BRUCELLA PINNIPEDIALIS INFECTIONS IN PACIFIC HARBOR SEALS (PHOCA VITULINA RICHARDSI) FROM WASHINGTON STATE, USA Dyanna M. Lambourn, 1,9 Michael Garner, 2 Darla Ewalt, 3 Stephen Raverty, 4 Inga Sidor, 5,8 Steven J. Jeffries, 1 Jack Rhyan, 6 and Joseph K. Gaydos 7 1 Washington Department of Fish and Wildlife, Marine Mammal Investigations, 7801 Phillips Rd. S.W., Lakewood, Washington 98498, USA 2 Northwest ZooPath, 654 West Main, Monroe, Washington 98272, USA 3 National Veterinary Services Laboratories, 1920 Dayton Ave, Ames, Iowa 50010, USA 4 Animal Health Centre, British Columbia Ministry of Agriculture, 1767 Angus Campbell Road, Abbotsford, British Columbia V3G 2M3, Canada 5 Mystic Aquarium & Institute for Exploration, 55 Coogan Blvd., Mystic, Connecticut 06355, USA 6 National Wildlife Research, 4101 Laporte Ave., Fort Collins, Colorado 80521, USA 7 Wildlife Health Center–Orcas Island Office, UC Davis School of Veterinary Medicine, 942 Deer Harbor Rd., Eastsound, Washington 98245, USA 8 Current address: New Hampshire Veterinary Diagnostic Laboratory, University of New Hampshire, 129 Main St., Durham, New Hampshire 03824, USA 9 Corresponding author (email: dyanna.lambourn@dfw.wa.gov) ABSTRACT: In 1994 a novel Brucella sp., later named B. pinnipedialis, was identified in stranded harbor seals (Phoca vitulina). This Brucella sp. is a potential zoonotic pathogen and is capable of causing disease in domestic animals. Serologic, microbiologic, and pathologic data collected from live captured and stranded harbor seals were used to better describe the epizootiology of B. pinnipedialis in harbor seals from Washington State, USA, in 1994 through 2006. We found no sex predilection in harbor seal exposure or infection with B. pinnipedialis but noted a significant difference in prevalence among age classes, with weaned pups, yearlings, and subadults having highest exposure and infection. The most common postmortem finding in 26 Brucella-positive animals (culture and/or PCR) was verminous pneumonia due to Parafilaroides spp. or Otostrongulus circumlitus. Our data are consistent with exposure to B. pinnipedialis post-weaning, and it is likely that fish or invertebrates and possibly lungworms are involved in the transmission to harbor seals. Brucella pinnipedialis was cultured or detected by PCR from seal salivary gland, lung, urinary bladder, and feces, suggesting that wildlife professionals working with live, infected seals could be exposed to the bacterium via exposure to oral secretions, urine, or feces. Endangered sympatric wildlife species could be exposed to B. pinnipedialis via predation on infected seals or through a common marine fish or invertebrate prey item involved in its transmission. More work is required to elucidate further potential fish or invertebrates that could be involved in the transmission of B. pinnipedialis to harbor seals and better understand the potential risk they could pose to humans or sympatric endangered species who also consume these prey items. Key words: Brucella pinnipedialis, brucellosis, disease screening, harbor seal, marine, Phoca vitulina richardsi, zoonosis. INTRODUCTION In 1994 a novel Brucella was reported in harbor seals (Phoca vitulina), harbor porpoise (Phocoena phocoena), and a common dolphin (Delphinus delphis); (Ross et al., 1994) and from an aborted bottlenose dolphin (Tursiops truncatus) fetus (Ewalt et al., 1994). Subsequently antibodies to and isolates of this marine Brucella were detected in multiple marine mammal species (Foster et al., 1996; Nielson et al., 2001). Marine Brucella spp. have been classified as two species, Brucella ceti and Brucella pinnipedialis, for isolates from cetaceans and seals, respectively (Cloeckaert et al., 2001; Foster et al., 2007; Banai and Corbel, 2010) with subgroups identified within each (Maquart et al., 2009). Like terrestrial isolates, B. ceti and potentially B. pinnipedialis, are zoonotic (Cloeckaert et al., 2011). In 1999 a case of laboratory-acquired brucellosis of marine origin occurred (Brew et al., 1999). Subsequently, three cases of naturally acquired brucellosis of marine origin were reported from people having no known DOI: 10.7589/2012-05-137 Journal of Wildlife Diseases, 49(4), 2013, pp. 802–815 # Wildlife Disease Association 2013 802