Effect of Urbanization on Neospora caninum Seroprevalence in White-Tailed Deer (Odocoileus virginianus)

The protozoan Neospora caninum is transmitted between domestic and wildlife species. Urbanized environments and deer density may facilitate this transmission and play a critical role in the spillover of N. caninum from domestic animals to wildlife. White-tailed deer (Odocoileus virginianus; WTD) are an important intermediate host for maintaining the sylvatic cycle of N. caninum in the USA. Here, we assayed serum samples from 444 WTD from a nature reservation across a suburban to urban gradient in Ohio, USA. Antibodies to N. caninum were found by using a recombinant NcGRA6 ELISA in 23.6% (105/444). Significant risk factors for seropositivity were age class and urbanization. Deer from urbanized environments were at greater odds of being seropositive (89/323, 27.6%) than those from suburban habitats (16/121, 13.2%), and this difference persisted when adjusting for age and sex. Age was also a significant risk factor with adults at greater odds to be seropositive than fawns and yearlings. We speculate the main route of exposure in WTD is ingestion of N. caninum oocysts from contaminated environments and urbanized habitats facilitate this exposure.