Marek's Disease

Agricultural Disaster Preparedness and Recovery May 29, 2013 Print Friendly and PDF

Marek's disease is a highly contagious disease of poultry caused by a herpes virus. The virus invades white blood cells and is shed in skin cells and dander. The disease is transmitted readily among chickens through direct contact with infected birds or through inhalation of contaminated dust. Although some birds can live with the infection, the mortality rate is high. There are four forms of the disease based on location of lesions: cutaneous (skin), neural (nerves), ocular (eye) and visceral (internal organs).


Where is the Disease Found?

Marek's disease is found worldwide.


Can the Disease Affect People?

Marek's disease is not a public health threat.


What are Signs of the Disease?

Signs of the illness can include any of the following:

  • Depression
  • Paralysis of leg(s) or wing(s)
  • Twisted neck
  • Discolored or irregularly shaped iris
  • Weight loss
  • Poor appetite
  • Diarrhea
  • Sudden death
  • Enlarged nerves and tumors, particularly associated with nervous tissue and ovaries, evident at necropsy


Can It Be Treated?

There is no specific treatment for Marek's disease. Any bird suspected of having Marek's disease should be reported to the State Veterinarians or USDA Area Veterinarian in Charge.


How Can the Disease Be Prevented?

A highly effective vaccine is available for Marek's disease. Hatcheries offer the option of purchasing chicks vaccinatined for Marek's Disease. This disease can be prevented by implementing a sound vaccination program and following the USDA-APHIS Biosecurity for the Birds program.


Where Can I Find Additional Information?

Marek's disease -Purdue University

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.