Experimental comparison of Baylisascaris procyonis definitive host competence between domestic dogs and raccoons ( Procyon lotor) .

Domestic dogs can function as either paratenic or definitive hosts for the zoonotic raccoon roundwormBaylisascaris procyonis. However, factors leading to development of patent infections in dogs are under-studied. Here we compared infection dynamics ofB. procyonisin dogsvsthe natural raccoon host. Dogs and raccoons were inoculated 5000 or 500B. procyoniseggs (n= 3 per dose) or were fedB. procyonis-infected laboratory mice (n= 3 per dose; mice inoculated with 1000 or 250 eggs). Fecal samples were analysedviaflotation and a commercial coproantigen ELISA designed for detection ofToxocaraspp. Two of 12 dogs (both received low dose larvae) developed patent infections; all 12 raccoons became infected with 10 developing patent infections. Compared with dogs, prepatent periods were shorter in raccoons and maximum egg outputs were much greater.Baylisascaris procyoniscoproantigens were detectableviaELISA in all raccoons and the patently infected dogs. Finally, dogs spontaneously lost infections while all patently infected raccoons shed eggs until conclusion of the study. Our results demonstrate that dogs are clearly suboptimal hosts showing limited parasite establishment and fecundityvsraccoons. Despite the low competence, patently infected dogs still pose a risk for human exposure, emphasizing the importance of control measures.