Pathology - Birds

Birds

Marek's disease

Figure 1: Left: Normal chicken eye; Right: diseased eye with grey iris and irregular pupil
Source: United States Department of Agriculture (2014) Cracking the Code of Marek's Disease, Available at: http://www.ars.usda.gov/is/AR/archive/jul01/marek0701.htm (Accessed: 3rd June 2014).

Marek's disease, leg paresis, chicken 

Figure 2: Chicken with leg paralysis.
Source: Gimeno I.M. (2008) 'Marek's disease vaccines: a solution for today but a worry for tomorrow?' Vaccines, 26, pp. C31-C41.

  • Highly cell-associated avian Alphaherpesvirus
  • Respiratory tract of birds = natural entry of virus
    • Inhaling of free virus in feather follicles in shed 
  • Clinical signs:
    • Neurological clinical signs
      • Paralysis of legs, wings and neck
    • Lymphoid tumours in visceral organs
      • Heart, lungs, ovaries, testes, muscles
    • Tumours in feather follicles
    • Grey iris or irregular pupil
    • Nerve lesions leading to visual impairment
  • Some vaccines:
    • Serotype 3
    • Serotype 2
    • Attenuated serotype 1
Avian Pox


Figure 3: Sentinel domestic turkey with increasing severity of avian pox. Cutaneous lesions and tumours are observed on the eye. 
Source: Thomas N.J., Hunter B. and Atkinson C.T. (2008) Infectious diseases of wild birds, 1st edn., USA: Blackwell Publishing Professional.
  • Skin disease
  • Transmitted directly between host individuals environmentally or mechanically by biting arthropods:
    • i.e. MOSQUITOS!
  • Susceptilibity of individuals determine transmission
  • Clinical signs:
    • Localized tumours in non feathered areas of skin
    • Lesions occur on beak, feet, claws
    • Begin as white /yellow foci and increase in size rapidly
    • Impair vision:
      • Tumours on eyelids
      • Conjunctival proliferation
      • Blepharitis
    • Sudden death
    • Sudden dyspnea
    • Upper respiratory tract disease
    • Pneumonia
    • Airsacculitis
    • Splenomegaly
  • Treatment:
    • Supportive therapy i.e. saline
    • Lesions heal in 4 weeks
    • Surgery to remove tumours may help
    • Vitamin supplementation
    • Immunostimulant
    • Anti-inflammatory drugs
    • Anti-microbial therapies
References
  1. Gimeno I.M. (2008) 'Marek's disease vaccines: a solution for today but a worry for tomorrow?' Vaccines, 26, pp. C31-C41.
  2. Mao W., Kim T. and Cheng H.H. (2013) 'Visualization of Marek’s disease virus in vitro using enhanced green fluorescent protein fused with US10', Virus genes, 47, pp. 181-183.
  3. Raidal S.R. (1995) 'Viral skin diseases of birds', Seminars in Avian and Exotic Pet Medicine, 4(2), pp. 72-82.
  4. Thomas N.J., Hunter B. and Atkinson C.T. (2008) Infectious diseases of wild birds, 1st edn., USA: Blackwell Publishing Professional.
  5. United States Department of Agriculture (2014) Cracking the Code of Marek's Disease, Available at: http://www.ars.usda.gov/is/AR/archive/jul01/marek0701.htm (Accessed: 3rd June 2014).
  6. Zylberberg M., Lee K.A., Klasing K.C. and Wikelski M. (2012), 'Increasing avian pox prevalence varies by species, and with immune function, in Gal√°pagos finches', Biological Conservation, 153, pp. 72-79.