Experimental comparison of <i>Baylisascaris procyonis</i> definitive host competence between domestic dogs and raccoons (<i>Procyon lotor</i>)

AbstractDomestic dogs can function as either paratenic or definitive hosts for the zoonotic raccoon roundworm Baylisascaris procyonis. However, factors leading to development of patent infections in dogs are under-studied. Here we compared infection dynamics of B. procyonis in dogs vs the natural raccoon host. Dogs and raccoons were inoculated 5000 or 500 B. procyonis eggs (n = 3 per dose) or were fed B. procyonis-infected laboratory mice (n = 3 per dose; mice inoculated with 1000 or 250 eggs). Fecal samples were analysed via flotation and a commercial coproantigen ELISA designed for detection of Toxocara spp. 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 procyonis coproantigens were detectable via ELISA 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 fecundity vs raccoons. Despite the low competence, patently infected dogs still pose a risk for human exposure, emphasizing the importance of control measures.</jats:p

Enzyme-linked immunosorbent assay for coproantigen detection of <i>Trichuris vulpis</i> in dogs

Infections with Trichuris vulpis, the canine whipworm, may be challenging to diagnose even though characteristic bipolar eggs are shed by mature worms and may be recovered from feces. Decreased detection sensitivities because of using flotation solutions with specific gravities &lt;1.3 and a lengthy prepatent period can lessen the diagnostician’s ability to detect infection. Coproantigen detection in feces is becoming an accepted form of diagnosing parasitic infections and can circumvent some of the factors that affect egg recovery. The development of an enzyme-linked immunosorbent assay (ELISA) for the detection of whipworm-specific coproantigens in the feces of dogs with experimental and natural T. vulpis infections is reported herein. Whipworm-specific coproantigens were evidenced in feces from experimentally infected dogs using the newly developed ELISA starting as early as day 23 postinfection, while eggs were not detected in feces until day 69. In addition, 1,156 field fecal samples were tested using fecal flotation methods and the newly developed whipworm ELISA. Of these, 27 samples were found by flotation to be whipworm egg positive, while 35 had detectable antigen on the ELISA. Discrepant results were obtained in 12 samples; 2 egg-positive samples tested ELISA negative, and 10 ELISA-positive samples did not contain detectable egg levels. Using the fecal ELISA for the detection of whipworms in dogs should allow for earlier detection of infection, aid the identification of cases in the face of low egg shedding, and increase detection sensitivity as most commercial laboratories are using flotation solutions not optimal for T. vulpis egg detection. </jats:p