Echinostoma revolutum: Metacercariae inFilopaludinaSnails from Nam Dinh Province, Vietnam, and Adults from Experimental Hamsters

Echinostomes ( = family Echinostomatidae) are intestinal flukes of birds and mammals, including humans [1,2].In heavy infections, they can cause mucosal ulceration, bleeding, and severe inflammation in human patients.To date, 20 species of zoonotic echinostomes belonging to 9 genera have been discovered worldwide (Echinostoma, Echinochasmus, Acanthopary phium, Artyfechinostomum, Echinoparyphium, Episthmium, Him asthla, Hypoderaeum, and Isthmiophora) [1].Among them, Echi nostoma is the most important and 7 zoonotic species of Echi nostoma are known; Echinostoma revolutum, E. angustitestis, E. ci netorchis, E. echinatum, E. hortense, E. ilocanum, and E. macror chis [1].E. revolutum (Froelich, 1802) Looss, 1899 was the first echinostome species described in the literature [1].It was first discovered as an intestinal fluke of ducks but is now known to in-fect a variety of avian and mammalian species, including geese, muskrats, and humans [1-3].E. revolutum is found worldwide, including Asia, Europe, Africa, Australia, New Zealand, and the Americas [1].In Asia, E. revolutum has been reported from China, Taiwan, Korea, Japan, Indonesia, Malaysia, Thailand, India, Russia, and Cambodia [1-6].Vietnam was among the list of countries where E. revolutum was distributed [6].However, it was based upon a suggestion on the presence of the larval stage, Cercaria spinifera [7].No other detailed information about this echinostome in Vietnam is available.In the present study, we purchased Filopaludina sp.snails from a local market in Nam Dinh Province, Vietnam and examined them for the presence of echinostome metacercariae.We detected metacercariae and identified them as E. revolutum through recovery of adult flukes from experimental hamsters.Filopaludina sp.snails (Fig. 1) were purchased from a local market in Nam Dinh Province, Vietnam in April 2005 and transferred to our laboratory (Gyeongsang National University, Jinju, the Republic of Korea) on ice.They (n= 30) were divided into 6 groups, crushed with their shells using a mortar and pestle, and digested for 2 hr in pepsin-HCl solution.A total of