Alveolar hydatid disease in Minnesota. First human case acquired in the contiguous United States.

A 56-year-old woman from southwestern Minnesota underwent an extended left hepatic lobectomy to remove a large multinodular mass with a necrotic central cavity. The clinical, serological, and pathological findings led to the diagnosis of alveolar hydatid disease, and specific identification of Echinococcus multilocularis was achieved by growing mature larvas in voles inoculated intraperitoneally with tissue from the hepatic lesions. The patient probably acquired her infection some years previously from pet cats or dogs that had become infected by ingesting infected rodents. In North America E multilocularis is enzootic in the northern tundra zone of Alaska and Canada. Since 1964 the cestode has been recognized with increasing frequency in several north-central states, including Minnesota. The parasite may extend its range farther south, since suitable animal hosts occur throughout the United States.