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A retrospective study was conducted to categorize and describe the causes of mortality in harbor seals (Phoca vitulina) along the British Columbia coast that presented to the Vancouver Aquarium Marine Mammal Rescue Centre (MMR) for rehabilitation from 2012 to 2020. Medical records for 1,279 predominantly perinatal live-stranded harbor seals recovered in this region were reviewed. Approximately 20.0% (256 individuals; 137 males, 118 females, 1 unknown) of these animals died while at MMR. Infectious disease was the most common cause of death, accounting for 60.5% of mortality across all age classes. This was followed by nonanthropogenic trauma (7.1%), metabolic illness (5.4%), nutritional deficiency (5.0%), parasitic illness (5.0%), congenital disorders (2.5%), and human-associated trauma (0.4%). Pups were the most common age class (87.4%) amongst mortalities and predominantly died of an infectious process (62.5%). Phocid herpesvirus-1 infection was identified in 18.9% of the mortalities, with the highest prevalence occurring in 2019 (30.8%). Fungal disease was detected in six seals: three cases of pulmonary mycosis due to Cryptococcus gattii and three cases consistent with mucormycosis. In six cases, mortality was attributed to congenital disorders. Two of these cases involved axial skeletal malformities that are not currently described in the literature. This is the first study to describe the causes of mortality in harbor seals undergoing rehabilitation in British Columbia., (© Wildlife Disease Association 2023.)

Cryptococcosis has been reported in marine mammals in the northeastern Pacific with increasing frequency in the last 15 yr. Although a variety of cetaceans have been diagnosed with cryptococcosis, Cryptococcus gattii has not been reported in pinnipeds. We document C. gattii VGIIa in a harbor seal ( Phoca vitulina ) pup and in an unrelated adult. Both animals were presented to Vancouver Aquarium's Marine Mammal Rescue Centre (VAMMRC) with generalized weakness, dehydration, respiratory compromise, minimally responsive mentation, and suboptimal body condition. Necropsy and histopathology findings were consistent in both animals and featured generalized lymphadenopathy, bronchopneumonia, and meningoencephalitis with intralesional yeast and fungemia. Cryptococcal serum antigen titers were ≥1,024 in both animals. Fungal culture of lung and lymph nodes confirmed C. gattii . Exposure was likely via inhalation prior to presentation to VAMMRC, and C. gattii infection was the proximate cause of death. This report expands the range of susceptible host species as C. gattii continues to emerge as a pathogen of concern in marine mammals in the northeastern Pacific.

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Humans are commonly exposed via inhalation of aerosolized bacteria derived from the waste products of domesticated sheep and goats, and particularly from products generated during parturition. However, many other species can be infected with C. burnetii, and the host range and full zoonotic potential of C. burnetii is unknown. Two cases of C. burnetii infection in marine mammal placenta have been reported, but it is not known if this infection is common in marine mammals. To address this issue, placenta samples were collected from Pacific harbor seals (Phoca vitulina richardsi), harbor porpoises (Phocoena phocoena), and Steller sea lions (Eumetopias jubatus). Coxiella burnetii was detected by polymerase chain reaction (PCR) in the placentas of Pacific harbor seals (17/27), harbor porpoises (2/6), and Steller sea lions (1/2) collected in the Pacific Northwest. A serosurvey of 215 Pacific harbor seals sampled in inland and outer coastal areas of the Pacific Northwest showed that 34.0% (73/215) had antibodies against either Phase 1 or Phase 2 C. burnetii. These results suggest that C. burnetii infection is common among marine mammals in this region.

Previously, we reported the isolation of Bartonella henselae from the blood of harbor porpoises (Phocoena phocoena) and loggerhead sea turtles (Caretta caretta) from the North Carolina coast. Hematologic, pathologic, and microbiologic findings surrounding the death of a juvenile captive beluga in Vancouver initiated an outbreak investigation designed to define the molecular prevalence of Bartonella infection in belugas. Using polymerase chain reaction analyses targeting the intergenic spacer region (ITS), two B. henselae ITS strains were identified in 78% of captive and free-ranging hunter-harvested belugas. These findings may have public health implications and may influence aquarium management procedures for captive marine mammals.