Avian Hepatitis E Virus Infections, ...

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

Hepatitis-splenomegaly (HS) syndrome is a disease of layer and broiler breeders characterized by increased mortality and decrease of egg production and is primarily caused by avian hepatitis E virus.

Morbidity (percentage of sick birds) and mortality in field are relatively low, although subclinical avian infections are widespread in chicken flocks.

In some outbreaks, there has been a drop in egg production of up to 20%, but in other outbreaks, egg production has not been affected.

HS syndrome is characterized by above-normal mortality of 30-72 weeks of age, with the highest incidence occurring between 40-50 weeks of age. Weekly mortality increases approximately 0.3% to 1.0% for several weeks (3-4 weeks).

Diseased birds may have pale combs and wattles, depression, anorexia, and soiled vent feathers or pasty droppings. Small eggs with thin and poorly pigmented shells. Internal qualities are unaffected.

Causing Agents
Viral Infection. Avian Hepatitis E virus infection. Herpesvirus.
Affected Systems/Organs
Reproductive, Digestive system. Liver and Spleen.
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
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


Impact on Liveability


Impact on Production


Overall Economic Impact


Y.M. Saif.2008.Disease of Poultry. 12th Edition.

Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.

Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition.

Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.

Donald D. Bell, Williams D. Weaver. 2009.  Commercial Chicken Meat and Egg Production. Fifth Edition.

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