Abstract
The Apicomplexan protozoan parasite Neospora caninum has long been recognized as a significant cause of abortion and perinatal loss in cattle as well as neurologic and musculoskeletal disease in dogs.1 Antibodies to N. caninum have recently been detected in a variety of terrestrial wildlife, avian and marine mammal species, suggesting this parasite may possess a broader host range than previously envisaged.2,3 In this study, tissue samples collected from 168 stranded dead marine mammals along the North Eastern Pacific Ocean, including Oregon, Washington, British Columbia and Alaska coasts between 2004 and 2013 were suspected to be infected with a protozoal agent. These tissues were examined for infection with N. caninum using histology, immunohistochemistry and multi-locus polymerase chain reaction PCR-DNA sequencing at 18S and ITS1 loci. Of the 168 individuals examined, three Pacific harbor seals (Phoca vitulina richardsi), two northern sea otters (Enhydris lutris) one Steller sea lion (Eumetopias jubatus), and one Guadalupe fur seal (Arctocephalus townsendi) were PCR-DNA sequence positive for N. caninum. Another 19 individuals were PCR positive for orthologous coccidian parasites whose DNA sequence most closely resembled, but was distinct from, Neospora caninum. Furthermore, the detection of N. caninum parasite cysts by immunohistochemistry in the neuropil of a preweaned harbor seal pup may suggest that transplacental infection is another important route for parasite exposure. Canids are the only known definitive host to excrete Neospora caninum oocysts, whether Neospora caninum infection in such a broad range of marine mammal species is influenced by canid fecal contamination in terrestrial runoff, is unknown. Studies are underway to determine if marine mammals transiting or residing in areas of fresh water discharge and estuaries downstream from intensively farmed dairy cattle with a hyperendemic focus of N. caninum infection possess a greater at-risk exposure to infection, impaired reproductive performance, or neonatal loss at the population level.
* Presenting author
Literature Cited
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