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

Abstract

BackgroundThe 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.FindingsOf 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.ConclusionsFindings suggest that the risk of humans contracting brucellosis or Q fever from the consumption of harvested northern fur seals is low.

Brucella Antibodies in Alaskan True Seals and Eared Seals—Two Different Stories

“…Terrestrial brucellae of unknown origin have also been detected by PCR in blood and milk from two apparently clinically healthy wild California sea lions, and marine mammal brucellae were detected in blood and milk from one animal ( 19 ). B. pinnipedialis has also been detected by PCR in six Northern fur seal placentas, of which one had severe placentitis ( 18 ), and in one Northern fur seal spleen with no pathology associated ( 45 ). The low number of isolates and PCR-positive cases obtained from eared seals make drawing any conclusions regarding the presence or absence of pathology in these species difficult, however, it is worth noticing that the few cases reported have often been associated with pathology in the reproductive organs ( 16 – 18 ) and that transplacental transmission has been suggested ( 16 ).…”

A Review of Northern Fur Seal (Callorhinus ursinus) Literature to Direct Future Health Monitoring Initiatives

“…Infected placentas had decreased apoptosis of placental trophoblasts suggesting a functional change in the tissue, although no information on the associated NFS pup was available to support this claim [29]. PCR conducted on multiple tissue types from 50 subadult male NFSs harvested during subsistence hunting were tested for C. burnetii bacterial DNA by real-time PCR; there were no positive samples [30]. Similarly, archived vaginal swabs from adult female NFSs were all negative [31].…”

“…Another serosurvey of 107 archived samples collected in the same area, but tested by enzyme-linked immunoassay (ELISA), were all negative [33]. Fifty subsistence harvested subadult male NFSs were tested by PCR using eight tissue types, but only a single spleen sample was positive and no disease was reportedly observed [30].…”

Establishing a reference interval for acute phase proteins, cytokines, antioxidants and commonly measured biochemical and hematologic parameters in the northern fur seal (Callorhinus ursinus)

“…Northern fur seals are highly migratory and only come ashore during the summer to give birth and breed, making it difficult to definitively determine the cause of the observed decrease in numbers. Various contributory factors have been postulated to impact marine mammal populations such as infectious disease environmental pollutants and decreased availability of food from fishing and/or climate change (Beckmen et al, 2003;Chatterton et al, 2020;Dufresne et al, 2010;Duncan et al, 2014a;Foster et al, 2018). While it is likely that the NFS decline is related to a combination of factors, determining the elements involved are critical to understanding potential threats to population recovery.…”