Avian Encephalomyelitis Egg Drop in ...

Avian Encephalomyelitis Egg Drop in Laying Hens


Avian Encephalomyelitis Egg Drop in Laying Hens

Avian Encephalomyelitis in laying hens experiences a temporary drop in egg production about 5-10% and last for 5-14 days, with the return to full potential production at the end of this time. There is no loss of eggshell quality. (1, 2, 3, 4)

In breeders, hens, the fall in hatchability accompanying the depression in production is about 5% of fertil eggs and there is a serious disease in the progeny. (1, 2, 3, 4)

Observed Clinical Signs Happenings

Egg Drop

  • Egg production declines rapidly
  • Mature birds may experience a temporary drop in egg production (5-10%)  and lasting no more than 2 weeks (5-14 days), with a return to full potential  production at the end of this time, but do not develop neurologic signs

Avian Encephalomyelitis Egg Drop in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  1. Egg production drops gradually
  2. Mortality above the standard
  3. Visibly sick birds
  4. Flock behavior activity change
  5. Droppings abnormalities
  6. Respiratory abnormalities
  7. Neurological Nervous
  8. Lameness or unusual movements, incoordination, ataxia
  9. Eyes abnormalities
  10. Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Ear lobes, abnormalities (except eyes)
  11. Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression
  12. Feathers abnormalities
  13. Feed Consumption Changes
  14. Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, Another feed brand)
  15. Shell quality defects
  16. Internal Egg defects


Causing Agents
Viral disease. Virus (Picornaviriade family). It has been tentatively placed in the genus Hepatovirus. (Year 2000).
Affected Systems/Organs
Reproductive System
Via the oral infection route. Contaminated feaces, environment, feed, water and equipment
Mainly Affects
Egg production
Vaccination Programs, Good Hygiene and Biosecurity practices.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Can be managed with vaccination programs
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


  1. David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 488
  2. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 433
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. page 352
  4. Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition. page 76

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