An adenovirus, responsible for egg drop syndrome, has been diagnosed in broiler breeder flocks based on both PCR assay and serology. Flocks supplying a Midwest complex demonstrated an asymptomatic acute decline in production with the presence of pale-colored shells with decreased integrity and ultimately shell-less eggs. According to a report presented at a recent meeting there was no epidemiologic evaluation of the outbreak or an indication of how the infection entered the farm.

Based on experience in Europe and Asia, infection in integrated broiler operations is usually introduced onto parent farms on contaminated egg-gathering material including flats and incubator racks. The infection can remain dormant in rearing pullets resulting in interruption in ascendency to peak or a drop in production of 20 to 40 percent shortly thereafter. Recovery to standard hen week production usually occurs within four to six weeks but a flock can lose 30 settable eggs per hen during the first half of a production cycle. Since the infection continues to circulate in a complex or region preventive vaccination is required. Inactivated vaccine was imported from the E.U. under special license to protect pullets reared for small contract laying flocks in Indiana and Ohio. Depending on incidence rate and regional occurrence in coming months it will be necessary to initiate local manufacture of commercial vaccines to supplement autogenous products.

As a side issue of relevance, a recent industry periodical posted a report on the condition and included an image of eggs that was grossly misleading.  The wrinkled egg observed in their illustration is more consistent with infectious bronchitis. This egg was surrounded with normal brown-shelled presumably table eggs showing deep brown pigmentation. Flocks affected with egg drop syndrome produce shells that are generally devoid of pigment and are markedly reduced in density.