Evaluation of fecal immunoassays for canine Echinococcus infection in China

Human echinococcosis is present worldwide but it is in China that disease prevalence is the highest. In western China, especially in the Tibetan Plateau, the burden of echinococcosis is the most important. Dogs are a major definitive host of Echinococcus and monitoring the presence of Echinococcus worms in dogs is therefore essential to efficiently control the disease. Detection kits based on three different technologies including sandwich ELISA, (indirect) ELISA, and gold immunodiffusion, are currently marketed and used in China. The objective of this work was to assess the efficacy of these kits, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine infection reflecting the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The results indicate that the performance is lower than expected, in particular in terms of sensitivity. The best results were obtained with the sandwich ELISA technology. The gold immunofiltration yielded the poorest results. In all cases, further development is needed to improve the performance of these kits which are key components for the control of echinococcosis.
Author summary Although present worldwide, human echinococcosis is at its highest prevalence in western China and particularly in the Tibetan Plateau. Controlling echinococcosis is a national priority and routine monitoring must be established. Dogs are the main infection source in China and surveying Echinococcus worms in dogs is therefore a research priority. Commercial detection kits are currently in use in China to monitor the presence of Echinococcus in dogs. The kits are based on three different technologies including sandwich ELISA with two monoclonal antibodies, (indirect) ELISA, and gold immunodiffusion. National survey programmes are essential for the control of echinococcosis and it is thus very important to assess the efficacy of these kits for the programmes. This work was therefore undertaken to assess efficacy of the kits, in particular with respect to sensitivity and specificity. Four fecal antigen detection kits for canine infection reflecting the three technologies were obtained from companies and tested in parallel on 220 fecal samples. The performance was lower than expected, in particular for their sensitivity which ranged between 51.5% and 83.9% with only two samples displaying a worm burden lower than 100. Three out of four kits showed non-specific cross-reactions with other parasites. The best results were obtained with the sandwich ELISA technology, whereas gold immunofiltration yielded the poorest results. However, in all cases, further development is strongly needed to improve the performance of these kits which are key components for the control of echinococcosis.