Epidemiological studies with egg drop syndrome-1976 (EDS-76) virus.

The epidemiology of egg drop syndrome-1976 (EDS-76) virus has been investigated under experimental conditions and in the field. Quantitative experimental studies indicated that the rate of virus spread from infected to in-contact chickens depended on the amount of challenge, being more rapid when the number of infected chickens in a group of susceptible ones was greatest. In field studies, lateral spread of EDS-76 virus was demonstrated in a primary breeding flock and in a flock of commercial layers. In the latter the virus was recovered from cloacal swabs from chickens up to 45 weeks of age. On the basis of specific serological responses, infection took approximately 11 weeks to spread through a row of 80 battery cages in a house 112 feet long.