Diagnostic investigation of Marek's disease in a turkey

Abstract

A six-month-old female turkey from a commercial growing unit was evaluated at postmortem examination for investigation of suspected viral lymphoproliferative disease. Clinically, the turkey was dull and subdued, and relatively unresponsive to external stimuli. The main gross postmortem findings were diffusely enlarged spleen, kidneys and liver, with multifocal cream foci. The lungs were atelectatic, and mild segmental mural thickening of the small intestines was observed. Impression smears taken during postmortem examination confirmed the presence of a population of neoplastic lymphocytes, which, on histological examination, infiltrated multiple organs. Using quantitative real-time PCR analysis, spleen and liver samples were positive for Marek's disease virus and negative for herpesvirus of turkeys. A splenic sample was negative for reticuloendotheliosis virus. This case report details gross, cytological and histological findings in a confirmed case of Marek's disease in a turkey where disease manifests as infiltration of numerous organs with pleomorphic neoplastic lymphocytes.

Pathological and Immunohistochemical Examinations on Co-Infection with Coligranulomatosis and Marek's Disease in a Turkey Flock

“…In experimental studies, the lesions seen in the nerves were either rarely encountered or not at all. However, it has been noted that lymphoproliferative lesions occurring in visceral organs in chickens are also seen in turkeys (Hughes et al, 2016;Nair et al, 2020). In the acute form, while pleomorphic lymphocyte deposits were observed in the visceral organs, it was reported that clinical findings were less pronounced, in this case, deaths could increase rapidly and reach 70% in large outbreaks (Nair et al, 2020).…”

“…Although histopathological changes in Marek's disease are well defined in chickens, limited findings have been reported in turkeys (Pennycott and Venugopal, 2002). It has been reported that the most characteristic histopathological finding is pleomorphic lymphocytes and mononuclear cells infiltration in multiple organs as in chicken (Hughes et al, 2016;Nair et al, 2020;Pattison et al, 2008). Nevertheless, it has been stated that macroscopic and microscopic findings observed in chickens are not frequently observed or not evident in turkeys (Blake-Dyke and Baigent S, 2013; Deuchande et al, 2012;Hughes et al, 2016;Pennycott and Venugopal, 2002;Voelckel et al, 1999).…”

“…While Marek's disease is common in chickens, it is much less common in turkeys (Hughes et al, 2016). Although histopathological changes in Marek's disease are well defined in chickens, limited findings have been reported in turkeys (Pennycott and Venugopal, 2002).…”

“…In turkeys, this type of tumoral lesions may be caused by Marek's disease virus, Avian leukosis virus, Reticuloendotheliosis virus, or Lymphoproliferative disease virus (Pennycott and Venugopal, 2002). The immunohistochemical method has been indicated to be able to provide very useful information in the differential diagnosis (Haridy et al, 2009;Hughes et al, 2016;Yavuz and Erer, 2017). For this purpose, in IHC staining using MDV specific antibodies, immunopositive reactions were observed in the cytoplasm and nuclei of lymphocytes and histiocytes in tumor foci in the selected liver and intestine tissues.…”

“…It has been reported that the most characteristic histopathological finding is pleomorphic lymphocytes and mononuclear cells infiltration in multiple organs as in chicken (Hughes et al, 2016;Nair et al, 2020;Pattison et al, 2008). Nevertheless, it has been stated that macroscopic and microscopic findings observed in chickens are not frequently observed or not evident in turkeys (Blake-Dyke and Baigent S, 2013; Deuchande et al, 2012;Hughes et al, 2016;Pennycott and Venugopal, 2002;Voelckel et al, 1999). In chickens, neural involvement is often observed, characterized by pleomorphic lymphocyte infiltrations, which may result in macroscopically thickening of the peripheral nerves (Pattison et al, 2008).…”