Avian Influenza Low Pathogenic (LPA ...

Avian Influenza Low Pathogenic (LPAI) Mildly Virulent in Laying Hens

Avian Influenza Low Pathogenic (LPAI) Mildly Virulent in Laying Hens

The mildly virulent clinical group results from infection by low pathogenic avian influenza (LPAI) virus with low mortality and mild respiratory disease or drops in egg production. Mortality is usually less than 5% and is typically in older birds. (1, 2)

Observed Clinical Signs Happenings

Egg Drop

  • Egg production declines gradually

Visibly sick birds

  • Few visibly sick birds
  •  In some instances or sometimes it is difficult to find visibly sick birds


  • Low mortality or increases gradually
  • Mortality is usually less than 5% and is typically in older birds

Dead birds

  • Skinny body (Poor body fleshing condition)


  • Mild respiratory disease
  • Respiratory signs spread slow or fast
  • Coughing
  • Sneezing
  • Rales
  • Rattles

Avian Influenza Low Pathogenic (LPAI) Mildly Virulent in Laying Hens in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  1. Egg production declines rapidly
  2. High mortality or increases rapidly
  3. Dead birds: Good body fleshing condition
  4. Flock behaviour activity change
  5. Droppings abnormalities
  6. Neurological Nervous
  7. Lameness or unusual movements, incoordination, ataxia
  8. Eyes abnormalities
  9. Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Earlobes, abnormalities (except eyes)
  10. Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression
  11. Feathers abnormalities
  12. Feed Consumption Changes
  13. Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, Another feed brand)
  14. Shell quality defects
  15. Internal Egg defects
Causing Agents
Viral infection (Influenza virus Orthomyxoviridae), genus Influenzavirus A Avian Influenza Low Pathogenic (LPAI) Mildly Virulent
Affected Systems/Organs
Respiratory and reproductive systems
Bird to bird, contaminated water and objects from infected birds. The virus is transmitted by direct contact between infected and susceptible birds or indirect contact through aerosol droplets or exposure to virus-contanminated fomites. The virus is excreted from the nares, mouth, conjunctiva, and cloaca of infected bird into the environment because the virus replication in the respiratory, intestinal, renal, and/or reproductive organs.
Mainly Affects
Liveability and egg production
Biosecurity and hygiene programs and an 'All-in/All-out' approach to production. Vaccination with Inactivated H5 and H7 vaccine and a fowl pox-AI hemagglutinin (H5) recombinant vaccine (rFP-AI-H5).
Suggested Actions
  • Can be managed with vaccination programs
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended
  • Can be managed with vaccination programs.
  • This is a notifiable disease, veterinary intervention is essential. It is advisable that you run DTECT again to ensure you have answered all the questions correctly. If you suspect that you may have this disease please contact your local authorities immediately.

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 167
  2. David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 196
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.
  4. Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition.
  5. Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
  6. Donald D. Bell, Williams D. Weaver. 2009.  Commercial Chicken Meat and Egg Production. Fifth Edition.

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