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

Abstract

Steller sea lions (SSLs) Eumetopias jubatus experienced a population decline in the 1960s, leading to the listing of the western stock as endangered and the eastern stock as threatened under the US Endangered Species Act. A decrease of births in the western stock beginning in the late 1960s indicates that reproductive failure may have contributed to the decline. We evaluated the role pathogens play in spontaneous abortions, premature births and neonatal deaths in SSLs. Archived tissues from carcasses (n = 19) collected in Alaska from 2002 to 2015 were tested by PCR for Coxiella burnetii, Brucella spp., Chlamydia and morbilliviruses. Animals examined included 47% premature pups, 32% aborted fetuses, 11% neonates and 11% intrauterine fetuses. Gross necropsy and histology findings were summarized in the context of the PCR findings. Tissues were negative for Chlamydia and C. burnetii. Brucella spp. were detected in the lung tissues of 3 animals, including 1 positive for the ST27 strain, the first detection of Brucella spp. DNA in SSLs. Phocine distemper virus was detected in 3 animals in 2 skin lesions and 1 placenta by heminested diagnostic qRT-PCR. Both skin and the placental lesions had vesiculoulcerative changes, and 1 skin lesion contained inclusion bodies in syncytia and upon histologic examination, suggesting that the lesions may be associated with an infection reminiscent of phocine distemper virus, the first in SSLs. We highlight the continuing need for disease surveillance programs to improve our understanding of the prevalence and potential population impacts of these infectious disease agents for pinnipeds in Alaskan waters.

Serologic studies of bacterial zoonoses in free-living sea lion pups Zalophus californianus, in the Gulf of California, Mexico

“…A previous study on Steller sea lions in Alaska found Chlamydia spp. (Esquible et al 2019). Further evidence that justified the present research is the findings of Chlamydia psittaci in water birds from New Zealand and water birds kept in a wildlife rescue center from the west of France, in the North Atlantic (Aaziz et al 2015, Soon et al 2021.…”

“…In Alaska, Brucella spp. was detected in Steller sea lions (Eumetopias jubatus) (Esquible et al 2019). However, other countries, such as New Zealand, have failed to identify whether brucellosis affects sea lions (Roe et al 2010).…”

Serological Detection of Marine Origin Brucella Exposure in Two Alaska Beluga Stocks

“…However, B. pinnipedialis infection in cetaceans has rarely been associated with pathology [ 22 , 23 ]. Furthermore, Brucella ST 27 has been identified in a single Steller sea lion ( Eumetopias jubatus ) in Alaska’s waters [ 24 ], highlighting the need for continued monitoring.…”

Novel and classical morbilliviruses: Current knowledge of three divergent morbillivirus groups

“…PDV is closely related to CDV, and primarily infects animals in the family Phocidae. PDV infection has also been reported in other pinnipeds, such as the walrus ( Odobenus rosmarus ), sea lion ( Eumetopias jubatus ), and New Zealand fur seal ( Arctocephalus forsteri ) 62–64 . It has also been reported that PDV infects animals in the family mustelidae (sea otters and minks) 65,66 .…”

“…PDV infection has also been reported in other pinnipeds, such as the walrus (Odobenus rosmarus), sea lion (Eumetopias jubatus), and New Zealand fur seal (Arctocephalus forsteri). [62][63][64] It has also been reported that PDV infects animals in the family mustelidae (sea otters and minks). 65,66 In the North Atlantic to Arctic region, there have been large PDV outbreaks in the past, and it is speculated that the virus circulates in the region.…”