Egg Drop Syndrome

Egg drop syndrome is a disease that is viral in nature. It affects egg production and is usually accompanied by a reduction in egg quality.

The birds that it infects do not show any outward signs of being ill other than their eggs having very soft shells or even having eggs without shells.

The cause of the disease is duck adenovirus A, which is naturally occurring in ducks and geese. 

It is the common belief in the scientific community that the initial outbreak in chickens occurred when a contaminated Marek's disease vaccine grown in duck embryo fibroblasts was sent out into the population. 

The virus infected the breeding flocks and was then spread to other flocks through infected eggs. 

Rare outbreaks of EDS can occur by virus transmission directly from ducks and geese to a chicken flock through direct contact or from contaminated water.

Although EDS has not affected birds in the U.S., it has been considered a serious problem at times in Europe and in South America.

Countries that have had outbreaks include:

  • Ireland
  • Holland
  • France
  • England
  • Spain
  • Germany
  • Europe
  • Peru
  • Brazil
  • Uruguay
  • Argentina
  • Contamination of egg trays at packing stations have played a major part in the spread of the disease.

    Here are some of the common signs of chickens infected with EDS:

  • Drops in egg production from 5 percent to 50 percent at the time of peak egg production
  • Thin or soft shelled eggs or even eggs without shells
  • Loss of shell color
  • Poor internal quality to eggs
  • The birds producing the bad eggs will not appear to be sick
  • What other diseases does EDS appear like?

    The eggs quality and drop in egg production can sometimes be associated with Newcastle disease and some influenza virus infections such as Avian Influenza.

    It can be distinguished from these diseases by the absence of sickness in the birds. Birds infected from either of these will show symptoms of sickness.

    Infectious Bronchitis can also be similar to egg drop syndrome.

    You can distinguish a difference in these diseases by examining the eggshell changes that occur. There will be an absence of ridges and malformed eggs that are sometimes seen with infectious bronchitis.

    Is there a treatment for EDS?

    There is not a treatment, but there are preventative maintenance methods that should be followed.

    Some management problems that could have occurred include:

  • Inadequate water supply
  • Extremes in temperature
  • Inadequate lighting
  • Sudden changes in a feeding program
  • Quarantine and disinfection is also necessary as the virus is contagious by either direct or indirect contact. The virus can also be transmitted vertically as both the interior and exterior of the egg contain the virus.

    Adenoviruses can be resistant to many commonly used disinfectants. Check with your local agricultural experts to make sure that you are using the right disinfectants for the job.

    Egg drop syndrome is also a disease that must be reported in most places in the world. Report immediately to state and federal authorities upon diagnosis or even if the suspicion of egg drop syndrome arises.

    If you have questions that you would like to ask a vet, use the service below. Ask a Vet has qualified doctors that can answer questions about chicken health.

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