Avian Hepatitis E Virus Infections, ...

Avian Hepatitis E Virus Infections, or Big Liver and Spleen Disease, or Hepatitis Splenomegaly Syndrome in Laying Hens

Avian Hepatitis E Virus Infections, or Big Liver and Spleen Disease, or Hepatitis Splenomegaly Syndrome in Laying Hens

Observed Clinical Signs Happenings

Egg drop

  • Egg production drops gradually
  • Drop in egg production may be the first indication of infection in a flock, lasting for up to 3—4 weeks.
  • Failure to attain peak production may be the first sign
  • Egg drop may reach 20% and accompanied by up to 1% mortality per week
  • Egg production may be affected, usually (usually 4-10%)
  • In other outbreaks, egg production has not been affected

 Visibly sick birds

  • Few visibly sick birds
  • Morbidity and mortality in the field are relatively low
  • Affected birds show depression
  • Soiled vent feathers or pasty droppings
  • Pale combs and wattles

Mortality

  • Low mortality or increases gradually
  • Morbidity and mortality in the field are relatively low
  • Weekly mortality increases to approximately 0.3%  for several weeks
  • Sometimes mortality reach 1% mortality per week over a period of 3-4 weeks
  • Highest incidence occurring between 40-60 weeks of age
  • Hepatitis Splenomegaly Syndrome is characterized by above-normal mortality of 30-72 weeks of age

 

 Dead Birds

  • Prior to death, affected birds are usually in good bodily condition with pale combs and wattles
  • Sometimes the dead bird is in poor bodily condition

Head Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes

  • Pale combs and wattles

Droppings

  • Soiled vent feathers or pasty droppings
  • Feces smeared on feathers around the vent
  • Dirty or Pasty vents or feathers with droppings around the vent

Feathers

  • Soiled vent feathers or pasty droppings
  • Feces smeared on feathers around the vent
  • Dirty or Pasty vents or feathers with droppings around the vent
  • Induce a moult
  • Many birds in the flock may exhibit loss of primary feathers resembling moulting.
  •  Moult primary feathers (premature moulting)

Egg quality

  • Egg size decreased or reduced
  • Pale or loss of colour in brown-shelled eggs
  • Small eggs with thin and poorly pigmented shells
  • Small eggs
  • Smaller than normal Eggs
  • Thin-shelled and soft-shelled or porous eggs
  • Ungraded or second's eggs increased
  • Egg specific gravity score lower (should be above 1.080 (1.068 thin shells)

 

Avian Hepatitis E Virus Infections, or Big Liver and Spleen Disease, or Hepatitis Splenomegaly Syndrome in Laying Hens show, exhibit, or manifest any of the following clinical signs happenings:

Observed Clinical Signs Happenings*

ALWAYS

NEVER

SOMETIMES

Egg drop

  •  

 

  • *

Egg production declines rapidly

 

  •  

 

Egg production drops gradually

  •  

 

 

Mortality above the standard

  •  

 

 

Low mortality or increases gradually

  •  

 

 

High mortality or increases rapidly

 

  •  

 

Dead birds

  •  

 

 

Dead birds in Good bodily condition

 

  •  

 

Dead birds in Poor bodily  condition

  •  

 

  • *

Visibly sick birds

  •  

 

 

Few visibly sick birds

  •  

 

 

Many visibly sick birds

 

  •  

 

Flock behaviour activity change

  •  

 

 

Droppings abnormalities

  •  

 

 

Respiratory abnormalities

 

  •  

 

Neurological Nervous

 

  •  

 

Lameness or unusual movements, incoordination, reluctance to move

 

  •  

 

Eyes abnormalities

 

  •  

 

Head: Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes (except eyes)

  •  

 

 

Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression

 

  •  

 

Feathers abnormalities

  •  

 

 

Feed Consumption Changes

 

  •  

 

Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)

 

  •  

 

Shell quality

  •  

 

  • *

Internal Egg quality

 

  •  

 

*  Sometimes has not been observed  these clinical signs yet or inadequacy of monitoring systems, and even the course time of the disease

*In other outbreaks, egg production has not been affected

*Sometimes has not been observed or measured the shell quality changes yet or inadequacy of monitoring systems, and even the course time of the disease

 

 

Causing Agents
Viral Infection. Avian Hepatitis E virus infection. Herpesvirus.
Affected Systems/Organs
Reproductive, Digestive system. Liver and Spleen.
Spread
Natural infections have only been demonstrated in birds over 24 weeks of age though it is possible that transmission from parents and/or infection in rear occur with a subsequent period of latency.
Mainly Affects
Egg Production, Egg Quality and Liveability
Solution
Trough cleaning and disinfection after depletion of an affected flock. Good biosecurity. All in/all out production.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Can be dealt with in house
  • Technical assistance recommended
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality

1

Impact on Liveability

1


Impact on Production

1

Overall Economic Impact

1



  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 444
  2. David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 496
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. 413

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