Discovery of three novel coccidian parasites infecting California sea lions (Zalophus Californianus), with evidence of sexual replication and interspecies pathogenicity

Kathleen M. Colegrove, Michael E. Grigg, Daphne Carlson-Bremer, Robin H. Miller, Frances M D Gulland, David J P Ferguson, Daniel Rejmanek, Bradd C. Barr, Robert Nordhausen, Ann C. Melli, Patricia A Conrad

Research output: Contribution to journalArticle

9 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)868-877
Number of pages10
JournalJournal of Parasitology
Volume97
Issue number5
DOIs
StatePublished - Oct 2011

ASJC Scopus subject areas

  • Parasitology
  • Ecology, Evolution, Behavior and Systematics

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    Colegrove, K. M., Grigg, M. E., Carlson-Bremer, D., Miller, R. H., Gulland, F. M. D., Ferguson, D. J. P., Rejmanek, D., Barr, B. C., Nordhausen, R., Melli, A. C., & Conrad, P. A. (2011). Discovery of three novel coccidian parasites infecting California sea lions (Zalophus Californianus), with evidence of sexual replication and interspecies pathogenicity. Journal of Parasitology, 97(5), 868-877. https://doi.org/10.1645/GE-2756.1