Pulmonary echinococcosis caused by Echinococcus canadensis G8 in a white-tailed deer (Odocoileus virginianus), Pennsylvania, USA, 2026.

Abstract

Cystic echinococcosis, caused by the two zoonotic cestodes Echinococcus granulosus and Echinococcus canadensis, is emerging in new regions of the United States and Canada. In January 2026, an adult female hunter-harvested white-tailed deer (Odocoileus virginianus) from Pennsylvania, USA exhibited pulmonary hydatid cysts. Morphologic identification of metacestodes in cystic fluid and subsequent PCR and sequencing confirmed this deer was infected with Echinococcus canadensis G8. Although E. canadensis commonly infects cervids at northern latitudes, recent infections in definitive wild canid hosts have been documented in the eastern USA. Published reports of E. canadensis in white-tailed deer, the most popular game species in the eastern USA, are rare and confirm that white-tailed deer are viable intermediate host species in the eastern USA. These findings further emphasize the presence of E. canadensis in the eastern United States, highlighting the risk that these parasites may pose to humans, domestic animals, livestock, and wildlife.