Gray areas: an investigation of ectoparasite abundance and distribution and tick-borne pathogens in peridomestic eastern gray squirrels Rodentia: Sciuridae (Sciurus carolinensis)

The eastern gray squirrel (Sciurus carolinensis Gmelin) is a widely distributed rodent in North America, including introduced populations in western regions. Despite being widespread in urban and suburban ecosystems, their role as reservoirs for tick-borne pathogens has been understudied compared to other wildlife hosts. This study investigates the prevalence of ectoparasites and tick-borne pathogens in eastern gray squirrels across suburban habitats in Centre County, Pennsylvania, United States. Over 2 yr, squirrels were trapped across 5 sites and examined for ectoparasites. Ticks were the most common ectoparasites identified, followed by lice, fleas, and mites (in order of prevalence). Ixodes scapularis Say was the only tick species identified. The head, particularly the ears, was the most frequently infested body region. In addition to ectoparasite surveillance, we assessed the presence of tick-borne pathogens in squirrels and pathogens in ticks. Squirrels were RNA-positive for Borrelia burgdorferi ([Johnson, Schmid, Hyde, Steigerwalt & Brenner]), Anaplasma phagocytophilum (Foggie, 1949), Borrelia miyamotoi (Franca, 1910) Fukunaga, Babesia microti, and Rickettsia rickettsii (Wolbach, 1919). ELISA screened 61 serum samples collected from individual squirrels for antibodies to the Borrelia burgdorferi VlsE and Anaplasma P44 proteins. Sixty-two and 17% were positive for antibodies to VlsE and P44, respectively, indicating past or current infection. The data presented collectively contribute to our better understanding of pathogen exposure in eastern gray squirrels. The results highlight the potential role of the eastern gray squirrel in vector ecology and the epidemiology of tick-borne diseases. Enhanced surveillance efforts in peridomestic areas are warranted and may mitigate zoonotic risks to humans and domestic animals.