Which region is endemic for plague in the United States according to the material?

• A. Eastern U.S.
• B. Western U.S.
• C. Australia, Northern Europe, and Mexico
• D. Both B And C

Answer: (B)

Plague is maintained in specific geographic foci, with rodent–flea cycles keeping the bacteria circulating in nature. In the United States, those endemic foci are in the western states, where rodents like prairie dogs and related species serve as reservoirs and fleas such as Oropsylla montana transmit it. This geographic pattern explains why human cases and sustained enzootic activity occur primarily in the western U.S.; the eastern states do not have established endemic foci. The other options point to regions outside the United States or mix regions in a way that doesn’t fit the material, so the western United States is the correct endemic region.