Egg Drop Syndrome (EDS) in laying hens

It is believed that the few infected hens carry latent virus and then infect other hens when they go into lay. Infected hens excrete virus and healthy hens in contact become infected. Once the flock becomes sick, horizontal contagion occurs, but the virus is not very infectious or excretion is low, so other nearby flocks may not become sick.

lthough the signs of EDS are quite characteristic, the diagnosis should not be made by the clinical picture alone, but should be confirmed by laboratory testing, as several infectious and non-infectious causes can lead to a decrease in egg production and can impair external and internal egg quality.

EDS and its consequences on production

Outbreaks of EDS typically last 4 to 10 weeks and a 10 to 40% drop in egg production can be expected. The time it takes for a bird to return to normal laying can be 4 to 8 weeks, and in many cases the production curve is below normal.

On the other hand, the virus is eliminated through the egg and day-old chicks, which makes it persistent in production. The spread of this type A adenovirus implies a greater number of affected birds during their productive stage, although it does not cause mortality.

EDS produces minimal lesions and they are limited to the reproductive tract of laying hens, where inactive ovaries, atrophy of the oviducts, and edema and white exudates in the uterus can be found.

Prevention of the Egg Drop Syndrome

There is no effective treatment for EDS. The prevention strategy should be based on a strict biosecurity plan, proper cleaning and disinfection of equipment in contact with eggs, especially egg trays, which are known to be a major factor in the spread of the disease, in addition to restricting the entry of visitors.