Sections of the National Wildlife Refuge in Rocky Arsenal Mountain were closed at the end of July as a precautionary measure after the disease was discovered, the U.S. Fish and Animal Service reported.
The unaffected asylum areas reopen on Saturday, but other venues in the Commerce City, a suburb north of Denver, will remain closed until Labor Day weekend, the Tri-County Department of Health announced.
"Prairie dog colonies are being monitored and furrows treated with insecticide, but flea data are still available in tourism and camping areas that could endanger humans and pets so that these areas will remain closed," said John M. Douglas, Jr., executive director of the Tri-County Department of Health.
There are no reports of human infections, he said.