Giardia and other intestinal parasites in different dog populations in Northern Belgium.

The objectives of this study were to obtain data on the prevalence of intestinal parasites in different dog populations in northern Belgium, to estimate the zoonotic risk associated with these infections and to identify potential risk factors. Between 2004 and 2007 a total of 1159 faecal samples were collected from 451 household dogs, 357 dogs from breeding kennels and 351 dogs with gastrointestinal disorders. The samples from dogs with gastrointestinal disorders were sent to the diagnostic Laboratory for Parasitology at Ghent University by veterinary practitioners. In household dogs the prevalence of intestinal parasites was relatively low. Giardia was the most commonly found parasite (9.3%, CI 5.5-13.1), followed by Toxocara canis (4.4%, CI 2.7-6.8). Much higher infection rates were observed in kennel dogs, especially for Giardia spp. (43.9%, CI 37.8-50.0); T. canis (26.3%, CI 21.8-31.2) and Cystoisospora spp. (26.3%, CI 21.8-31.2). Also in dogs with gastrointestinal problems, Giardia spp. (18.1%, CI 13.1-23.1), Cystoisospora spp. (8.8%, CI 6.1-12.3) and T. canis (7.4%, CI 4.9-10.7) were the most frequently detected parasites. In all dog populations pups were more frequently infected with Cystoisospora (P<0.0001 to P<0.05), Giardia (P<0.001 to P<0.05), and T. canis (P<0.0001 to P<0.001) than adult dogs, except for T. canis in household dogs, where this correlation was not significant. A significant association of anthelmintic treatment with T. canis infections was only observed within the household population. Household dogs with a higher number of treatments per year were more frequently infected with T. canis (P<0.05). There was a significant difference between the different breeding kennels for the occurrence of Cystoisospora, Giardia and T. canis (P<0.0001) and large kennels harboured relatively more infected animals than smaller breeding facilities (P<0.05). However, this was not significant for Giardia spp. Breed and gender did not affect the risk of an infection in any of the study populations. Toxocara and Giardia present a zoonotic risk, especially in household dogs, where the majority of Giardia positive samples (80%) belonged to the zoonotic assemblage A. In kennel dogs and clinically affected dogs the host-specific Giardia assemblages C and D were most prevalent (94% and 80%, respectively).