More cases were linked to a seventh commercial farm described only as a "duck meat bird facility" in Lancaster County, with the outbreak having been reported late last month, the USDA said.
More than 19,300 birds at the facility were depopulated, according to a chart on the USDA website.
Most of the cases in Pennsylvania were reported in flocks of commercial table egg layers, totaling about 3,450,100, according to USDA data.
Thirty-two states have been affected by the outbreak so far, the USDA said.
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