Repellent efficacy of a novel essential oil-based fabric spray formulation against <i>Ixodes scapularis</i> and <i>Dermacentor variabilis</i> ticks in laboratory conditions and human trials

The increased prevalence of ticks and tick-borne diseases, combined with health concerns about synthetic repellents, has prompted research into natural alternatives. Products applied to fabric have become more popular, and currently, permethrin is the only active ingredient used in fabric-applied repellents, although consumer use is restricted in Canada. We evaluated the repellency of Citriodiol (lemon eucalyptus essential oil) alone and delivered in a novel fabric spray formulation (AtlanTick Fabric Spray) against Ixodes scapularis and Dermacentor variabilis ticks. Citriodiol oil exhibited overall repellency against I. scapularis nymphs across all concentrations, and none differed significantly from DEET 25% (v/v). In horizontal assays, Citriodiol at 10% v/v (chronic assay) repelled more than 90% of nymphs up to 4 h. When delivered in a fabric spray formulation, it was more effective at repelling ticks overall. In the Y-tube assays, square assays, and human trials, the AtlanTick Fabric Spray applied on different fabric types repelled female adults of both tick species. Repellency reached 100% in square arena trials for up to 3 d post-treatment (cotton) and remained above 70% at 2 wk against I. scapularis across all fabric types. In human trials, repellency remained above 95% for up to 1 wk post-treatment for I. scapularis. For D. variabilis, repellency remained above 95% on all fabric types for 3 d post-treatment but declined after 7 d on synthetic fabrics. The new fabric spray offers an innovative alternative to permethrin-based fabric spray products for repelling ticks and reducing the spread of tick-borne diseases.