title: Discovery of three novel coccidian parasites infecting California sea lions (Zalophus californianus), with evidence of sexual replication and interspecies pathogenicity.
abstract: Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA sequences with closest homology to Neospora sp. (80%); these novel sequences were referred to as belonging to coccidian parasites "A," "B," and "C." Subsequent molecular analyses completed on a neonatal harbor seal (Phoca vitulina) with protozoal lymphadenitis, hepatitis, myocarditis, and encephalitis showed that it was infected with a coccidian parasite bearing the "C" sequence type. Our results indicate that sea lions likely serve as definitive hosts for 3 newly described coccidian parasites, at least 1 of which is pathogenic in a marine mammal intermediate host species.
authors.affiliation: Zoological Pathology Program, College of Veterinary Medicine at Urbana-Champaign, Loyola University Medical Center, 2160 South First Avenue, Maywood, Illinois 60153, USA. kcolegrove@lumc.edu
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Colegrove
authors.forename: Michael E
authors.initials: ME
authors.lastname: Grigg
authors.forename: Daphne
authors.initials: D
authors.lastname: Carlson-Bremer
authors.forename: Robin H
authors.initials: RH
authors.lastname: Miller
authors.forename: Frances M D
authors.initials: FM
authors.lastname: Gulland
authors.forename: David J P
authors.initials: DJ
authors.lastname: Ferguson
authors.forename: Daniel
authors.initials: D
authors.lastname: Rejmanek
authors.forename: Bradd C
authors.initials: BC
authors.lastname: Barr
authors.forename: Robert
authors.initials: R
authors.lastname: Nordhausen
authors.forename: Ann C
authors.initials: AC
authors.lastname: Melli
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Conrad
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D003048:Coccidiosis / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D016054:DNA, Protozoan / Q000737:chemistry / Q000302:isolation & purification; D020895:Enterocytes / Q000469:parasitology / Q000648:ultrastructure; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D007421:Intestine, Small / Q000469:parasitology / Q000473:pathology; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D008969:Molecular Sequence Data; D018688:Neospora / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D046049:Phoca / Q000469:parasitology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012522:Sarcocystis / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D012523:Sarcocystosis / Q000469:parasitology / Q000473:pathology / Q000662:veterinary; D046070:Sea Lions / Q000469:parasitology*; D016415:Sequence Alignment / Q000662:veterinary; D014122:Toxoplasma / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D014124:Toxoplasmosis, Animal / Q000469:parasitology / Q000473:pathology
chemical_list: D000913:Antibodies, Protozoan; D016054:DNA, Protozoan