Coccidiosis in green turtles (Chelonia Mydas) in Australia: pathogenesis, spatial and temporal distribution, and climate-related determinants of disease outbreaks

Ban de Gouvea Pedroso, Silvia, Phalen, David N., Terkildsen, Michael, Blyde, David, March, Duane T., Gordon, Anita N., Chapman, Phoebe A., Mills, Paul C., Owen, Helen, Gillett, Amber, Lloyd, Hannah B., Ross, Geoffrey A., Hall, Jane, Scott, Jennifer, Ariel, Ellen, Yang, Rongchang, and Rose, Karrie A. (2020) Coccidiosis in green turtles (Chelonia Mydas) in Australia: pathogenesis, spatial and temporal distribution, and climate-related determinants of disease outbreaks. Journal of Wildlife Diseases, 56 (2). pp. 359-371.

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Abstract

An epizootic of coccidiosis in free-ranging green turtles (Chelonia mydas) occurred in Australia in 1991 and the parasites were thought to be Caryospora cheloniae. Recurring outbreaks over an increased geographic range followed. We used medical records and temporal and spatial data of turtles diagnosed with coccidiosis between 1991 and 2014 to characterize the disease and factors associated with outbreaks. Most affected animals were subadults or older. Neurologic signs with intralesional cerebral coccidia were observed. Coccidia associated with inflammation and necrosis were predominantly found in the intestine, brain, kidney, and thyroid. Cases occurred in the spring and summer. Three major outbreaks (1991, 2002, and 2014) were concentrated in Port Stephens, New South Wales (NSW) and Moreton Bay, Queensland (QLD), but cases occurred as far south as Sydney, NSW. Coccidiosis cases were more likely during, or 1 mo prior to, El Nin˜ o–like events. Molecular characterization of the 18S rRNA locus of coccidia from tissues of 10 green turtles collected in 2002 and 2004 in Port Stevens and Sydney imply that they were Schellackia-like organisms. Two sequences were identified. The genotype 3 sequence was most common (in eight of 10 turtles), with 98.8% similarity to the 18S sequence of Schellackia orientalis. The Genotype 4 sequence was less common (in two of 10 turtles) with 99.7% similarity to the 18S sequence of the most common genotype (Genotype 1) detected in turtles from the 2014 Moreton Bay outbreak. Our study will help with the identification and management of future outbreaks and provide tools for identification of additional disease patterns in green turtles.

Item ID: 64648
Item Type: Article (Research - C1)
ISSN: 1943-3700
Keywords: Caryospora, Chelonia mydas, coccidiosis, green turtle, pathogenesis, Schellackia, spatial distribution, temporal distribution
Copyright Information: © Wildlife Disease Association 2020.
Funders: New South Wales Office of Environment and Heritage, Taronga Conservation Society, Sydney School of Veterinary Sciences
Date Deposited: 26 Oct 2020 21:34
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0707 Veterinary Sciences > 070708 Veterinary Parasitology @ 100%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960402 Control of Animal Pests, Diseases and Exotic Species in Coastal and Estuarine Environments @ 100%
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