Marek's Disease is a viral infection that primarily affects chickens, caused by the Marek's disease virus (MDV), a type of herpesvirus. It leads to tumors in various organs and tissues, resulting in symptoms such as paralysis, weight loss, and changes in feathering. The disease can spread through direct contact or contaminated environments. Vaccination is a common preventive measure against Marek's Disease, and many poultry farms implement it to protect their flocks. The disease can significantly impact the poultry industry, leading to economic losses due to decreased productivity and increased mortality rates among affected birds.