The avian flu reached its first commercial farms in Berks County, affecting more than 29,000 ducks.
USDA, Animal and Plant Health Inspection Service confirms 29,500 birds are affected in Berks at a breeder facility, bringing the statewide death toll to 3,874,700.
The second Berks County operation impacted produces duck meat, according to a USDA site. As of Wednesday, the birds affected at the meat producer was listed at zero.
The avian flu also reached seven commercial farms in Lancaster County.
Penn State University and state officials are keeping a close eye on the spread of the virus, which is believed to be stronger than previous years.
Officials say it is rare for humans to contract it, farmers are urged to take special precautions, like wearing rubber boots or something that can be washed and special clothes. Shoes can carry the virus.
Commercial poultry farms and people who have chickens in their backyards should be on high alert.