Marek's disease (MD)

Marek‘s disease is caused due to herpes virus, which is tumor causing viral disease of chickens, characterized by marked enlargement of nerves, liver, spleen and kidney due diffuse growth of certain cells. Once a bird infected in life, and remains infected until death. This disease has to high economic importance because of heavy mortality.

Transmission involves infected bird (feather follicle), airborne, fomites and visitors but not through egg transmission.

Symptoms depend on involvement of nerve i.e. brachial and sciatic nerve causes paralysis of the wings and legs. A characteristic posture i.e. one leg forward and another leg backward. Other symptoms include torticollis, enlargement of liver, spleen and kidney. Post mortem finding includes affected nerves are up to 2-3 times the normal thickness.

Disease can be controlled by Vaccination on day old, isolation of affected bird, selection of genetically resistant stock and biosecurity measures. Antimicrobials are required to control the secondary bacterial infections. Measures to boost the immune system of the birds will hasten the recovery.