A Bayesian evaluation of three diagnostic assays for the detection of Giardia duodenalis in symptomatic and asymptomatic dogs

Endoparasite prevalence and recurrence across different age groups of dogs and cats

The apparent prevalence of endoparasite infections across different age groups was calculated from 6555 dogs and 1566 cats that had a fecal examination performed upon presentation to the Veterinary Hospital of the University of Pennsylvania between 1997 and 2007. Based on notations from the medical history indicating prior parasite infections, estimates of recurrence were generated for each common group of parasites, including Trichuris, Giardia, ascarids, hookworms, Cystoisospora, and tapeworms. Endoparasitism was predominantly a disease of younger animals, with peak prevalence observed almost uniformly in dogs under 6 months old, with the exception of Trichuris with its longer pre-patent period, and in cats less than 18 months old. Furthermore, nearly 50% of dogs under 6 months old with a history of parasites, were diagnosed with at least one species of parasite on subsequent fecal examination. The percentage dropped to 18.4% in animals aged 1-4 years, but again increased to 31.5% in animals over 10 years old. There was no reported recurrence of Giardia or Cystoisospora from canine or feline patients older than 1 year. The recurrence of whipworm rose steadily with age, while hookworm and roundworm recurrence peaked in patients 1-4 years old. Findings from the study emphasize the importance of follow up fecal examinations and treatments in patients diagnosed with endoparasites.

Transmission cycles of Giardia duodenalis in dogs and humans in Temple communities in Bangkok--a critical evaluation of its prevalence using three diagnostic tests in the field in the absence of a gold standard

The prevalence and associated risk factors for Giardia duodenalis in canine and human populations in Temple communities of Bangkok, Thailand were determined by evaluating three common diagnostic methods utilised to detect Giardia, namely zinc sulphate flotation and microscopy, an immunofluoresence antibody test and nested polymerase chain reaction (PCR) based on the SSU-rDNA gene. The diagnostic sensitivity and specificity together with the negative and positive predictive values of each test were evaluated in the absence of a gold standard using a Bayesian approach. The median estimates of the prevalence of infection with G. duodenalis in dogs and humans in Thailand were 56.8% (95% PCI, 30.4%, 77.7%) and 20.3% (95% PCI, 7.3%, 46.3%) respectively. PCR and immunofluorescence antibody tests (IFAT) were the most accurate tests overall with diagnostic sensitivity and specificity of 97.4% (95% PCI, 88.5%, 99.9%) and 56.2% (95% PCI, 40.4%, 82.9%) for the PCR and 61.8% (95% PCI, 40.8%, 99.1%) and 94.7% (95% PCI, 87.4%, 99.1%) for IFAT respectively Three cycles, anthroponotic, zoonotic and dog-specific cycles of G. duodenalis were shown to be operating among the human and canine populations in these Temple communities in Bangkok, supporting the role of the dog as a potential reservoir for Giardia infections in humans.

Is Giardia a significant pathogen in production animals?

Although Giardia duodenalis is recognised worldwide as the most important parasitic cause of gastro-intestinal disorder in human patients, the relevance of infection in production animals is prone to debate. Since the 1980s, clinical disease has been associated with giardiasis in production animals, both in natural conditions and in experimental studies. However, most Giardia research is focussed on the relevance of production animals as a reservoir for zoonotic transmission. In this study, the current knowledge on clinical relevance of giardiasis in production animals is reviewed, along with the diagnosis, treatment and control of infection. Furthermore, future research objectives are discussed.

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).