Peer-reviewed veterinary case report
Best ways to test for Giardia in dogs and cats
By Saleh, Meriam N et al.·Published in Journal of veterinary internal medicine·2019·Department of Biomedical Sciences & Pathobiology·View original on PubMed →
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Original publication title: Comparison of diagnostic techniques for detection of Giardia duodenalis in dogs and cats.
Plain-English summary
Researchers looked at different tests available in the U.S. to detect Giardia duodenalis, a parasite that can infect dogs and cats. They analyzed fecal samples from 388 pets in Colorado, Oklahoma, and Virginia using various methods, including a standard test called the direct immunofluorescent assay (IFA). The study found that all tested methods had good accuracy, with sensitivity (ability to correctly identify those with the infection) at 82% or higher and specificity (ability to correctly identify those without the infection) at 90% or higher. When combining results from one of the tests with the IFA, the differences in accuracy among the commercial tests became less significant. Overall, the findings suggest that using the IFA as a reference test is valid, and combining it with other testing methods can improve detection of Giardia in pets.
Abstract
BACKGROUND: An evaluation of currently available in-clinic diagnostic tests for Giardia duodenalis infection of dogs and cats has not been performed. In addition, there is discordance among published diagnostic comparisons. The absence of a true gold standard for detecting Giardia duodenalis also complicates diagnostic evaluations. OBJECTIVES: To evaluate diagnostic tests commercially available in the United States for detecting Giardia duodenalis in dogs and cats, in comparison to a widely used reference test, the direct immunofluorescent assay (IFA), and also to compare the results of 2 methods of analysis: comparison of diagnostic tests to a reference test (IFA) and Bayesian analysis. ANIMALS: Fecal samples from a convenience sample of 388 cats and dogs located in Colorado, Oklahoma, and Virginia. METHODS: Fecal samples were tested for Giardia duodenalis by zinc sulfate centrifugal fecal flotation and 4 different commercial diagnostic immunoassays. Results were analyzed via Bayesian analysis and by comparison to the IFA as the reference test. RESULTS: Sensitivity and specificity by comparison to IFA was ≥82% and ≥90%, respectively, for all diagnostic tests in dogs and cats. When analyzed via Bayesian analysis, sensitivity and specificity were ≥83% and ≥95%, respectively. When ZnSOcentrifugal fecal flotation results were combined with immunoassay results, there was no longer a significant difference between the sensitivities of the commercial in-clinic immunoassays. CONCLUSION AND CLINICAL RELEVANCE: The Bayesian analysis validates using IFA as the reference test. Differences in commercial in-clinic immunoassay sensitivities can be mitigated when the results are combined with ZnSOcentrifugal fecal flotation results.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/30982235/