Cestode in North Dakota: echinococcus in field mice.

Field mice (Microtus pennsylvanicus and Peromyscus maniculatus) are naturally infected with Echinococcus multilocularis. Thus, the sylvatic cycle (fox to field mice to fox) has been established in North Dakota. This cestode is expected to extend its range to other agricultural regions of the continental United States where similar conditions favorable for the completion of its life cycle exist.