DAO 81:5-11 (2008)  -  DOI: https://doi.org/10.3354/dao01905

Contribution to the DAO Special 'Marine vertebrate zoonoses'

Prevalence and characterization of Salmonella spp. among marine animals in the Channel Islands, California

R. A. Stoddard1,2,*, R. L. DeLong3, B. A. Byrne2, S. Jang2, Frances M. D. Gulland1

1The Marine Mammal Center, 1065 Fort Cronkhite, Sausalito, California 94965, USA
2Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA
3National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, Bldg. 4,
7600 Sand Point Way NE, Seattle, Washington 96115, USA

ABSTRACT: Salmonella enterica is a zoonotic pathogen that has been isolated from free-ranging marine mammals throughout the world, with animals in the Channel Islands of California (USA) showing the highest prevalence. The goal of this study was to determine prevalence, antimicrobial sensitivity and genetic similarity using pulsed-field gel electrophoresis (PFGE) of Salmonella in several non-domestic animal species on San Miguel and San Nicolas Islands. Fecal samples were collected from 90 California sea lion Zalophus californianus pups, 30 northern elephant seal Mirounga angustirostris pups and 87 western gulls Larus occidentalis in the Channel Islands and 59 adult male sea lions in Puget Sound, WA (USA). Salmonella were isolated, identified and serotyped, followed by antimicrobial susceptibility testing and PFGE. Of the California sea lion pups that were sampled on the islands, 21% (n = 19) were positive for Salmonella, whereas no adults males in Puget Sound were positive. Of the northern elephant seal pups sampled, 87% (n = 26) were harboring Salmonella. Only 9% (n = 8) of western gulls were shedding Salmonella, with one of these gulls harboring the only antimicrobial resistant isolate. The serotypes found in these animals were Enteritidis, Montevideo, Newport, Reading, and Saint Paul. The only serotype that showed variation on PFGE was Newport. The pinnipeds of the Channel Islands harbor Salmonella at a higher prevalence than pinnipeds from other geographic areas observed in previous studies. Researchers and veterinarians should exercise increased caution when working with these animals due to the zoonotic potential of Salmonella.


KEY WORDS: Salmonella enterica · Channel Islands · California sea lions · Northern elephant seals · Western gulls · Marine animals


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Cite this article as: Stoddard RA, DeLong RL, Byrne BA, Jang S, Gulland FM (2008) Prevalence and characterization of Salmonella spp. among marine animals in the Channel Islands, California. Dis Aquat Org 81:5-11. https://doi.org/10.3354/dao01905

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