title: Natural Heterobilharzia americana infection in horses in Texas.
abstract: The schistosome Heterobilharzia americana infects dogs, raccoons, and other mammals in the southeastern United States. Migration of eggs into the liver results in parasitic granulomas with varying degrees of fibrosis and inflammation. Recently, hepatic parasitic granulomas in horses were shown to be caused by H. americana infection. In the present study, samples of liver from 11 of 12 horses with hepatic granulomas identified at necropsy (n = 11) or surgical biopsy (n = 1) were used for DNA extraction, polymerase chain reaction amplification and sequencing using primers specific for a portion of the H. americana small subunit ribosomal RNA gene. A polymerase chain reaction amplicon of the correct size was produced from the extracted DNA in 8 of the 11 horses. Amplicons from 5 of the 8 positive horses were sequenced and had 100% identity with H. americana. In all but 2 of the 12 horses, Heterobilharzia was not responsible for the primary clinical disease, and the hepatic granulomas were considered an incidental finding.
authors.affiliation: Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA. wcorapi@cvm.tamu.edu
authors.forename: W V
authors.initials: WV
authors.lastname: Corapi
authors.forename: K F
authors.initials: KF
authors.lastname: Snowden
authors.forename: A
authors.initials: A
authors.lastname: Rodrigues
authors.forename: B F
authors.initials: BF
authors.lastname: Porter
authors.forename: M A
authors.initials: MA
authors.lastname: Buote
authors.forename: S M
authors.initials: SM
authors.lastname: Birch
authors.forename: N D
authors.initials: ND
authors.lastname: Jackson
authors.forename: K B
authors.initials: KB
authors.lastname: Eden
authors.forename: D B
authors.initials: DB
authors.lastname: Whitley
authors.forename: J
authors.initials: J
authors.lastname: Mansell
authors.forename: J F
authors.initials: JF
authors.lastname: Edwards
authors.forename: J
authors.initials: J
authors.lastname: Hardy
authors.forename: M K
authors.initials: MK
authors.lastname: Chaffin
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D006099:Granuloma / Q000469:parasitology / Q000473:pathology*; D006734:Horse Diseases / Q000469:parasitology* / Q000473:pathology; D006736:Horses; D008099:Liver / Q000469:parasitology / Q000473:pathology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012335:RNA, Ribosomal / Q000235:genetics; D012551:Schistosomatidae / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013781:Texas; D014201:Trematode Infections / Q000473:pathology / Q000662:veterinary*
chemical_list: D017931:DNA Primers; D012335:RNA, Ribosomal