*Virus isolation is the most definitive diagnostic method for EEE or WEE. Brain is preferred, but virus has also been isolated from the liver and spleen. Samples of these tissues should be taken in duplicate, one set for virus isolation and the other placed in formalin for histopathology. Viral isolation specimens should be sent frozen unless they can be received refrigerated within 48 hours of sampling. Unless clinical signs persist for more than 5days prior to death, EEE virus is frequently isolated from equine brain tissue. WEE virus, however, is rarely isolated from tissues of infected horses. Newborn mice, chicken embryos and a number of cell culture systems can be used for virus isolation. Virus may also be isolated from cerebrospinal fluid (CSF) of acutely infected horses. | *Virus isolation is the most definitive diagnostic method for EEE or WEE. Brain is preferred, but virus has also been isolated from the liver and spleen. Samples of these tissues should be taken in duplicate, one set for virus isolation and the other placed in formalin for histopathology. Viral isolation specimens should be sent frozen unless they can be received refrigerated within 48 hours of sampling. Unless clinical signs persist for more than 5days prior to death, EEE virus is frequently isolated from equine brain tissue. WEE virus, however, is rarely isolated from tissues of infected horses. Newborn mice, chicken embryos and a number of cell culture systems can be used for virus isolation. Virus may also be isolated from cerebrospinal fluid (CSF) of acutely infected horses. |