The California Department of Public Health announced it would conduct an environmental evaluation in Yosemite and neighboring areas, including the Stanislaus National Forest.

Other members of the child's camping party are being monitored, but no other campers have shown symptoms characteristic of the bacterial disease, which is normally spread through the bite of an infected flea or by coming in contact with a rodent that carries infected fleas.

“Human cases of plague are rare, with the last reported human infection in California occurring in 2006,” said Dr. Karen Smith, the Director and State Health Officer of the CDPH. “Although this is a rare disease, people should protect themselves from infection by avoiding any contact with wild rodents. Never feed squirrels, chipmunks, or other rodents in picnic or campground areas, and never touch sick or dead rodents. Protect your pets from fleas and keep them away from wild animals,” Smith added.

An adult and a teen died from the plague earlier this year in Colorado in two unrelated incidents.

The plague killed millions of people in the 1300s, but developments in modern medicine halted widespread infection of the disease.