Comparison of 4 Giardia Diagnostic Tests in Diagnosis of Naturally Acquired Canine Chronic Subclinical Giardiasis
Article first published online: 28 JAN 2010
Copyright © 2010 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 24, Issue 2, pages 293–297, March/April 2010
How to Cite
Rishniw, M., Liotta, J., Bellosa, M., Bowman, D. and Simpson, K.W. (2010), Comparison of 4 Giardia Diagnostic Tests in Diagnosis of Naturally Acquired Canine Chronic Subclinical Giardiasis. Journal of Veterinary Internal Medicine, 24: 293–297. doi: 10.1111/j.1939-1676.2010.0475.x
- Issue published online: 1 MAR 2010
- Article first published online: 28 JAN 2010
- Submitted August 12, 2009; Revised November 17, 2009; Accepted December 22, 2009.
Vol. 24, Issue 3, 797, Article first published online: 7 MAY 2010
- Fecal antigen;
- Fluorescent antibody;
- Zinc sulfate
Background: The performance of Giardia diagnostic tests that detect either cysts or fecal antigens has not been thoroughly examined.
Hypothesis/Objectives: We examined the concordance and agreement among 4 Giardia diagnostic tests (2 cyst and 2 coproantigen detection methods) in a colony of dogs chronically and subclinically infected with Giardia.
Animals: Twenty dogs with chronic, subclinical Giardia infection.
Methods: Giardia diagnostic tests were performed repeatedly on each dog over 120 days. Fecal cyst detection methods (ZnSO4 flotation and fluorescent antibody [FAB] coproscopy) were performed 3 times per week. Coproantigen methods (Giardia SNAP test and quantitative ELISA) were performed weekly. Results were analyzed and compared among methods.
Results: When compared with FAB coproscopy, all of the in-house diagnostic tests had excellent positive predictive values (PPVs, 95–99%) at the study prevalence (89%). At lower prevalence rates, ZnSO4, SNAP, and ELISA tests all had good negative predictive values (NPVs), but poor PPVs. There was poor to good agreement among tests by κ analysis.
Conclusion and Clinical Relevance: Our findings show that most commonly used in-house Giardia diagnostic tests have poor agreement with the gold standard method (FAB coproscopy). The in-house tests have good NPVs, but poor PPVs, at prevalence rates common in most clinical settings.