Egg drop syndrome isn’t widespread in the United States, but it has caused problems for some Pennsylvania egg farms in recent years.
“When we first saw it, we said, ‘Nope, doesn’t occur in the U.S.’ And sure enough, it did,” said Dr. Sherrill Davison, an avian pathologist at the University of Pennsylvania School of Veterinary Medicine.
Davison spoke Oct. 29 at the Egg Industry Issues Forum presented by the Egg Industry Center.
Egg drop syndrome was first described in the Netherlands in 1976.
Most of the U.S. cases have been in Indiana and Pennsylvania. The disease mostly affects brown birds, and it combines shell quality problems with a drop in egg production.
Those symptoms can also be caused by avian influenza, so the lab must rule out that costlier disease first before considering an egg drop diagnosis, Davison said.
“The birds look perfectly happy, no postmortem lesions, but they are not laying eggs, and they are laying eggs with soft shells or shell-less eggs,” she said.
Birds from at least eight Pennsylvania flocks have been infected.
Davison suspected the initial outbreak came from out-of-state eggs brought to a Pennsylvania farm for processing. Then came some local spread and outbreaks connected to a second egg processing company.
Egg production may drop dramatically, but in one flock, it only fell 8%. The history of shell quality problems helped identify the problem on that farm, Davison said.
The disease can recur even after cleaning and disinfection, but imported vaccines work well at preventing the disease.
In unvaccinated flocks, molting is a good option.
“It calms the whole reproductive system down. And after you do that molt and you bring the birds back in, the birds pretty much are normal at that point,” Davison said.
