Valvular endocarditis has been well described in northern sea otters Enhydra lutris kenyoni of Alaska and in many cases no cause has been identified. It is also one of the most common conditions observed in people with chronic Coxiella burnetii infection. Given the high levels of C. burnetii exposure in marine mammals distributed throughout the same geographic range as the northern sea otter, and the presence of valvular lesions seen in otters, the objective of this study was to determine the level of C. burnetii exposure in otters and investigate any association between exposure, infection and valvular disease in this species. Archived serum from 75 live captured, apparently healthy otters (25 from each of 3 stocks) and 30 dead otters were tested for C. burnetii antibodies by indirect florescent antibody assay (IFA). Archived bone marrow and heart valves were tested for C. burnetii DNA by real-time PCR (qPCR). Overall, the seroprevalence in live otters was 17%, with significantly more exposed animals in the south central (40%) stock relative to the southwest (8%) and southeast (4%). The seroprevalence of animals sampled post mortem was 27%, although none of the bone marrow or heart valve samples were positive by qPCR. Results of this study failed to demonstrate a significant association between C. burnetii infection and valvular endocarditis in sea otters; however, the differing seroprevalence suggests that exposure opportunities vary geographically.
The decline in the number of northern fur seal (NFS; Callorhinus ursinus) pups on St. Paul Island, Alaska, has led to multidisciplinary research, including investigation into issues of reproductive health and success. Given the recent identification of Coxiella burnetii in the placenta of two other marine mammal species, NFS placentas were collected from Reef rookery on St. Paul Island, Alaska, during the 2010 pupping season, examined histologically, and tested for C. burnetii using polymerase chain reaction (PCR). Of 146 placentas examined, gram-negative intratrophoblastic bacteria that were positive for C. burnetii on immunohistochemistry were observed in 5 (3%) placentas. Placental infection was usually devoid of associated inflammation or significant ancillary pathology. One hundred nine (75%) of the placentas were positive for C. burnetii on PCR. C. burnetii is globally distributed and persists for long periods in the environment, providing ample opportunity for exposure of many species. The significance of this finding for the declining fur seal population, potential human exposure and infection, and impact on other sympatric marine mammal or terrestrial species is unclear; further investigation into the epidemiology of Coxiella in the marine ecosystem is warranted.
It has been over a decade since Cryptococcus gattii was first recognized as the causative organism of an outbreak of cryptococcosis on Vancouver Island, British Columbia. A number of novel observations have been associated with the study of this emergent pathogen. A novel genotype of C. gattii, VGIIa was described as the major genotype associated with clinical disease. Minor genotypes, VGIIb and VGI, are also responsible for disease in British Columbians, in both human and animal populations. The clinical major genotype VGIIa and minor genotype VGIIb are identical to C. gattii isolated from the environment of Vancouver Island. There is more heterogeneity in VGI, and a clear association with the environment is not apparent. Between 1999 and 2010, there have been 281 cases of C. gattii cryptococcosis. Risk factors for infection are reported to be age greater than 50 years, history of smoking, corticosteroid use, HIV infection, and history of cancer or chronic lung disease. The major C. gattii genotype VGIIa is as virulent in mice as the model Cryptococcus, H99 C. neoformans, although the outbreak strain produces a less protective inflammatory response in C57BL/6 mice. The minor genotype VGIIb is significantly less virulent in mouse models. Cryptococcus gattii is found associated with native trees and soil on Vancouver Island. Transiently positive isolations have been made from air and water. An ecological niche for this organism is associated within a limited biogeoclimatic zone characterized by daily average winter temperatures above freezing.
Recent decline of sea ice habitat has coincided with increased use of land by polar bears (Ursus maritimus) from the southern Beaufort Sea (SB), which may alter the risks of exposure to pathogens and contaminants. We assayed blood samples from SB polar bears to assess prior exposure to the pathogens Brucella spp., Toxoplasma gondii, Coxiella burnetii, Francisella tularensis, and Neospora caninum, estimate concentrations of persistent organic pollutants (POPs), and evaluate risk factors associated with exposure to pathogens and POPs. We found that seroprevalence of Brucella spp. and T. gondii antibodies likely increased through time, and provide the first evidence of exposure of polar bears to C. burnetii, N. caninum, and F. tularensis. Additionally, the odds of exposure to T. gondii were greater for bears that used land than for bears that remained on the sea ice during summer and fall, while mean concentrations of the POP chlordane (SCHL) were lower for land-based bears. Changes in polar bear behavior brought about by climate-induced modifications to the Arctic marine ecosystem may increase exposure risk to certain pathogens and alter contaminant exposure pathways.
Cites: Environ Toxicol Chem. 2017 May;36(5):1181-119228054401
In July 2014, our investigative team traveled to St. Paul Island, Alaska to measure concentrations of radiocesium in wild-caught food products, primarily northern fur seal (Callorhinus ursinus). The 2011 Fukushima Daiichi Nuclear Power Plant accident released radiocesium into the atmosphere and into the western Pacific Ocean; other investigators have detected Fukushima-derived radionuclides in a variety of marine products harvested off the western coast of North America. We tested two subsistence-consumed food products from St. Paul Island, Alaska for Fukushima-derived radionuclides: 54 northern fur seal, and nine putchki (wild celery, Angelica lucida) plants. Individual northern fur seal samples were below minimum detectable activity concentrations of (137)Cs and (134)Cs, but when composited, northern fur seal tissues tested positive for trace quantities of both isotopes. Radiocesium was detected at an activity concentration of 37.2 mBq (134)Cs kg(-1) f.w. (95% CI: 35.9-38.5) and 141.2 mBq (137)Cs kg(-1) f.w. (95% CI: 135.5-146.8). The measured isotopic ratio, decay-corrected to the date of harvest, was 0.26 (95% CI: 0.25-0.28). The Fukushima nuclear accident released (134)Cs and (137)Cs in roughly equal quantities, but by the date of harvest in July 2014, this ratio was 0.2774, indicating that this population of seals has been exposed to small quantities of Fukushima-derived radiocesium. Activity concentrations of both (134)Cs and (137)Cs in putchki were below detection limits, even for composited samples. Northern fur seal is known to migrate between coastal Alaska and Japan and the trace (134)Cs in northern fur seal tissue suggests that the population under study had been minimally exposed Fukushima-derived radionuclides. Despite this inference, the radionuclide quantities detected are small and no impact is expected as a result of the measured radiation exposure, either in northern fur seal or human populations consuming this species.
The northern fur seal (Callorhinus ursinus) is an important cultural and nutritional resource for the Aleut community on St. Paul Island Alaska. In recent years, an increasing number of zoonotic pathogens have been identified in the population, but the public health significance of these findings is unknown. To determine the prevalence of Coxiella burnetii and Brucella spp. in northern fur seal tissues, eight tissue types from 50 subsistence-harvested fur seals were tested for bacterial DNA by real-time polymerase chain reaction.
Of the 400 samples tested, only a single splenic sample was positive for Brucella spp. and the cycle threshold (ct) value was extremely high suggesting a low concentration of DNA within the tissue. C. burnetii DNA was not detected.
Findings suggest that the risk of humans contracting brucellosis or Q fever from the consumption of harvested northern fur seals is low.