Egg drop syndrome ( EDS-76) :

• It may defined as a sudden drop in egg production or a failure to achieve a normal peak in production
• It affects chickens worldwidely
• Mortality is usually negligible

Etiology :

• The disease is caused by a virus belonging to the subgroup III of Avian Adenovirus ( strain BC14, virus 127) , the EDS virus does not belong to any of 12 fowl Adenoviruses

Transmission :

• Transmitted through egg to a few birds in flock ; these birds carry virus until the flock comes into lay at which time they begin to excrete virus and infects birds kept in some houses
• Horizontal spread through infected litter and does occur once a flock shows disease but it seems that virus is not very infectious or level of excretion is low

Clinical signs :

• It affects only layers and breeders at the start or during their egg production
• Affected flocks show a failure to reach peak egg production accompanied by an inferior egg shell quality and in case of brown eggs, loss of shell colour
• Anaemic
• Diarrhoea
• Food intake is reduced
• Loss of shell quality

Postmortem lesions :

• No specific lesion – only a slight atrophy of ovary and oviduct
• Histopathology – degenerative changes in epithelial cells of magnum of oviduct

Fig :  A; normal hens’ reproductive system B; inactive ovaries and shrunken oviducts

Diagnosis :

• History
• Signs and lesions( mostly lack of )
• Isolation and identification of virus
• Serology : HI , ELISA

Differential diagnosis :

• Infectious bronchitis
• Newcastle disease
• Infectious laryngotracheitis