DNA-based identification of a hepatic trematode in an elk calf.

TitleDNA-based identification of a hepatic trematode in an elk calf.
Publication TypeJournal Article
Year of Publication2007
AuthorsBildfell RJ, Whipps CM, Gillin CM, Kent ML
JournalJournal of wildlife diseases
Volume43
Issue4
Pagination762-9
Date Published2007 Oct
ISSN0090-3558
KeywordsAnimals, Animals, Newborn, Animals, Wild, Deer, DNA, Helminth, Fasciola, Fasciola hepatica, Fascioliasis, Fatal Outcome, Male, Oregon, Phylogeny, Sequence Analysis, DNA
Abstract

Liver fluke infection was identified as a probable cause of clinical disease in an approximately 6-mo-old elk (Cervus elaphus) in coastal Oregon. Clinical pathology and necropsy findings are described. The alcohol-fixed flukes that were submitted for identification were similar in size to Fasciola hepatica, but their shape resembled Fascioloides magna in that they lacked a distinctive anterior cone. A few structures consistent with the eggs of F. magna were observed in liver lesions, suggesting that at least some of the worms were sexually maturing. Due to difficulties in morphologic identification associated with improper fixation technique, DNA analysis was used to compare small subunit (SSU) and internal transcribed spacer 2 ribosomal RNA gene sequences of the recovered parasites with those of F. hepatica and F. magna, confirming these small, but sexually mature flukes were F. magna. This is the first publication of the SSU gene sequence for F. magna. Phylogenetic analysis showed that it is related to, but is an outlier, to the genus Fasciola. Due to the high mortality rate associated with this disease outbreak, the overall significance of trematodiasis in the herd is unclear.

Alternate JournalJ. Wildl. Dis.