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 seals (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 wildcaught (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.KEY WORDS: Campylobacter · Leptospira · Influenza · Morbillivirus · Neospora · Sarcocystis · Toxoplasma · Vibrio
Resale or republication not permitted without written consent of the publisherDis Aquat Org 111: [93][94][95][96][97][98][99][100][101][102][103][104][105][106] 2014 affect marine mammals are zoonoses, raising concerns that marine mammal excretions may pose a risk to human health (Knap et al. 2002). Human exposure by fecal, oral, or respiratory routes could occur in the water, on docks, boats, or beaches, or through occupational health exposure.Zoonotic pathogens known to cause disease in harbor seals include influenza A (Geraci et al. 1982, Anthony et al. 2012, Brucella (Garner et al. 1997), Toxoplasma gondii (Lapointe et al. 1998, Miller et al. 2001, and Leptospira interrogans (Stamper et al. 1998, Stevens et al. 1999. Surveys of apparently healthy seals in remote areas considered to be relatively pristine have demonstrated exposure to zoonotic bacteria such as Brucella spp., and protozoa such as Giardia, T. gondii, and Sarcocystis neurona (Olson et al. 1997, Dubey et al. 2003, Zarnke et al. 2006, Jensen et al. 2010, highlighting the role that marine mammals may play both as sentinels of pathogen pollution in the marine environment and as potential reservoirs for pathogens that could affect humans (Ross 2000). There...