Case Report: Neurological and pulmonary angiostrongylosis in a Ryukyu long-furred rat (Diplothrix legata) on Amami-Oshima Island, Japan

A Ryukyu long-furred rat ( Diplothrix legata ) rescued on Amami-Oshima Island, located in the southwestern Japan, exhibited neurological signs, including nystagmus and ataxia, and died six days after supportive treatment. Gross and histopathological examinations revealed nematodes in the brain, lungs, and heart. In the meninges, immature worm sections were associated with marked inflammatory thickening. Pulmonary lesions included adult worms, eggs, and larvae accompanied by hemorrhage, edema, thrombosis, and extensive necrosis with concurrent Aspergillus infection. Mitochondrial cytochrome c oxidase 1 sequences obtained from the nematodes identified the ac1 lineage of Angiostrongylus cantonensis , a haplotype previously reported from mainland Japan and Amami-Oshima Island, but distinct from the lineage common on the neighboring islands of Okinawajima and Tokunoshima. This case supports the occurrence of angiostrongylosis in the Ryukyu long-furred rat and suggests that this species may manifest both neurological and respiratory disease manifestations. Further epidemiological investigations targeting invasive rodents of the genus Rattus , intermediate host, namely terrestrial gastropods (e.g., snails and slugs), and potential paratenic hosts (e.g., amphibians and reptiles), are warranted to clarify the transmission dynamics of A. cantonensis within the Amami Islands and to assess its potential impact on this endangered endemic rodent.