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Diseases of Aquatic Organisms

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DAO 131:87-94 (2018)  -  DOI: https://doi.org/10.3354/dao03291

Brucella pinnipedialis in lungworms Parafilaroides sp. and Pacific harbor seals Phoca vitulina richardsi: proposed pathogenesis

Jack Rhyan1,*, Mike Garner2, Terry Spraker3, Dyanna Lambourn4, Norman Cheville5

1United States Department of Agriculture, National Wildlife Research Center, Fort Collins, CO 80521, USA
2Northwest ZooPath, Monroe, WA 98272, USA
3Colorado State University Diagnostic Laboratory, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80526, USA
4Washington Department of Fish and Wildlife, Marine Mammal Investigations, Lakewood, WA 98498, USA
5Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA
*Corresponding author:

ABSTRACT: Brucella spp. were first isolated from marine mammals in 1994 and since have been described in numerous pinniped and cetacean species with nearly global distribution. Microscopic, electron microscopic, or culture results have shown lungworms in harbor seals to be infected with brucellae, suggesting that the lungworms may serve a role in this infection. In this study, we reviewed archived and more recent case material from 5 Pacific harbor seals from Washington State (USA) with evidence of B. pinnipedialis infection in the lungworm Parafilaroides sp. Twenty-two sections of lung containing approximately 220 Parafilaroides sp., stained with an immunohistochemical technique using antibody to B. abortus, showed approximately 80 (36%) infected nematodes. A few brucellae were also present in lung parenchyma in proximity to nematodes. Infection was present in the first- and fourth-stage larvae in the seal lung and intestines, as well as in the male and female reproductive organs of adult nematodes. Infected sperm deposits in the nematode uterus were suggestive of venereal transmission between lungworms. Massive infection of some degenerate adult lungworms and evidence of degeneration of some developing larvae in utero were observed. Based on these observations, we suggest that Parafilaroides sp., rather than the Pacific harbor seal Phoca vitulina richardsi, is the preferred host of B. pinnipedialis infection.


KEY WORDS: Brucella · B. pinnipedialis · Harbor seals · Lungworm · Parafilaroides · Pathogenesis · Phoca vitulina · Immunohistochemistry


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Cite this article as: Rhyan J, Garner M, Spraker T, Lambourn D, Cheville N (2018) Brucella pinnipedialis in lungworms Parafilaroides sp. and Pacific harbor seals Phoca vitulina richardsi: proposed pathogenesis. Dis Aquat Org 131:87-94. https://doi.org/10.3354/dao03291

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