In situ collected small intestinal mucosal swabs as alternative analytes to diagnose Echinococcus multilocularis infection in its definitive hosts by real-time polymerase chain reaction

Abstract

The cestode Echinococcus multilocularis parasitizes small intestines of carnivores such as foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) as definitive hosts and represents an important zoonotic threat. This study aimed to determine whether E. multilocularis DNA detection methods by real-time PCR involving easy-to-collect sample types, such as intestinal swabs could represent alternatives to traditional parasitological techniques. Three analytes from foxes and raccoon dogs were tested. i. Swabs taken immediately during necropsy (in situ) from the small intestinal mucosa (FastMucSwab), ii. swabs from scraped-off small intestinal mucosa (IsolMucSwab), collected for the sedimentation-counting-technique (SCT) and for comparative reasons iii. feces from the Ampulla recti. Only minor differences in E. multilocularis DNA detection, independent of sample type, were observed. High levels of concordance between PCR results were noted in the comparison of results on FastMucSwabs, IsolMucSwabs or feces. The agreement between FastMucSwab and IsolMucSwab was excellent (Kappa 0.86 [95 % CI: 0.79-0.92]). If inconclusive PCR results were excluded, PCR on FastMucSwabs had a diagnostic sensitivity of 92.7 % (95 % CI: 83.0–97.3 %) and a specificity of 91.5 % (95 % CI: 88.4–93.9 %) relative to SCT. Compared with SCT, Feces real-time PCR had a diagnostic sensitivity of 82.8 % (95 % CI: 63.5–93.5 %) and a specificity of 90.9 % (95 % CI: 81.4–95.9 %). Segmental swabbing had no diagnostic advantages. Overall, there was evidence that the DNA detection methods used here had a higher diagnostic sensitivity than SCT did. Results suggest that simple alternative methods, such as PCR on FastMucSwabs represent an efficient tool for performing larger-scale epidemiological studies.