Evaluating the effect of residential deer-exclusion fencing on host-seeking Ixodes scapularis ticks

Blacklegged ticks (Ixodes scapularis) are vectors of multiple human pathogens and are often encountered in residential settings of the northeastern United States. Deer-excluding fencing has been suggested as a method to reduce residential I. scapularis abundance, but little scientific evidence supports this recommendation on properties ≤6 hectares. We measured I. scapularis density in tick habitat inside and outside deer fencing on 16 residential (treatment) properties and 16 matched unfenced (control) properties in Fairfield County, Connecticut (n=10), Westchester County, New York (n=6), and Washington County, Rhode Island (n=16). Although overall I. scapularis densities (ticks per meter) were slightly higher in tick habitat within unfenced control properties (adults: mean = 0.095, SD = 0.034; nymphs: mean = 0.040; SD = 0.015) compared to within fenced areas at treatment properties (adults: mean = 0.045; SD = 0.020; nymphs: mean = 0.027; SD = 0.010), we did not detect a significant difference (Wilcoxon z, p >0.05). Similarly, prevalence of tick infection with Borrelia burgdorferi, Borrelia miyamotoi, Babesia microti, Babesia odocoilei, and Anaplasma phagocytophilum) did not differ significantly between treatment and control properties (p >0.05). Our findings suggest that deer exclusion alone may not be an effective tick management tactic for properties ≤6 hectares, and that the overall host community is an important driver of tick densities at this fine scale.