Marek’s disease in Poultry

Dr. Sandeep Marodia – Apollo College of Veterinary Medicine, Jaipur

Rohitash Kumar – PIGVER, Jaipur

Introduction:

Marek’s disease is one of the most common viral lymphoproliferative and highly contagious disease affecting poultry populations worldwide. Mainly it affects the nervous system and causes tumors in the major internal organs of chickens. The disease presents typically between 12 and 20 weeks of age and is usually fatal. This disease may also affect turkeys, pheasants, quail and game birds but is less common.

Etiology:

Marek’s disease is caused by avian Herpes virus (alpha-herpes virus) which is a double stranded DNA virus. This virus is widely distributed in chickens all over the world.

Mode of Transmission:

Marek’s disease is highly contagious and spreads quickly between birds. The Marek’s disease virus resides in the feather follicles and can be shed into the environment. Healthy birds mainly acquire infection through respiration when birds breathe in infected dust and dander. Vertical transmission of this disease is not considered to be important.

Clinical manifestations of Merek’s disease

• Paralysis of legs, wings and neck.
• Loss of body weight.
• Grey colour iris or irregular pupil.
• Vision impairment.
• Skin around feather follicles raised and roughened.

Post-mortem lesions

• Grey-white foci of neoplastic tissue in liver, spleen, kidney, lung, gonads, heart, and skeletal muscle.
• Thickening of nerve trunks and loss of striation.
• Microscopically – lymphoid infiltration is polymorphic.

Treatment of Marek’s Disease:

• There is no specific treatment for Marek’s disease.
• Because of lack of specific treatemnt, the chicken community has focused on preventing it instead.

Prevention of Marek’s Disease:

• Good sanitation and ventilation should be adopted.
• Brooder chicks should keep separate from adults until 5 months of age.
• Vaccination should be done in all day old chicks.
• Since the control of the disease is difficult so you need a good understanding of the basic principles in order to reduce the chance of your birds becoming infected.