Systematic Veterinary Virology

SYMPTOMS

• The infection occurs in three forms classical, endaemic and sporadic. EDS affects only layers and breeders at the start of or during their egg production. Affected flocks show a failure to reach peak egg production or a drop in egg production accompanied by an inferior eggshell quality and in the case of brown eggs, a loss of shell color.
• Birds tend to eat the shell-less eggs, which therefore may be missed unless a search is made for the membranes. Affected birds may also appear to be anaemic, may show transient diarrhoea and sometimes the food intake may be reduced.
• No increased mortality or other symptoms are observed. Birds with antibody slow the spread of virus.  There is no effect on fertility or hatchability of those eggs suitable for setting. In cage units the virus spread isslow and the clinical signs are overlooked and the problem identified as a small depression (2-4%) of egg yield.