Protective and risk factors associated with the presence of Toxocara spp. eggs in dog hair

Toxocariasis is one of the most prevalent parasitic zoonoses in the world. The disease is principally caused by the nematode Toxocara canis, whose definitive host is the dog. The transmission of toxocariasis to humans is mainly caused by accidental ingestion of embryonated eggs of the parasite, present in the soil. Studies have shown that dog hair has the capacity to harbor eggs of the parasite and represents a risk for transmission of the zoonosis. The objective of the present study was to evaluate the frequency and factors associated with the contamination of dog hair by Toxocara spp. of animals attended and/or abandoned at a Veterinary-Teaching Hospital in Southeast Brazil. The hair samples were collected from the perineal region, and upper and lower tail regions. For analysis of the samples and recovery of Toxocara spp., the material was washed in Tween 20 and then filtered through sieves of 300 pm, 212 pm, and 38 pm. Hair samples from 165 dogs were analyzed. Of the analyzed samples, 59 (35.8%) were from puppies and 106 (64.2%) from adult animals. In the sample evaluation, 6.7% of the dogs (11/165) were contaminated, with a mean of 12.2 eggs per animal (1-70 eggs/animal) and 57.5 eggs/gram of hair. All the recovered eggs were not embryonated. There was an influence of age (puppies), breed (without defined breed), and origin (stray) of the dogs. On the other hand, deworming was a protective factor. Our results show that the risk of transmission of toxocariasis by direct contact, mainly in well-cared dogs, is low. Thus, prophylactic anthelmintic treatment and correct care regarding the hygiene of animals, especially puppies, should be recommended to reduce any risk of transmission of toxocariasis.