On Mitten Crabs and Lung Flukes

Parasitology textbooks have long reported that grapsid crabs in the genus Eriocheir, commonly known as mitten crabs, are important second intermediate hosts of the Oriental Lung Fluke, Paragonimtrs westermani, along with several other crab'and crayfish species in Asia (e.g., Hegner and others 1929; Chandler and Read 196 1 ; Muller 1975; Cheng 1986; Smyth 1994). Epidemiologic reviews have specifically noted the Chinese Mitten Crab, E. sinensis, as an important source of human infection in China and Korea (Yokogawa 1965,1974; Miyazaki 1974; Choi 1990). Many of these texts include a diagram of the lung flukes' life cycle, often with a drawing of a mitten crab host, to illustrate the passage of digenetic trematodes through multiple host species (e.g., Lapage 1963, p. 154; Miyazaki 1974, p. 104; Kim 1984, p. 1 18 1). Recently, however, some Chinese fisheries experts-including Prof. Zhao, director of the Anhui Weiqing Aquatic Products Company, and Prof. Zhang (retired) of the Shanghai Fishery Research Institute-have said that this commonly-reported association of lung,flukes with mitten crabs is incorrect. According to these experts, l? westermani does not occur in E. sinensis and the true intermediate hosts of the lung fluke are various potamid crabs commonly known as creelc crabs (Hymanson and others 1999; Wang and Hess 2002). Wang and Hess (2002) suggest that an old translation error may have resulted in a misstatement of the fluke's crab host in western literature, which was then copied from paper to paper. To clarify the matter they recommend examining the early papers describing the lung fluke to determine if there were translation,errors, and comparing the range of infection in humans with the distribution of mitten crabs and crielc crabs.