Immunological and molecular tools for environmental surveillance of canine echinococcosis: Steps toward a sustainable diagnostic algorithm.

Abstract

Canine echinococcosis (CaEc) surveillance has evolved from necropsy and arecoline purgation to the detection of coproantigens (cELISA) and genomic copro-DNA (cPCR and cLAMP). Each technique has advantages and disadvantages regarding biosafety, ethics, and costs. In Argentina, there is no consensus on CaEc surveillance tools or their suitability for low- and medium-complexity laboratories. The aim of this work was to compare the performance of techniques with different targets for CaEc surveillance, including cELISA, nested cPCR, and two cLAMPEGSL (2.0 and 3.0). Environmental canine fecal samples (n = 127) from endemic areas were analyzed using the four methods. Overall, Positive and Negative Percent Agreement (OPA, PPA, NPA) were evaluated. Sensitivity and specificity of each technique, and general prevalence were estimated using a Bayesian latent class model (BLCA). Both cLAMPEGSL3.0 and cPCR techniques showed higher OPA and NPA values than the cELISA, a validated method with very high NPV. Sensitivity estimates for each technique were: cELISA: 78.8 % (95 % CI: 56-94 %); cPCR 87.9 % (66-98 %); cLAMPEGSL2.0 65.6 % (29-96 %) and cLAMPEGSL3.0 86.3 % (50-99 %). While specificities estimates were: cELISA 55.7 % (46-66 %); cPCR 64.7 % (55-74 %); cLAMPEGSL2.0 57.9 % (47-68 %) and cLAMPEGSL3.0 62.4 % (52-73 %). The estimated general prevalence of CaEc was 13.1 % (9-18 %). This is the first study conducted in Argentina to compare the performance of four techniques with different targets for CaEc surveillance. Sensitivity and specificity of each technique, and general prevalence were estimated using a Bayesian Latent Class Analysis (BLCA) model. Using a BLCA model, both cPCR and cLAMPEGSL3.0 showed the best estimated sensitivity and specificity values. These results provide control programs with molecular tools suitable for use in medium- and low-complexity laboratories.