The Grand Canyon temporarily closed a popular cave because of concerns about the hantavirus.
Park officials announced Wednesday that the Cave of the Domes will be sealed off until further notice.
They said rodent activity has created a risk of people contracting the virus.
Hantavirus pulmonary syndrome is a rare but serious disease that can spread through contact with the urine, saliva, blood or droppings of infected rodents.
Infection occurs when someone breathes in virus particles.
According to the National Park Service, there have been five cases in Coconino County since 2006, including two this year.
Health officials said people camping or doing other outside activities should not sleep near rodent nests or burrows.
The Cave of the Domes is the only cave inside the park open to the public without a permit.