at 2.1 baits/1,000 m2. Reduction of Peromyscus mouse infestation by immature stages of I. scapularis supports the hypothesis that an approach targeting reservoirs of B. burgdorferi with isoxazolines has the potential to reduce tick-borne disease risk by decreasing the density of infected ticks in the environment.

Integrated interventions coherent with the One Health approach are required to maximize the effectiveness of tick-borne disease prevention. The objective of this study was to evaluate the feasibility of a community-based One Health preventive intervention in a municipality reporting a high incidence of Lyme disease (LD) in the province of Quebec, Canada. The intervention integrated several activities to promote the adoption of preventive behaviours in the community (community component), with the reduction of infected ticks in the environment (environmental component). To evaluate short-term effects of the community component, quantitative data on knowledge, attitudes, and practices (KAP) of citizens were collected using online questionnaires at the beginning of the intervention and 1 year later. To evaluate the implementation of the intervention, a qualitative approach was principally used, and individual interviews (n=37) were conducted with key informants. Results showed that having a high level of participation in the community activities included in the intervention was associated with a higher adoption of preventive measures at the end of the intervention, although participation was not significantly associated with changes in KAP over the intervention period. Interviews revealed that the community mobilization approach was perceived as an effective and sustainable way to empower citizens and researchers with regard to LD prevention. This study suggests that community-based interventions of this type offer a promising approach to the prevention of tick-borne diseases.

Objective In 2021, a first outbreak of anaplasmosis occurred in animals and humans in southern Québec, with 64% of confirmed human cases located in Bromont municipality. Ixodes scapularis ticks and Peromyscus mouse ear biopsies collected in Bromont from 2019 to 2021 were analyzed for Anaplasma phagocytophilum (Ap) with the objective of determining whether an early environmental signal could have been detected before the outbreak. Methods Samples were collected for a concurrent study aiming to reduce Lyme disease risk. Between 2019 and 2021, up to 14 experimental sites were sampled for ticks and capture of small mammals took place on three sites in 2021. Samples were screened for Ap using multiplex real-time PCR, and genetic strains were identified using a single-nucleotide polymorphism assay. Results Analyses showed an increase of 5.7% in Ap prevalence in ticks (CI95: 1.5–9.9) between 2019 and 2020, i.e., one year before the outbreak. A majority of Ap-positive ticks were infected with the zoonotic strain (68.8%; CI95: 50.0–83.9) during the study period. In 2021, 2 of 59 captured Peromycus mice were positive for Ap, for a prevalence of 3.4% (CI95: 0.4–11.7). Conclusion We conclude that data collected in Bromont could have provided an early signal for an anaplasmosis risk increasing in the targeted region. This is a reminder that integrated surveillance of tick-borne diseases through structured One Health programs, i.e. systematically integrating data from humans, animals and the environment, can provide useful and timely information for better preparedness and response in public health.