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Egg Drop Syndrome

Egg Drop, EDS

Egg drop syndrome (EDS) is a disease affecting domestic laying hens, caused by an atadenovirus. The virus is believed to have originated in ducks and other waterfowl, who are often infected with the virus but show no clinical signs of disease. Heavier broiler-type breeds and brown egg producing chickens are most severely affected by the disease.

Symptoms of Egg Drop Syndrome

Often, the first sign of infection is a change in the color of the egg, quickly followed by production of smaller-the-normal eggs, shell-less, thin-shelled, or soft-shelled eggs, and either a rapid or extended loss in egg production of up to 40%. Clinical signs are mainly associated with egg production.

Diagnosis of Egg Drop Syndrome

The sensitivities of various serologic assays, including agar gel precipitin (AGP) assay, ELISA, Hemagglutination-inhibition (HI), and serum neutralization, are similar for detecting antibodies to EDS virus.

Clinical Signs

Change in egg color
Soft-shelled eggs
Shell-less eggs
Decreased egg production
Smaller-then-normal eggs


  • History
  • Clinical signs
  • Viral isolation


No treatment is generally required unless secondary reproductive-related complications arise.



  • Biosecurity
  • Vaccine. Inactivated vaccines with oil adjuvant are available and, if properly made, control the disease. They reduce but do not prevent virus shedding.

Scientific References

Risk Factors

  • Keeping ducks and other waterfowl together with laying hens.
  • Limit exposure to wild waterfowl.