Evaluation of the Performance of Five Diagnostic Tests for Fasciola hepatica Infection in Naturally Infected Cattle Using a Bayesian No Gold Standard Approach

• Published in: PloS one Vol. 11; no. 8; p. e0161621
• Main Authors: Mazeri, Stella, Sargison, Neil, Kelly, Robert F, Bronsvoort, Barend M deC, Handel, Ian
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.08.2016; Public Library of Science (PLoS)
• Subjects: Abattoirs; Animal Husbandry; Animals; Antigens; Bayes Theorem; Bayesian analysis; Beef cattle; Biology and Life Sciences; Bovidae; Cattle; Cattle - parasitology; Cattle Diseases - diagnosis; Causes of; Chronic infection; Counting; Diagnosis; Diagnostic systems; Diagnostic tests; Diseases and pests; Economic importance; Enzyme-Linked Immunosorbent Assay; Epidemiology; Evaluation; Fasciola hepatica; Fascioliasis - diagnosis; Fascioliasis - veterinary; Feces - parasitology; Fluke infections; Gallbladder; Gallbladder - parasitology; Geography; Health planning; Infections; Inspection; Liver; Liver - parasitology; Meat; Medical diagnosis; Medicine and Health Sciences; Parasite Egg Count - veterinary; Parasites; Parasitology; Physical Sciences; Predictive Value of Tests; Research and Analysis Methods; Seasons; Sensitivity; Sheep; Trematoda; United Kingdom; Urinary bladder; Veterinary medicine; United Kingdom
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0161621

The clinical and economic importance of fasciolosis has been recognised for centuries, yet diagnostic tests available for cattle are far from perfect. Test evaluation has mainly been carried out using gold standard approaches or under experimental settings, the limitations of which are well known. In this study, a Bayesian no gold standard approach was used to estimate the diagnostic sensitivity and specificity of five tests for fasciolosis in cattle. These included detailed liver necropsy including gall bladder egg count, faecal egg counting, a commercially available copro-antigen ELISA, an in-house serum excretory/secretory antibody ELISA and routine abattoir liver inspection. In total 619 cattle slaughtered at one of Scotland's biggest abattoirs were sampled, during three sampling periods spanning summer 2013, winter 2014 and autumn 2014. Test sensitivities and specificities were estimated using an extension of the Hui Walter no gold standard model, where estimates were allowed to vary between seasons if tests were a priori believed to perform differently for any reason. The results of this analysis provide novel information on the performance of these tests in a naturally infected cattle population and at different times of the year where different levels of acute or chronic infection are expected. Accurate estimates of sensitivity and specificity will allow for routine abattoir liver inspection to be used as a tool for monitoring the epidemiology of F. hepatica as well as evaluating herd health planning. Furthermore, the results provide evidence to suggest that the copro-antigen ELISA does not cross-react with Calicophoron daubneyi rumen fluke parasites, while the serum antibody ELISA does.