Surveillance for zoonotic and selected pathogens in harbor seals phoca vitulina from central California

Denise J. Greig, Frances M D Gulland, Woutrina A Smith, Patricia A Conrad, Cara L. Field, Michelle Fleetwood, James T. Harvey, Hon S. Ip, Spencer Jang, Andrea Packham, Elizabeth Wheeler, Ailsa J. Hall

Research output: Chapter in Book/Report/Conference proceedingChapter

22 Scopus citations


The infection status of harbor seals Phoca vitulina in central California, USA, was evaluated through broad surveillance for pathogens in stranded and wild-caught animals from 2001 to 2008, with most samples collected in 2007 and 2008. Stranded animals from Mendocino County to San Luis Obispo County were sampled at a rehabilitation facility: The Marine Mammal Center (TMMC, n = 175); wild-caught animals were sampled at 2 locations: San Francisco Bay (SF, n = 78) and Tomales Bay (TB, n = 97), that differed in degree of urbanization. Low prevalences of Salmonella, Campylobacter, Giardia, and Cryptosporidium were detected, in the feces of stranded and wild-caught seals. Clostridium perfringens and Escherichia coli were more prevalent in the feces of stranded (58% [78 out of 135] and 76% [102 out of 135]) than wild-caught (42% [45 out of 106] and 66% [68 out of 106]) seals, whereas Vibrio spp. were 16 times more likely to be cultured from the feces of seals from SF than TB or TMMC (p < 0.005). Brucella DNA was detected in 3.4% of dead stranded harbor seeds (2 out of 58). Type A influenza was isolated from feces of 1 out of 96 wild-caught seals. Exposure to Toxoplasma gondii, Sarcocystis neurona, and type A influenza was only detected in the wild-caught harbor seals (post-weaning age classes), whereas antibody titers to Leptospira spp. were detected in stranded and wild-caught seals. No stranded (n = 109) or wild-caught (n = 217) harbor seals had antibodies to phocine distemper virus, although a single low titer to canine distemper virus was detected. These results highlight the role of harbor seals as sentinel species for zoonotic and terrestrial pathogens in the marine environment.

Original languageEnglish (US)
Title of host publicationDiseases of Aquatic Organisms
Number of pages14
StatePublished - Sep 30 2014


  • Campylobacter
  • Influenza
  • Leptospira
  • Morbillivirus
  • Neospora
  • Sarcocystis
  • Toxoplasma
  • Vibrio

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics
  • Medicine(all)


Dive into the research topics of 'Surveillance for zoonotic and selected pathogens in harbor seals phoca vitulina from central California'. Together they form a unique fingerprint.

Cite this