RIVERSIDE - A ground squirrel netted at a campground in the San Jacinto Mountains tested positive for bubonic plague bacteria, prompting Riverside County health officials today to warn campers to take precautions.

"We don't want to incite panic. We just want everybody to be educated," said county Department of Environmental Health spokeswoman Dottie Merki.

Merki said the squirrel was caught on Sept. 6 during routine trapping at the Fern Basin campground.

Rodents are trapped in the mountain location seasonally to ascertain whether they're carrying diseases, according to Merki.

She said it's the first time in nearly a decade that a squirrel has tested positive for plague exposure.

"It wasn't showing any plague symptoms," Merki said. "But the blood sample we took showed it had been exposed."

Fleas that feed on infected rats and other rodents carry plague bacteria and can transfer it to humans, causing a bacterial infection in some cases. People can also be infected by handling an animal that died of Advertisement

[ Berry-Bell and Hall Mortuary ] plague, according to the National Institutes of Health.

There are different varieties of plague -- bubonic, pneumonic and septicemic. Bubonic is the deadliest, killing about half of all victims if left untreated, according to the NIH.

Merki said plague is endemic to a number of mountain locations throughout California, including the San Jacinto wilderness.

The Fern Basin campground, perched above 6,000 feet near Idyllwild, is operated by the San Bernardino National Forest.

Merki said a few simple precautions can minimize the possibility of campers and hikers being exposed to plague-infected fleas and rodents.

"Use a good flea repellent when you're out there," she said. "Keep your campsite away from burrows and stay away from squirrels, chipmunks and all wild animals really. It's better to leave pets at home."

Plague symptoms include sudden fever, chills and tender or swollen lymph nodes.

More information is available at the county Department of Environmental Health website, http://www.rivcoeh.org/opencms/index.html, or the state's site, http://www.cdph.ca.gov/programs/cid/Pages/default.aspx.