Coxiella burnetii in Northern Fur Seals and Steller Sea Lions of Alaska

Abstract

Coxiella burnetii, a zoonotic bacterium, has recently been identified in several marine mammal species on the Pacific Coast of North America, but little is known about the epidemiology, transmission, and pathogenesis in these species. We tested sera archived from northern fur seals (NFS, Callorhinus ursinus; n=236) and Steller sea lions (SSL, Eumetopias jubatus; n=72) sampled in Alaska for C. burnetii antibodies, and vaginal swabs from NFS (n=40) for C. burnetii by qPCR. The antibody prevalence in NFS samples from 2009 and 2011 (69%) was significantly higher than in 1994 (49%). The antibody prevalence of SSL samples from 2007 to 2011 was 59%. All NFS vaginal swabs were negative for C. burnetii, despite an 80% antibody prevalence in the matched sera. The significant increase in antibody prevalence in NFS from 1994 to 2011 suggests that the pathogen may be increasingly common or that there is marked temporal variation within the vulnerable NFS population. The high antibody prevalence in SSL suggests that this pathogen may also be significant in the endangered SSL population. These results confirm that C. burnetii is more prevalent within these populations than previously known. More research is needed to determine how this bacterium may affect individual, population, and reproductive health of marine mammals.

Pathological findings and survey for pathogens associated with reproductive failure in perinatal Steller sea lions Eumetopias jubatus

“…Molecular and serological studies show that SSLs in the western stock and northern fur seals Callorhinus ursinus in Alaska have been exposed to infection by C. burnetii (e.g. Minor et al 2013), but it is unclear whether this pathogen causes disease in northern fur seals.…”

Coxiella burnetii exposure in northern sea otters Enhydra lutris kenyoni

“…The apparent seroprevalence (20%) in otters is significantly lower than that reported in NFSs (69%) and SSLs (59%) from an overlapping geographic range (Minor et al 2013). Reasons for this discrepancy could be related to differing species susceptibilities, but is more likely due to differing exposure probabilities.…”

“…Placental disease (Kersh et al 2010) and high placental and seroprevalence have been reported in Pacific harbor seals Phoca vitulina, harbor porpoises Phocoena phocoena and Steller sea lions Eumetopias jubatus (SSL) of the Pacific Northwest (Kersh et al 2012). In Alaska, approximately 75% of northern fur seal Callorhinus ursinus (NFS) placentas tested positive for C. burnetii by real-time PCR (qPCR) (Duncan et al 2012(Duncan et al , 2013 and there is a high seroprevalence in both the NFS and the sympatric SSL populations (Minor et al 2013). Environmental contamination and the persistence of C. burnetii on pinniped rookeries has been proposed a potential source of bacteria for other species (Duncan et al 2013); however, the level of exposure and disease in other species throughout the region is largely unknown.…”

Prevalence of Coxiella burnetii and Brucella spp. in tissues from subsistence harvested northern fur seals (Callorhinus ursinus) of St. Paul Island, Alaska

“…That all samples were negative for C. burnetii was unexpected. The 2011 C. burnetii seroprevalence in subadult males was 73% [ 17 ] suggesting that exposure is high in the cohort of animals included in the present study. Failure to identify any tissues positive by PCR suggests that for exposed NFS the infection rate is low, infection is transient or the bacteria persists in tissues other than those tested in this study.…”