title: Detection of spirorchiid trematodes in gastropod tissues by polymerase chain reaction: preliminary identification of an intermediate host of Learedius learedi.
abstract: Marine spirorchiid trematodes are associated with morbidity and mortality in sea turtles worldwide. The intermediate hosts remain unknown, and discovery efforts are hindered by the large number and great diversity of potential hosts within sea turtle habitats, as well the potential for low prevalence and overdispersion. A high-throughput DNA extraction and polymerase chain reaction-based method was developed to detect the internal transcribed spacer 2 (ITS2) region of the ribosomal gene of 2 spirorchiid genera, Learedius and Hapalotrema , within pooled samples of gastropod tissues. A model system consisting of freshwater snail ( Pomacea bridgesii ) tissues and DNA extracts spiked with adult Learedius learedi and known quantities of spirorchiid DNA was used to develop and test the technique. Threshold of detection was found to be equivalent to an early prepatent infection within 1.5 g of gastropod tissue. This technique was used to screen approximately 25 species of marine gastropods at a captive facility where green turtles ( Chelonia mydas ) become infected by L. learedi . The parasite was detected in a sample of knobby keyhole limpet ( Fissurella nodosa ), thus providing the first evidence of an intermediate host for a marine spirorchiid trematode. This technique has many potential applications in trematode life cycle discovery studies.
authors.affiliation: College of Veterinary Medicine, University of Florida, P.O. Box 100136, Gainesville, FL 32610, USA. stacyb@vetmed.ufl.edu
authors.forename: Brian A
authors.initials: BA
authors.lastname: Stacy
authors.forename: Thomas
authors.initials: T
authors.lastname: Frankovich
authors.forename: Ellis
authors.initials: E
authors.lastname: Greiner
authors.forename: A Rick
authors.initials: AR
authors.lastname: Alleman
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Herbst
authors.forename: Paul
authors.initials: P
authors.lastname: Klein
authors.forename: Alan
authors.initials: A
authors.lastname: Bolten
authors.forename: Antoinette
authors.initials: A
authors.lastname: McIntosh
authors.forename: Elliott R
authors.initials: ER
authors.lastname: Jacobson
mesh_terms: D000818:Animals; D018509:DNA, Helminth / Q000302:isolation & purification*; D049851:Gastropoda / Q000469:parasitology*; D016133:Polymerase Chain Reaction / Q000662:veterinary*; D014200:Trematoda / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D018509:DNA, Helminth