First record of Brachylaima asakawai (Trematoda: Brachylaimidae) in a carnivore host, the red fox (Vulpes vulpes schrencki).

Accumulating information on the relationship between hosts and parasites is important to understand their life cycle. Nine Brachylaima spp. species exist in Japan, but their life cycles are not fully understood, partly because of their low prevalence in their definitive hosts. In this study, 23 trematodes, thought to belong to the genus Brachylyma were found in the small intestine of the red fox (Vulpes vulpes schrencki) in Hokkaido, Japan. We analyzed these trematodes using morphological and molecular methods. Morphological analysis showed that the trematodes had the same features as Brachylaima asakawai. We extracted DNA from the trematodes and amplified the nuclear 28S ribosomal RNA (28S rDNA) and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes. The 28S rDNA and cox1 fragments were 100 % and 99.7 % identical to the B. asakawai, respectively. Previously, B. asakawai was detected only in rodents in Hokkaido; however, this study demonstrated that it is also a fox parasite. This is the second report of a definitive natural host for B. asakawai and the first record of the red fox being found as a new definitive host for B. asakawai. To fully understand the host preference and range of B. asakawai, it is essential to continuously survey various animals to understand the life cycle of B. asakawai completely.