2023-09-08
What is the cause?
EDS is caused by an adenovirus known as duck adenovirus 1, or egg drop syndrome virus (EDSV).
This is not to be confused with the recently described flaviviral disease of ducks, which has been referred to as “duck egg drop syndrome”. Although the first isolates of EDSV were from chickens, it has since been discovered to have originated from ducks. EDSV is now considered a naturally occurring virus in waterfowl. All virus isolates belong to the same serotype of duck adenovirus type 1 (DAdV-1). Recent studies suggest that the virus circulating in chickens has not significantly changed since it was initially introduced.
EDS in the field
EDS can spread vertically and horizontally. Vertically, the disease can be transmitted from the parent to the eggs that are hatched. Inside the egg, this virus has infected the chicken's body, but is still in a temporary unconscious (dormant) state. Until it's time for the chicken to enter the production period, the virus will be active and affect the productivity of the chicken until it hatches its new eggs.
Then for horizontal transmission, it can be caused by direct contact of infected chickens with other chickens. The environmental conditions of the houses, equipment, and the traffic of livestock products as well as the traffic of people going in and out of the houses is also an access for the spread of this virus horizontally from one place to another. In addition, it is not uncommon for breeders to 'miss' in anticipating this disease attack. EDS cases in the field do not show specific clinical symptoms, so farmer are often 'missed'. Apparently, the chicken had been infected with the EDS virus and spread the virus through feces. When chickens have been attacked by this disease, a decrease in production will occur.
The decline in chicken production has had a huge impact on breeders and layers. The reason is, this disease can result in a decrease in production of between 20 – 50%, which is economically very detrimental. EDS disease usually attacks chickens aged 25 – 30 weeks, which is when chickens should reach their peak production. Apart from that, chicken eggs with EDS will experience a decrease in physical quality, ranging from pale eggshells to eggs without shells. This means that the eggs cannot be distributed for sale. The decrease in egg production and quality due to EDS can last for 6-8 weeks.
The incidence of Egg Drop Syndrome (EDS) in the field is not very high, but it can still be found in the field. Several countries such as Indonesia, Malaysia, Cambodia, Vietnam, India, Pakistan can still find EDS cases even though the incidence is not too high. Generally, farmer really understand how to deal with this disease. Of course, with good management practices and routine vaccinations. PT. Medion Farma Jaya has a vaccine that contains EDS in combination with several other diseases, namely Medivac NDG7 – EDS Emulsion, Medivac NDG7 – EDS – IB Emulsion, Medivac ND – EDS – IB Variant Emulsion which can be used before the chickens enter the production period (15-17 weeks old).
When compared, the diagnosis of EDS is similar to Avian Influenza (AI), Infectious Bronchitis (IB), and Newcastle Disease (ND). This is because these three diseases show a decrease in egg production accompanied by damage to the appearance of the eggs. In order to confirm the diagnosis of EDS, various methods have been developed in the field to identify this disease, such as serological tests such as the Hemagglutination (HA) / Hemagglutination Inhibition (HI) Test, Enzyme-Linked Immunosorbent Assay (ELISA), and Polymerase Chain Reaction (PCR).
How to control?
As we know that there is no treatment for EDS, but we can do prevention and management improvement.
• Obtain replacement birds from uninfected flocks.
• Practice good cleaning and disinfection protocols, particularly concerning materials that contact eggs and common egg-packing stations.
• Do not reuse egg trays or share egg trays with other farms.
• Change needles frequently during vaccination and blood collection.
• Take precautions in the hatchery when dealing with infected and uninfected flocks to prevent lateral transmission. Minimal precautions would be to use separate setters and hatchers and to handle clean stock prior to handling infected chicks.
• Follow a biosecurity program, with emphasis on exclusion of waterfowl and wild birds as well as appropriate water sanitation.
• Endemic EDS can be controlled by vaccination using a commercially available inactivated vaccine administered intramuscularly between 14–18 weeks of age.
• Autogenous vaccines can be used where the commercial vaccine is not available to prevent additional spread.
Dr. Yonatan Dimascahyo Budianto, DVM, MSc, MM, MBA
Technical Education and Consultation
Artha Vena International Pte. Ltd
