A viral metagenomic study was performed to investigate potential viral pathogens associated with a mortality event of three captive California sea lions (Zalophus californianus). This study identified a novel California sea lion anellovirus (ZcAV), with 35 % amino acid identity in the ORF1 region to feline anelloviruses. The double-stranded replicative form of ZcAV was detected in lung tissue, suggesting that ZcAV replicates in sea lion lungs. Specific PCR revealed the presence of ZcAV in the lung tissue of all three sea lions involved in the mortality event, but not in three other sea lions from the same zoo. In addition, ZcAV was detected at low frequency (11 %) in the lungs of wild sea lions. The higher prevalence of ZcAV and presence of the double-stranded replicative form in the lungs of sea lions from the mortality event suggest that ZcAV was associated with the death of these animals.New diseases in marine animals are emerging at an increasing rate and the causative agents of the diseases are mostly unknown (Harvell et al., 1999;Van Bressem et al., 1999). As animals are considered to be the source of .70 % of emerging human infections (Cleaveland et al., 2001), surveillance of pathogens in animals, especially in non-human vertebrates, is important for protecting the health of both humans and wild animal populations (Kruse et al., 2004;Kuiken, 2005).Investigating new viral infections has been difficult due to limitations of current detection methods (reviewed by Delwart, 2007). For example, degenerate PCR and panviral microarrays can detect viruses with close sequence similarity to known viruses, but are limited for discovering novel viruses that share limited similarity with previously sequenced virus genomes. Recent studies have demonstrated the effectiveness of virus-particle purification and shotgun sequencing (viral metagenomics) for describing novel viruses, including those that are unrelated to previously described virus families (Delwart, 2007;Edwards & Rohwer, 2005). The techniques of viral metagenomics were first applied to characterize virus communities present in the environment (Breitbart et al., 2002) One potential application of viral metagenomics is for examination of viral pathogens involved in unusual mortality events of animals. In 2005 and 2006, three California sea lions at the Kansas City Zoo, MO, USA, died in a mortality event of unknown aetiology. Necropsy and histopathology revealed granulomatous, non-suppurative mediastinitis and pleuritis in two of the sea lions, whilst the third sea lion was found to have an accumulation of lymphocytes and macrophages in the upper respiratory submucosa (W. K. Suedmeyer, unpublished results). Chemical toxicity assays using gas chromatography and mass spectroscopy did not detect pesticides, organic toxic compounds or abnormal mineral levels in pool water or gastric contents. All sea lions were negative for pathogenic bacteria, fungi and mycoplasma in culture-based assays and histopathology. The sea lions also tested negative for West Nile virus, ...

ABSTRACT:Domoic acid is a glutaminergic neurotoxin produced by marine algae such as Pseudonitzschia australis. California sea lions (Zalophus californianus) ingest the toxin when foraging on planktivorous fish. Adult females comprise 60% of stranded animals admitted for rehabilitation due to acute domoic acid toxicosis and commonly suffer from reproductive failure, including abortions and premature live births. Domoic acid has been shown to cross the placenta exposing the fetus to the toxin. To determine whether domoic acid was playing a role in reproductive failure in sea lion rookeries, 67 aborted and live-born premature pups were sampled on San Miguel Island in 2005 and 2006 to investigate the causes for reproductive failure. Analyses included domoic acid, contaminant and infectious disease testing, and histologic examination. Pseudo-nitzschia spp. were present both in the environment and in sea lion feces, and domoic acid was detected in the sea lion feces and in 17% of pup samples tested. Histopathologic findings included systemic and localized inflammation and bacterial infections of amniotic origin, placental abruption, and brain edema. The primary lesion in five animals with measurable domoic acid concentrations was brain edema, a common finding and, in some cases, the only lesion observed in aborted premature pups born to domoic acid-intoxicated females in rehabilitation. Blubber organochlorine concentrations were lower than those measured previously in premature sea lion pups collected in the 1970s. While the etiology of abortion and premature parturition was varied in this study, these results suggest that domoic acid contributes to reproductive failure on California sea lion rookeries.

To investigate viral pathogens potentially involved in a mortality event of 21 Pacific harbor seals (Phoca vitulina richardsii) in California in 2000, viral metagenomics was performed directly on lung samples from five individuals. Metagenomics revealed a novel seal anellovirus (SealAV), which clusters phylogenetically with anelloviruses from California sea lions and domestic cats. Using specific PCR, SealAV was identified in lung tissue from two of five animals involved in the 2000 mortality event, as well as one of 20 harbor seal samples examined post-mortem in 2008. The identification of SealAV in multiple years demonstrates that this virus is persistent in the harbor seal population. SealAV is the second anellovirus reported in the lungs of pinnipeds, suggesting that anellovirus infections may be common amongst marine mammals and that more research is needed to understand the roles of these viruses in marine mammal health and disease.

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...

The results suggested that viral presence in ocular tissues was common, not significantly associated with ocular disease and thus should not preclude release of an otherwise healthy animal. We could not confirm a correlation of virus presence with lesion due to the high percentage of virus-positive, clinically normal animals. This implied that seals and sea lions can have ocular tissues infected with several viruses without having readily evident associated lesions. This difficulty in correlating viral presence, particularly herpesviruses, with ocular lesions was also a common finding in studies with terrestrial species and highlighted the difficulty of confirming a virus as a primary pathogen in ocular lesions.