Molecular phylogenetic analysis of Echinococcus multilocularis from horses raised in Canada or Japan, using mitochondrial cytochrome b gene-targeted PCR.

Alveolar echinococcosis is a zoonotic disease caused by a larval-stage Echinococcus multilocularis infection. Geographical haplotyping targeting the parasite's mitochondrial cytochrome b (cob) gene has been reported for isolates from definitive and intermediate hosts (wild canids and rodents); however, there are limited reports on strain typing for the dead-end host, the horse, which could act as a sentinel for E. multilocularis. Accordingly, we investigated the diversity of E. multilocularis in isolates obtained from slaughtered Japanese and Canadian horses originating from the Iburi and Hidaka regions in Hokkaido and from Alberta, respectively, with PCR and haplogroup analyses targeting cob gene sequences obtained. Seventy horses were diagnosed with alveolar echinococcosis based on histopathology and cob-gene PCR testing. The E. multilocularis detected in these horses was classified as either an Asian (for Hokkaido-raised horses) or a European (for Alberta-raised horses) haplogroup, based on the obtained cob-gene sequence analysis. In addition, haplotype network analysis revealed that E. multilocularis isolated from Hokkaido-raised horses is highly homologous to Kazakhstan isolates, and E. multilocularis isolated from Alberta-raised horses is highly homologous to Austrian isolates. The results of this study suggest that cob-gene-targeted PCR analysis could be useful for the geographical genetic characterization of E. multilocularis isolated from horses.