First Case of Echinococcus multilocularis Infection in a Zoo-Housed Flying Squirrel (Pteromys volans orii)

A 33 month-old male flying squirrel kept in a zoo developed progressive dyspnea and died. Macroscopically, the liver and lung were enlarged with numerous nodular vesicles. Histologically, these organs were replaced by numerous collapsed vesicles demarcated by fibrous tissues. The cysts lined by a cellular, germinal layer contained numerous brood capsules with abundant production of well-developed protoscolices. Protoscolices were about 80-100 mu m in diameter, and had hooks being visible as refractive structures. This zoo locates in the east of Hokkaido where is an endemic area of Echinococcus multilocularis infection. From epidemiology and pathological findings, this animal was diagnosed as E. multilocularis infection. This report describes the pathology of the first case of E. multilocularis infection in a flying squirrel.