Marek Disease

Marek disease is a highly contagious viral disease of poultry caused by a herpes virus and characterized by T-cell lymphomas and peripheral nerve enlargement. Young birds are susceptible to infection and most deaths from Marek's disease occur between 8 and 20 weeks of age. The virus can survive in the environment for as long as several months at room temperature and is transmitted by a chicken breathing in infected dust and dander particles that are shed from the feather follicles of infected birds. Diagnosis is by ELISA antigen-antibody detection to MDV in non-vaccinated chickens from about 4 weeks of age or PCR analysis. It is also critical to diagnose the tumors and not just the infection because Marek disease is considered ubiquitous within commercial poultry flocks.