Risks To Human Health From Intestinal Parasites Carried By Household Dogs

Abstract

Introduction. Many intestinal parasites of dogs are zoonoses with high prevalence in humans, however the potential risk of zoonotic transmission is unknown. We evaluated the prevalence of intestinal parasites with zoonotic potential in dogs and the relationship between owners and their dogs. Methods. Fecal samples were collected from household dogs attended by veterinary clinics (n = 500) in São Paulo metropolitan area. The owners of these animals responded to a questionnaire addressing management issues and interaction with pets. Fecal samples examined microscopically were by flotation test. Giardia and Cryptosporidium antigens were detected using the direct immunofluorescence assay. Results. The prevalence of zoonotic intestinal parasites was: 20% of Giardia sp., 16% of Toxocara canis, 11% of Ancylostoma sp., and 6% of Cryptosporidium sp. We observed that: 70% of dogs were adopted from shelters or the street (95% CI: 58-84.6), 70% have access to rooms, 57% (95% CI: 47.4-63.5) sleep in bed, 58% (95% CI: 46-67) received licks of dogs, and 93% (95% CI: 85-98) do not perform fecal exams. The risk of presence of zoonotic intestinal parasites increased: in puppies (RR = 4.8; 95% CI: 3.1-6.2), in home with more than 2 dogs (RR = 2.0; 95% CI: 1.3 -3.1), outdoor access (RR = 1.5; 95% CI: 0.85-2.6) and irregularly antiparasitic drug use (RR = 2.1; 95% CI: 1.1-2.9). Discussion. The proximity and close relationship that the owner has with his dogs was very clear in this study. Unlike Toxocara and Ancylostoma, whose eggs become infective after a period in the environment, Giardia cysts and Cryptosporidium oocysts are infectious when eliminated in the feces and sometimes get in the fur of animals favoring the transmission through direct contact. The fact that the animals are not treated against parasites and not undergoing stool tests is indicator the neglect of parasitic zoonoses. Therefore, the proximity of dogs and their owners increases the risk of zoonotic transmission.