How did vaccination reduce losses from Marek’s disease in chickens?

In the context of poultry farming, vaccination has been the primary method for controlling Marek’s disease, a highly contagious and often fatal malignancy caused by a herpesvirus that affects the nerves and visceral organs of chickens.12

Following the identification of the virus in 1967, the development of a vaccine provided a breakthrough in animal health management. This intervention significantly reduced losses in the poultry industry by achieving the following results in vaccinated flocks:12

• Disease Frequency: The incidence of Marek’s disease was reduced by 90 percent.2
• Meat Quality: Meat condemnations—the rejection of poultry carcasses due to disease—decreased by 90 percent.2
• Productivity: Egg production increased by 4 percent.2

This achievement is notable as the first successful use of an antiviral vaccine to prevent a naturally occurring malignancy. By mitigating the economic impact of a disease that previously cost the U.S. poultry industry more than $200,000,000 annually, vaccination remains a cornerstone of animal health and efficient food production.12