Improved multiplex PCR assay for host species identification from fecal samples in Echinococcus multilocularis...

Echinococcus multilocularis, which causes alveolar echinococcosis, can infect a wide range of hosts. Increasing interactions among wildlife, domestic animals, and humans may enhance the transmission risk in endemic areas. Surveillance of E. multilocularis in definitive hosts has relied on the post-mortem examination of the small intestine using the sedimentation and counting technique, with a recent shift toward non-invasive methods targeting fecal samples. However, host identification based solely on visual inspection of feces is often unreliable. Existing PCR-based methods are limited by complexity, low resolution, or a narrow range of target species. In this study, we developed a multiplex PCR assay targeting the mitochondrial 16S rRNA gene for simultaneous identification of 10 host species and evaluated its performance against a reference PCR assay. A total of 114 fecal samples, visually considered as fox-derived, were collected from roadsides in three areas in Hokkaido, Japan. Animal species were successfully identified in 106 samples (93.0%) using the newly developed multiplex PCR assay. Overall, foxes were the most common (74.6%), followed by cats (12.3%), dogs (5.3%), and raccoons (1.8%). The new assay showed almost perfect agreement with the reference method (κ = 0.94; 95% CI: 0.87-1; n = 114). Molecular identification revealed that 20.6% of samples were not derived from foxes, indicating that visual inspection is prone to identification errors. PCR screening detected E. multilocularis DNA in 34.2% of all samples. The positivity rate was 41.2% in foxes and 28.6% in cats. These findings highlight the importance of accurate host identification for reliable E. multilocularis surveillance. The developed multiplex PCR assay provides a rapid and robust approach to improve the accuracy of epidemiological surveillance and support effective control strategies.