Pseudodactylogyrus anguillae and Pseudodactylogyrus bini

Parasitic monogeneans, Pseudodactylogyrus anguillae and Pseudodactylogyrus bini, cause severe disease in aquaculture of European eel (Anguilla anguilla) and Japanese eel (Anguilla japonica). It is hypothesized that the two monogeneans have originated from parasites in Pacific eels and spread to Europe via the fish trade. These monogeneans are hermaphroditic and oviparous with a temperature-dependent life cycle comprising eggs, oncomiracidia, juveniles and adults. Mechanical and chemical stimulations of host gills by opisthaptoral hard parts and parasite feeding elicit hyperplasia, lamellar fusion and clubbing of gill filaments, which reduce the respiratory surface and oxygen uptake. Biosecurity measures are necessary to prevent introduction of parasites, but if parasites are in a facility control measures include filtration of water using fine filters to remove eggs and larvae. Bath treatments of infected eels using praziquantel or mebendazole reduce infection level and eel mortality. European eels develop acquired immunity, but no vaccines are available.