Egg Drop Syndrome (EDS)
Egg drop syndrome is an infectious disease of laying hens caused by a hemagglutinating adenovirus and characterized by thin shelled and shell less eggs in otherwise healthy birds.
Note soft shelled or thin shelled eggs are usually caused by a lack of calcium in the diet that oyster grit and shell will naturally correct.
The natural hosts for EDS virus are ducks and geese, but has become a problem with chickens of all ages.
The disease is most severe in broiler breeders and brown egg layer strains, less so in white egg breeds.
EDS was first introduced into chickens through contaminated vaccine. Transmission occurs by any of the conventional methods of disease spread. Infected birds excrete the virus in the feces. Vertical transmission is considered the primary mode of spread.
Clinical signs are loss of colour in pigmented eggs, followed by thin shelled or shell less eggs. Egg production drops by 40 percent. Virus isolation should be done in duck or goose embryos or cell cultures of duck or goose origin. Harvested allantoic fluid or cell culture should be checked for hemagglutinating activity in chicken RBC.
There is no successful treatment. The endemic form in breeders can be controlled by washing and sanitizing incubators and egg trays before reuse. In layers, molting will restore egg production. Prevention is through the control of vertical transmission. Endemic EDS is associated with the egg-packing stations, as contaminated egg trays can be a major factor in spread. Virus is also present in fecal material, so hygienic procedures are required.