Raccoon roundworm prevalence (Baylisascaris procyonis) at the North Carolina Zoo, USA.

Baylisascaris procyonis is an important zoonotic nematode of raccoons (Procyon lotor). Infection with this parasite has important health implications for humans, zoo animals, and free-ranging wildlife. As a large, natural habitat zoo, the North Carolina Zoo (NC Zoo) coexists with native wildlife. Raccoons are abundant at the NC Zoo and the prevalence of B. procyonis is unknown. Raccoon latrines were located through employee reporting and systematic searching throughout the zoo and sampled for B. procyonis in October and November of 2018 and 2019. Parasite prevalence, latrine location, substrate category and latrine persistence were recorded. Thirty-three latrines were located in 2018 and eight new latrines in 2019 while four latrines from the prior year were no longer available to be sampled. Of the 29 latrines sampled over the two years, 16 (55%) persisted for at least one year. The majority of the latrines were found on natural substrate with rock showing the highest preference. Just over half (n = 21 of 41 total) of the active latrines in the study were in or immediately adjacent to animal enclosures. Two latrines were found in public areas including one contaminating children's play equipment. Additionally, fresh fecal samples were collected from five adult raccoons presented to the zoo's veterinary clinic in 2018 and 2019. All fecal samples tested by centrifugal flotation for both years were negative for B. procyonis. The results of this study show the value of field sampling to properly assess risk and enable informed decision-making regarding public health and wildlife management.