Journal Article

Diagnostic performance of ELISA, IFAT and Western blot for the detection of anti-Leishmania infantum antibodies in cats using a Bayesian analysis without a gold standard

Vitale, Fabrizio, Delaunay, Pascal, Persichetti, Maria Flaminia, Marty, Pierre, Vullo, Angela, Masucci, Marisa, Pennisi, Maria Grazia, Solano-Gallego, Laia

2017

Overview

Background Anti- Leishmania antibodies are increasingly investigated in cats for epidemiological studies or for the diagnosis of clinical feline leishmaniosis. The immunofluorescent antibody test (IFAT), the enzyme-linked immunosorbent assay (ELISA) and western blot (WB) are the serological tests more frequently used. The aim of the present study was to assess diagnostic performance of IFAT, ELISA and WB to detect anti- L. infantum antibodies in feline serum samples obtained from endemic ( n  = 76) and non-endemic ( n  = 64) areas and from cats affected by feline leishmaniosis ( n  = 21) by a Bayesian approach without a gold standard. Methods Cut-offs were set at 80 titre for IFAT and 40 ELISA units for ELISA. WB was considered positive in presence of at least a 18 KDa band. Statistical analysis was performed through a written routine with MATLAB software in the Bayesian framework. The latent data and observations from the joint posterior were simulated in the Bayesian approach by an iterative Markov Chain Monte Carlo technique using the Gibbs sampler for estimating sensitivity and specificity of the three tests. Results The median seroprevalence in the sample used for evaluating the performance of tests was estimated at 0.27 [credible interval (CI) = 0.20–0.34]. The median sensitivity of the three different methods was 0.97 (CI: 0.86–1.00), 0.75 (CI: 0.61–0.87) and 0.70 (CI: 0.56–0.83) for WB, IFAT and ELISA, respectively. Median specificity reached 0.99 (CI: 0.96–1.00) with WB, 0.97 (CI: 0.93–0.99) with IFAT and 0.98 (CI: 0.94–1.00) with ELISA. IFAT was more sensitive than ELISA (75 vs 70%) for the detection of subclinical infection while ELISA was better for diagnosing clinical leishmaniosis when compared with IFAT (98 vs 97%). Conclusions The overall performance of all serological techniques was good and the most accurate test for anti- Leishmania antibody detection in feline serum samples was WB.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V
• Subject: 12th Symposium on Companion Vector-borne Diseases (CVBD) / Animal biology / Animals / Antibodies / Antibodies, Protozoan - blood / antibody detection / Antigen-antibody reactions / Bayes Theorem / Bayesian analysis / Bayesian theory / Biomedical and Life Sciences / Biomedicine / blood serum / Blotting, Western - methods / Blotting, Western - standards / Cat Diseases - diagnosis / Cat Diseases - immunology / Cats / Computer simulation / computer software / Diagnosis / Diagnostic systems / Diseases / ELISA / Entomology / enzyme-linked immunosorbent assay / Enzyme-Linked Immunosorbent Assay - methods / Enzyme-Linked Immunosorbent Assay - standards / Epidemiology / Female / Fluorescent Antibody Technique, Indirect - methods / Fluorescent Antibody Technique, Indirect - standards / Genetic aspects / Immunoglobulin G - blood / Immunoglobulins / Immunology / Infections / Infectious Diseases / Innovations / Laboratories / Leishmania / Leishmania infantum - immunology / Leishmaniasis / Leishmaniasis, Visceral - diagnosis / Leishmaniasis, Visceral - immunology / Leishmaniasis, Visceral - veterinary / Life Sciences / Male / Markov chain / Markov chains / Methods / Microbiology and Parasitology / Molecular diagnostic techniques / Monte Carlo method / Monte Carlo simulation / Observations / Parasitic diseases / Parasitology / Public health / Reference Standards / Sensitivity / Sensitivity and Specificity / Seroepidemiologic Studies / Serology / seroprevalence / Statistical analysis / Statistical methods / Tropical Medicine / Veterinary medicine and animal Health / Veterinary Medicine/Veterinary Science / Virology / Western blotting