Marek's disease: A global challenge to poultry health and productivity

Marek's disease is a neuropathic and lymphoproliferative viral condition that primarily affects chickens and occasionally affects quail and turkeys. It is caused by the Marek's disease virus (MDV), a member of the family Herpesviridae, subfamily Alphaherpesvirinae, genus Mardivirus, which comprises three distinct species: MDV-1, MDV-2, and MDV-3 (herpesvirus of turkeys). Marek's disease remains a significant global challenge despite the availability of vaccines, with outbreaks still occurring in many poultry-producing regions due to the evolving virulence of the virus and incomplete protection. The current literature provides abundant information on the etiology, pathogenesis, and control of Marek's Disease; however, an up-to-date, comprehensive synthesis that integrates recent molecular insights, epidemiological patterns, and advanced control strategies is lacking. This review addresses this gap by systematically compiling and analyzing recent studies published in peer-reviewed journals, selected through database searches in PubMed, Scopus, and Web of Science using predefined inclusion and exclusion criteria. Key findings highlight the complexity of MDV pathogenesis, virus persistence in the poultry environment, and limitations of existing vaccines in achieving sterile immunity. The review also underscores the importance of combining vaccination with genetic selection and strict biosecurity to mitigate economic losses. Understanding these interconnected factors is crucial for guiding future research and improving disease management strategies in the poultry industry.