Eastern equine encephalitis in 9 South American camelids.
BACKGROUND
Eastern equine encephalitis (EEE) virus is a mosquito-borne togavirus (alphavirus) that causes severe (often fatal) encephalitis in many mammalian species, but it has not been reported previously in South American camelids.


OBJECTIVE
South American camelids can become naturally infected with EEE virus and show encephalitic signs similar to those observed in other affected species.


METHODS
Nine cases (8 alpacas and 1 llama, aged 3.5 weeks to 12 years) were identified; 4 of 9 were 510 weeks old. All cases were from the East Coast of the United States and presented in late summer and fall.


METHODS
A retrospective study was performed to include confirmed cases of EEE in camelids in North America before 2006.


RESULTS
Eight of nine (89%) camelids died or were euthanized in extremis, with the mean time to death of 2 days. Clinical signs were consistent with encephalitis and included fever, lethargy, ataxia, seizures, recumbency, torticollis, opisthotonus, and vestibular signs. No consistent hematologic abnormalities were identified, and cerebrospinal fluid contained an increased protein concentration in the single camelid analyzed. No successful therapy was identified. EEE was confirmed by alphavirus detection by using immunohistochemistry (IHC) and polymerase chain reaction (PCR) in the central nervous system (CNS) and by serology. Findings included polioencephalitis with lymphocytic perivascular cuffing; neutrophil infiltration; gliosis; neuron satellitosis; necrosis; and edema, with intracytoplasmic alphavirus within neurons and glial cells. No virus was detected in extraneural tissues.


CONCLUSIONS
In endemic areas, EEE should be considered a differential diagnosis for young and adult camelids with CNS disease. Brain histopathology with indirect IHC or PCR is diagnostic.
Nolen-Walston
Rose
R
Tufts Cummings School of Veterinary Medicine, N. Grafton, MA, USA. rnolenw@vet.upenn.edu
Bedenice
Daniela
D
Rodriguez
Carlos
C
Rushton
Steven
S
Bright
Amy
A
Fecteau
Marie-Eve
ME
Short
Diana
D
Majdalany
Ron
R
Tewari
Deepanker
D
Pedersen
Douglas
D
Kiupel
Matti
M
Maes
Roger
R
Del Piero
Fabio
F
D000820:Animal Diseases / Q000175:diagnosis* / Q000473:pathology / Q000821:virology; D000818:Animals; D001921:Brain / Q000473:pathology; D002161:Camelids, New World / Q000821:virology*; D020242:Encephalomyelitis, Eastern Equine / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D005260:Female; D008297:Male; D012189:Retrospective Studies