Marek's Disease
Etiology
Marek's disease (MD) is a transmissible neoplastic disease, primarily affecting chickens. The disease is caused by a cell-associated herpesvirus, containing double-stranded DNA. There are three serotypes of MDV but oncogenicity is only associated with serotype 1 MDVs. Within this serotype however, there are many strains of MDV, whose pathogenicity varies widely. Subsequently, clinical signs in infected chickens vary from asymptomatic infection to neurologic disease, skin disease, and ocular lesions.
Host Range
Marek's disease is primarily a disease of commercial chickens, but it can also affect turkeys. MD often occurs in 2-5 month-old (sexually immature) chickens but can also occur after the onset of egg production. This form of the disease is referred to as
