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Overview of Neascus spp. ( Diplostomatidae ). Paul Schiller. Background. Neascus is a digenean trematode that most often infects centrarchid , & cyprinid fish species, some salmonids as juveniles ( FW ) Parasite has three stages (egg, larvae, & adult)
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Overview of Neascus spp. (Diplostomatidae) Paul Schiller
Background • Neascus is a digeneantrematode that most often infects centrarchid, & cyprinid fish species, some salmonidsas juveniles (FW) • Parasite has three stages (egg, larvae, & adult) • Also known as black spot disease • Wide distribution-N.America
Hosts Neascus spp. has complex life cycle that begins as an egg immersed in water • Forms juvenile larvae that uses gastropodamolluscs as a host (miracidium) • Fish are intermediate host (metacercariae) • Piscivorous birds become infected Cycle begins again after infected bird feces reach water
Life Cycle Final host
Impacts on fish • Larval form “burrows” into the skin and tissue. • Often not harmful to fish, except when fluke is in high densities, or near vital organs • Immune response creates the cyst that forms around invading fluke Neascus cyst on skin Encysted metacercariae
Impacts cont. • Sportfishing industry prefers “natural fish” • License sales • Shallow, warmer, eutrophic water bodies more susceptible to infestation
Management • Preventing introduction to water sources • Early hatchery operations enclosed • Baitfish industry and spread of minnows • Most current research into more dangerous metacercarciae
Potential Risk • Not harmful to humans if not cooked properly • Can be harmful to gastrointestinal tract if not cooked • Spread of live fish and carcasses is vector for disease spread • Wild adult fish are adaptable, and may be a cryptic advantage
Literature cited • Zimmermann, M., & Ingold, D. J. (2008). Parasite loads in three sunfish species (Lepomis sp.) on reclaimed mine ponds in Southeastern Ohio. Ohio Journal of Science, 108(1), A-22 • Dechiar, Alex (2011). Parasites of fish from Lake of the Woods, Ontario. Journal of the Fisheries Research Board of Canada, 1972, 29(3): 275-283, 10.1139/f72-046