Eastern equine encephalitis in a captive harbor seal (Phoca vitulina).
A 31-yr-old male, captive harbor seal (Phoca vitulina) was evaluated for a 48-hr period of anorexia followed by the onset of seizures. A prolonged seizure failed to respond to anticonvulsant therapy and the animal was euthanized. At necropsy, no significant gross lesions were identified. Reverse transcriptase-polymerase chain reaction testing of brain samples was positive for eastern equine encephalitis virus (EEEV) RNA, and serum was positive for anti-EEEV antibodies by plaque reduction neutralization. Histopathologic evaluation revealed severe and multifocal encephalitis with leptomeningitis, characterized by neutrophilic infiltrates in neuropil, neuronal necrosis, satellitosis, neuronophagia, and perivascular cuffs of lymphocytes, macrophages, and neutrophils. Additionally there was moderate, multifocal, adrenal cortical necrosis. Immunohistochemical staining for EEEV demonstrated viral antigen within necrotic neurons and glial cells. Virus was isolated from frozen brain tissue, sequenced for comparison to other strains, and determined to be a typical North American strain. EEEV should be included as a possible cause of neurologic disease in harbor seals with compatible signs located in geographic regions where vector transmission of EEEV is encountered.
McBride
Michael P
MP
Buttonwood Park Zoo, 425 Hawthorn Street, New Bedford, Massachusetts 02740, USA. mmcbride@rwpzoo.org
Sims
Michele A
MA
Cooper
Robert W
RW
Nyaoke
Akinyi C
AC
Cullion
Cheryl
C
Kiupel
Matti
M
Frasca
Salvatore
S
Forrester
Naomi
N
Weaver
Scott C
SC
Weber
E Scott
ES
D000818:Animals; D000836:Animals, Zoo; D000914:Antibodies, Viral / Q000097:blood; D001921:Brain / Q000473:pathology / Q000821:virology; D003937:Diagnosis, Differential; D004663:Encephalitis Virus, Eastern Equine / Q000302:isolation & purification*; D020242:Encephalomyelitis, Eastern Equine / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*; D017809:Fatal Outcome; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D046049:Phoca / Q000821:virology*; D012367:RNA, Viral / Q000032:analysis; D012640:Seizures / Q000209:etiology / Q000662:veterinary
D000914:Antibodies, Viral; D012367:RNA, Viral