Eastern cottontails (Sylvilagus floridanus) as hosts for ticks infected with Borrelia burgdorferi, Anaplasma phagocytophilum, and Powassan virus in Virginia, USA.

Abstract

Tick-borne pathogen infections are an increasing occurrence globally, yet many aspects of pathogen maintenance and host-tick interactions remain poorly understood. Here we consider the potential role of eastern cottontails (Sylvilagus floridanus) in the enzootic cycles of tick-borne pathogens of medical importance in Virginia. Over a 3-year period, ticks and blood were collected from rabbits acquired through passive surveillance in 21 counties in Virginia. Seven hundred seventy ticks were collected from 90 of the 121 rabbits examined in this study. Tick species collected from the rabbits included Haemaphysalis leporispalustris, Haemaphysalis longicornis, Amblyomma americanum, Dermacentor variabilis, and Ixodes spp. Ticks identified as Ixodes spp. and H. leporispalustris were tested in pools for Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum, and Powassan virus (POWV). Borrelia burgdorferi and A. phagocytophilum were detected in several Ixodes spp. pools yielding a pooled infection rate of 4.6% and 3.7%, respectively. These bacterial pathogens along with POWV were detected in pools of H. leporispalustris yielding pooled infection rates of 0.2%, 0.2%, and 0.5%, respectively. In addition, 3 rabbits were found to have neutralizing antibodies against POWV indicating exposure to this tick-borne flavivirus. We describe the presence of infected ticks (including juvenile ticks that could bite humans as adults) utilizing rabbits as hosts, as well as evidence of POWV infection (1.75% seroprevalence) in rabbit sera. These results provide useful information about the role of rabbits as hosts to infected ticks, though cannot ascertain their role in the maintenance or the transfer of pathogens from the rabbits to naïve ticks. Future studies are warranted to explore any additional roles these and other lagomorphs may be playing in the enzootic cycle of tick-borne pathogens.