Mareks disease (MD), caused by a highly contagious and oncogenic herpesvirus, causes immunosuppression and tumours in chickens. Although several reports on occurring lymphomas (MD-like conditions) in turkeys were published in the past less attention has been paid to the disease in this species. Recently, Mareks disease virus (MDV) has been demonstrated in lymphomatous tumours in commercial turkeys in several countries. The present review describes the past and recent history of MD in turkeys, clinical picture, and methods used for diagnosis. Additionally, three hypotheses might explain the emergence and re-emergence of MDV in turkeys including virus evolution and evolution of MDV variants, modern hybrid turkeys, and raising of turkeys close to chickens. Although the HVT vaccine didn`t protect turkeys against challenge with a virulent MDV strain, Rispens strain vaccine is effective against MDV in turkey. The pathogenesis of MDV infection in turkeys remains unclear and further investigations are necessary. Additionally, the effectiveness of MDV vaccines needs to be assessed in turkeys.
Key words: Mareks disease, Oncogenic virus, Tumours, HVT, Rispens, PCR
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