Egg Drop Symdrome ’76 (EDS ’76)


EDS '76 is one of the most common viral diseases in birds, notably chickens, ducks, geese and swans. It is characterized by a sudden drop in production of eggs as well as its eggshell quality in apparent healthy laying birds. In the autumn of 1976 a distinct egg drop syndrome was first identified in Northern Ireland. It affects chickens and has occurred in Ireland, Holland, France, England, Germany, Spain, Peru, Brazil, Uruguay, Argentina and the same symptom has been found all across the globe. Mortality is usually negligible.


EDS '76 is caused by double stranded-DNA virus, called Duck Atadenovirus A (formerly knows as Duck Adenovirus A). The diameter of the virus is between 70 and 80 nm by negative staining. The other name of this virus may include duck adenovirus 1 (DAdV-1), EDS '76 virus (EDSV) and adenovirus 127 (AV-127).


  • The disease usually occurs on laying hens and breeding roosters. The onset time is from 26th to 40th week, which is also laying period.
  • EDS ’76 can be found in all kinds of poultry and waterfowl. The incubation period is 7 to 9 days and in some cases, may cause illness after 17 days of infection.
  • Infections can be passed on from layers to eggs and the virus can be spread in the rearing area through infected eggs.


EDS ’76 can last for 6 - 12 weeks with typical symptoms such as:

  • Can caused transient and intermittent diarrhea during infection period, antibiotics may be administered during this period but effect will be minimal.
  • Although it has been shown experimentally that eggs usually continue to be produced at a normal rate (so the disease name may be a misnomer), the number of useable eggs produced falls by 10%–40%.
  • Transient mild depression and/or mild watery droppings may be noted.
  • Production of pale-shelled eggs, quickly followed by production of soft-shelled and shell-less eggs.


There is no treatment for EDS ’76. Vaccination is the best way to deal with this disease and vaccines are advised to be given to flocks around 15 to 16 week-old for maximized effect.

Also during the prevention of the disease, it is recommended to implement these steps:

Step 1: Use of dedicated equipment and egg trays for each farm, and/or washing and disinfecting plastic egg trays before use, can help to control the endemic form. The sporadic form can be prevented by separating chickens from other birds, especially waterfowl. General sanitary precautions are indicated, and potentially contaminated water should be chlorinated before use.

Step 2: Strictly follow vaccination schedule on laying hens when they reach 15 – 16 weeks of age.

Step 3: Regularly apply adjuvants to enhance natural resistance such as:

VITA B-COMPLEX +K3 +C: Enhances fertility, enlarges eggs and develop sexual organs.

VITASTRONG: Supplements of vitamins, essential minerals and enzyme, specially formulated for poultry.

CALZIPHOS PLUS: Supplements of rare minerals which helps preventing polio, thick white egg shell symptoms.  



Know-How, Poultry