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

Abstract

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.

Fasciola and fasciolosis in ruminants in Europe: Identifying research needs

“…Infection can be also confirmed at necropsy and many farmers use abattoir returns to identify if F. hepatica is present in their livestock (Mazeri, Sargison, Kelly, Bronsvoort, & Handel, ).…”

“…Infection can be also confirmed at necropsy and many farmers use abattoir returns to identify if F. hepatica is present in their livestock (Mazeri, Sargison, Kelly, Bronsvoort, & Handel, 2016). The MM3-COPRO test, based on the MM3 MoAb that binds to both CatL1 and CatL2 proteases (Mezo, Gonz alez-Warleta, Carro, & Ubeira, 2004), is commercialized by BIO X Diagnostics (La Jemelle, Belgium).…”

Modelling the variation in skin-test tuberculin reactions, post-mortem lesion counts and case pathology in tuberculosis-exposed cattle: Effects of animal characteristics, histories and co-infection

“…As Th1 responses are associated with lesion development in bTB, the presence of liver fluke infection could promote a shift towards a Th2‐type immune response and potentially restrain the progression of lesion development. It should be noted that surveillance data have less than perfect sensitivity or specificity in detecting liver fluke (recent European studies suggest sensitivity of 0.63–0.68 and specificity 0.88–1.00; Mazeri, Sargison, Kelly, Bronsvoort, & Handel, ; Rapsch et al., ), which could impact on our inferences here (potentially conservatively biasing our inferences towards the null; Schennach, ). Indeed, similarly, the ability to detect bTB visible lesions at slaughter is less than perfect (though specificity is close to 1; Lahuerta‐Marin et al., ), which is a general limitation to these study types (e.g., Downs et al., ; O'Hagan et al., ; Olea‐Popelka et al., ; Wright et al., ).…”

Zoonotic Trematodiasis

“…Several draft genome efforts are reported for S. mansoni [54] and S. haematobium [55], similar efforts detailing transcriptomics and proteomics data sets for S. japonicum are available [52,56,57]. A number of expressed sequence tags have been described for Fish-borne zoonotic trematodes such as O. viverrini [58], and the sequence of genes coding for hundreds of important invasive factors are described for F. hepatica [28,59].…”