First identification of adult Mesocestoides vogae in a domestic dog in Japan.

In recent years, several cases of Mesocestoides vogae infection have been reported in domestic dogs in Japan. These cases typically involved the detection of tetrathyridia and segmented worms with immature proglottids, but not mature adults with gravid proglottids. In this study, mature and gravid proglottids of M. vogae were identified in a domestic dog from Niigata Prefecture. Morphological examination confirmed the parasite to be a Mesocestoides species based on the presence of a well-developed parauterine organ. Further molecular analysis identified the parasite as M. vogae. This is the first report of gravid proglottids of M. vogae in a domestic dog, suggesting the potential role of dogs as definitive hosts in the transmission cycle of this parasite.