Abstract
An obtunded, uncoordinated female northern sea otter pup (Enhydra lutris kenyoni), was found alone in surf near Anchor Point, Alaska, and was admitted to the Alaska SeaLife Center Stranding Program. Hematology and serum chemistries were within normal ranges. She showed gradual improvement with supportive care and empirical anti-inflammatory and antibiotic treatment. Bouts of tremor, disorientation and intermittent grand mal seizures were partially controlled with anticonvulsant medications. Blood lead level was within normal limits. Serology was negative for Toxoplasma, Neospora, Sarcocystis neurona, canine and phocine morbillivirus, seal herpesvirus and Leptospira species. CT and MRI revealed a skull fracture with an area of cerebral porencephalopathy.
Seven weeks after admission, a raised pink lesion appeared on the otter's abdomen and was biopsied. Histologically, the tissue showed marked epidermal hyperplasia with balloon degeneration and necrosis. Intracytoplasmic eosinophilic inclusions typical of Bollinger bodies were detected in epithelium of the epidermis. Poxvirus particles were imaged by negative stain and transmission electron microscopy in scrapings from the epidermal surface and in intact epithelium of the epidermis, respectively. Testing with a variety of PCR primers designed to identify known parapox and orthopox viruses did not amplify any recognizable virus.
The otter was euthanized. Necropsy confirmed a healing skull fracture with an associated focal frontal lobe defect. A focus of resolving malacia and vacuolation was detected in the brain (presumed countercoup lesion). The abdominal pox lesion was nearly healed but there was diffuse pronounced hyperplastic, papillomatous gingivitis in the oropharynx with small eosinophilic intracytoplasmic inclusion bodies suggestive of poxvirus. Additional testing of necropsy tissue is ongoing.
To our knowledge, this is the first report of cutaneous poxvirus in any mustelid species. The source of this virus and its significance is undetermined. Genetic sequencing is in process in an attempt to further characterize this unique infection.