Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: June 5, 2014
Publication Date: June 5, 2014
Citation: Fadly, A.M. 2014. Tumorous diseases of turkeys - an update. In: Proceedings of the 10th "Hafez" International Symposium on Turkey Diseases, June 5-7, 2014, Berlin Germany. Technical Abstract: This update is primarily focused on addressing various aspects of virus-induced tumorous diseases of turkeys including review of current methods for diagnosis and control of these diseases of turkeys. Virus-induced tumorous diseases of turkeys are caused primarily by retroviruses, namely reticuloendotheliosis (RE) virus (REV) and lymphoproliferative disease (LPD) virus (LPDV). Although Marek’s disease (MD), a herpesvirus-induced T-cell lymphoma of chickens, has been diagnosed in commercial turkey flocks in several countries, the conditions that lead to, and the economic significance of such MD outbreaks are poorly understood. REV infection in turkeys is primarily expressed as chronic lymphomas (reticular cell tumor or T-cell lymphoma). Crespo et al., 2002 reported T-cell lymphomas associated with an outbreak of REV infection in turkey breeders and growers. The economic losses from such REV infection in affected turkey flocks were significant because of tumor mortality and loss of production. To date, no vaccines are available for control of REV infection, and no method has been routinely used by industry to control REV infection in either commercial turkey or chicken flocks. Partial or complete REV genome insertion in large DNA avian viruses such as MD and fowlpox viruses have been well documented, suggesting a role of such insertion in the epidemiology and transmission of REV infection in both chickens and turkeys. LPDV infection and tumors in commercial turkeys were first reported in the United Kingdom by Biggs et al. in 1974. However, the incidence of LPDV infection in turkeys has always been sporadic and the disease has not been reported in commercial turkeys during at least the last two decades. Most recently, however, Allison et al., 2014 described the widespread distribution, genetic diversity, pathogenesis and evolution of LPDV in the United States. In this recent report, LPDV infection and tumors were reported for the first time in wild turkeys in several regions in the United States. To date, the possibility of transmission of LPDV infection from wild turkeys to commercial turkey flocks in the United States has not been determined and needs to be evaluated.