What is Egg drop syndrome?

Egg drop syndrome '76 is one of the important viral diseases of birds, notably chickens, ducks, geese and swans. It is characterised by a sudden drop in production of eggs as well as its eggshell quality in apparent healthy laying birds.

Previously, this disease was commonly named as merely "egg drop syndrome"; however, it is now recommended that full name, egg drop syndrome '76 , should be used to distinguish the name discrepancy from the recently identified disease in ducks caused by a flavivirus, which is confusingly called "egg drop syndrome in ducks" or "duck egg drop syndrome".