One Health approach on toxocariasis and ophthalmic assessment in owners and dogs

Although toxocariasis has been considered a common and important neglected zoonotic parasitic disease worldwide, serologic ownership risk and owner-dog concomitant ophthalmic assessment remain to be fully established. Meanwhile, high toxocariasis prevalence has been recently found in seashore areas of southern Brazil. Accordingly, the present study aimed to perform owner serologic, fecal/hair dog, and owner- dog ophthalmic assessment in an endemic seashore area of southern Brazil. In overall, 112/342 (32.75%) owners were seropositive to anti-Toxocara spp. IgG antibodies by ELISA, with family income statistically significant (p = 0.007) as associated risk factor in the univariate analysis. In addition, Toxocara spp. eggs were visualized in only 6/216 (2.78%) dog feces and 5/236 (2.12%) dog hair samples. Logistic regression indicated that untreated water increased 6.3-fold the dog likelihood for T. canis eggs in hair or feces, while purebred dogs and outdoor access were considered as associated protective factors. Only one/342 individual presented highly suggestive ocular toxocariasis, in one eye and at the cicatricial stage (seropositive for anti-Toxocara IgG antibodies). Out of an additional 32 individuals with some degree of retinal scarring compatible with prior chorioretinitis, 10/32 (31.3%) were also seropositive for anti-Toxocara IgG antibodies. In addition, ophthalmic abnormalities were identified in 205/237 (86.5%) examined dogs, with the most frequent findings involving various nonspecific chronic lesions in 177/237 (74.7%), followed by Florida Spot Keratopathy (FSK) in 12/237 (5.1%) and retinopathy in 11/237 (4.6%) dogs. FSK prevalence in dogs was considered very high. Although less prevalent, fundoscopic changes were significantly associated with Toxocara spp. in both owners and their dogs. In conclusion, similar ophthalmologic abnormalities associated with shared environmental exposure to Toxocara spp. have highlighted the importance of One Health approach for holistic interpretation of human-dog natural occurrence of toxocariasis.