Marek’s Disease

Marek’s Disease (MD) is a highly contagious viral disease caused by an alphaherpesvirus. It primarily affects chickens but can also occur in turkeys and other birds. The disease is characterized by the development of lymphoid tumors in various organs and tissues.

SYMPTOMS
CAUSES
PREVENTION
TREATMENT

Symptoms

  • Chickens (Most Common):
    • Paralysis of legs, wings, and neck
    • Vision impairment or blindness
    • Weight loss and poor growth
    • Pale or irregular comb/wattles
    • Internal tumors
    • Skin lesions
    • Respiratory distress
    • Depression and lethargy
  • Age-specific manifestations:
    • Young birds (12-30 weeks): Most susceptible
    • Adult birds: Lower mortality but reduced productivity

Causes and modes of transmission

  • Viral Characteristics:
    • Herpesvirus (Gallid herpesvirus 2)
    • Highly resistant in environment
    • Multiple strains varying in virulence
  • Transmission Routes:
    • Airborne through contaminated dust/dander
    • Direct contact with infected birds
    • Contaminated equipment and facilities
    • Vertical transmission (not through egg)
    • Infected feather follicles

Prevention strategies

  • Vaccination:
    • Day-old chick vaccination essential
    • Different vaccine types available
    • Proper storage and administration crucial
  • Biosecurity:
    • Isolation of age groups
    • Strict cleaning protocols
    • Controlled access
    • All-in-all-out systems
    • Proper ventilation
    • Regular disinfection
  • Management:
    • Stress reduction
    • Good nutrition
    • Clean environment
    • Proper stocking density

Treatment options

  • No specific treatment available
  • Management approaches:
    • Supportive care
    • Good nutrition
    • Clean environment
    • Isolation of affected birds
    • Culling may be necessary

Conclusion: Regular monitoring and adaptation of control strategies are essential as virus strains continue to evolve.