title: Molecular Characterization of Coccidia Associated with an Epizootic in Green Sea Turtles (Chelonia mydas) in South East Queensland, Australia.
abstract: In the spring of 2014, mass mortalities among wild green sea turtles occurred off the coast of south-east Queensland, Australia. The suspected causative agent was Caryospora cheloniae, an eimeriid coccidian implicated in previous epizootics. Necropsies were undertaken on a subset of 11 dead turtles, with subsequent histopathology and molecular analyses. All turtles returned positive PCR results for coccidial infection in various tissues; these included the brain, gastrointestinal tract, lung, kidney and thyroid. Granulomatous encephalitis was consistently observed, as well as enteritis and, less frequently, thyroiditis and nephritis. Sequencing and phylogenetic analyses indicated the presence of two distinct coccidian genotypes, presumably separate species-one associated with the brain, gastrointestinal tract and lung, and the second with the thyroid and kidney. Maximum likelihood and Bayesian inference analyses placed the first genotype closest to the lankesterellid genus Schellackia, rather than in the Eimeriidae, while the second was paraphyletic to the eimeriids. Presence of coccidial stages in extra-intestinal tissues of the primary host raises questions about the potential presence of intermediate or paratenic hosts within the life cycles, as well as their current placement relative to the genus Caryospora. This study represents the first genetic characterization of this emerging disease agent in green sea turtles, an endangered species, and has relevance for life-cycle elucidation and future development of diagnostics.
authors.affiliation: Veterinary-Marine Animal Research Teaching and Investigation Unit, School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.
authors.forename: Phoebe A
authors.initials: PA
authors.lastname: Chapman
authors.affiliation: Veterinary-Marine Animal Research Teaching and Investigation Unit, School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.
authors.forename: Helen
authors.initials: H
authors.lastname: Owen
authors.affiliation: Veterinary-Marine Animal Research Teaching and Investigation Unit, School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.|School of Forest Resources and Conservation, University of Florida, The Florida Aquarium's Center for Conservation, Apollo Beach, Florida, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Flint
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Traub
authors.affiliation: School of Biological Science, University of Queensland, St Lucia, Queensland, Australia.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Cribb
authors.affiliation: Veterinary-Marine Animal Research Teaching and Investigation Unit, School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Mills
mesh_terms: D000818:Animals; D001315:Australia; D001499:Bayes Theorem; D001921:Brain / Q000469:parasitology; D003044:Coccidia / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity*; D007422:Intestines / Q000469:parasitology; D007668:Kidney / Q000469:parasitology; D010802:Phylogeny; D011793:Queensland; D013961:Thyroid Gland / Q000503:physiopathology; D014426:Turtles