Marek’s disease (MD) till 1963-64 was considered under Avian leucosis complex. As in many other countries, in India also this disease has reached at a dangerous level resulting in yearly loss of over Rs. four crores through mortality. Considering economic loss duo lo morbidity in addition to morbidity it can be well visualized.
It is not transmitted trough egg but it is highly contagious and spreads principally by way of air saliva, nasal washing, feather follicle and faeces from infected birds.
The disease affects the birds in the age group 6 to 10 weeks and may continue even in laying bird though less in .severity. II generally occurs in two forms: Acute forms-cause sudden death of the affected birds with present of visceral tumors inside the body.
Characterized by bilateral or unilateral paralysis of legs, wings or neck due to enlargement of various nerves inside the body, besides these two typical forms, there are other manifestation of the disease such as blindness and skin tumors.
Immunization has been found to be effective. Recently Herpes Turkey Virus (HTV) vaccine manufacturers in India have been introduced for field trials. There are following immunization procedures:
Turkey’s help virus.
Attenuated virulent MD virus strains.
Naturally occurring mild strains.
Chicken’s blood containing mild MD agent but free from other agents. HTV vaccine is most effective and relatively free of problems
Three approaches are being practiced to control Marek’s disease
Breeding stock resistance to M.D.
Maintaining; birds under strict isolation,
Usa of preventive vaccines.