Marek's Disease in a Flock of Japanese Quails (Coturnix japonica) in Germany.

A case of increased mortality was investigated at a German farm housing Japanese quails () for egg production. Different age groups were kept in aviaries in one barn. The quail chicks had diarrhea and the adults were emaciated, some also with diarrhea and conjunctivitis. Postmortem examination showed gross tumorlike lesions in 7 of 15 adult quails examined, with ocular lesions in 2 of them. On histopathological examination, infiltrates of monomorphic round cells were found in liver, spleen, lung, and proventriculus. In the eyes of two quails, similar cells were infiltrating the choroid layer, limbus, and adjacent parts of the cornea. Malignant lymphoma was diagnosed. Immunohistochemical examination identified tumor cells as T cells, and -specific PCR was positive for five quails with gross lesions. Additionally, and were detected in the chicks and spp. and coccidia in the adults. Marek's EcoQ protein (Meq) gene from was sequenced and analyzed, confirming Marek's disease. The results of our examinations demonstrate that the ocular lesions were caused by Marek's disease and that the gene from was detected in the flock of quails. As a control strategy for Marek's disease in quails, an all-in/all-out system was introduced. Additional laying quails acquired from a breeder at 35 days of life were vaccinated at stabling with a combined turkey herpesvirus (HVT)-Rispens vaccine and 14 days later with a Rispens vaccine. Subsequently, the losses and laying rates returned to normal.