Egg drop syndrome (EDS) is characterized by production of soft-shelled and shell-less eggs in apparently healthy birds. It has been recognized worldwide, except in the USA. It replicates well in chick kidney or chick-embryo liver cells and to a lesser degree in chick-embryo fibroblasts. The natural hosts for EDS virus are ducks and geese, and the disease has been described in Japanese quail ( Coturnix coturnix japonica ). Three types of disease are recognized in chickens. Classical EDS probably was due to contamination of a vaccine for Marek’s disease grown in duck-embryo fibroblasts and subsequent adaptation of the virus to chickens. Basic breeding stock was infected, and the virus was transmitted vertically through the egg. The virus often remained latent until the chick reached sexual maturity, when it was excreted in the eggs and droppings to infect susceptible contacts. Because the virus is vertically transmitted and is reactivated around peak egg production, there was an apparent breed and age susceptibility. However, all ages and breeds of chickens are susceptible, although the disease tends to be most severe in heavy broiler-breeders or brown egg producers. Arising from the classical form, endemic EDS has been reported in many areas and is usually seen in commercial egg producers. Flocks become infected at any stage in lay. Contaminated egg collection trays are one of the main forms of horizontal transmission, and outbreaks are often associated with a common egg-packing station. 

Egg Drop Syndrome Antibody Test Kit is used for quantitative detection of antibodies against Egg Drop Syndrome virus (EDS) in chicken serum and yolk. 
Inactivated antigen is bound to a microwell. Diluted sera is added to the microwell and incubated. Any anti-EDS antibodies present in the serum will bind to the EDS on the microwell forming an EDS antigen-antibody complex. After washing away any unbound material, anti-Chicken IgG Alkaline Phosphatase conjugate is added to the microwell. The conjugate will bind to the EDS antigen-antibody complex. After incubation any unbound conjugate is removed by washing. Enzyme substrate is then added to the microwell. The substrate reacts with any Alkaline Phosphatase present and forms a yellow product. In the final step the reaction is stopped, fixing the color. The intensity of the color is measured photometrically at 405 - 410 nm with a 630-650 nm reference filter.