Three ground squirrels trapped near Palomar Mountain in San Diego's North County tested positive for plague, county officials said Wednesday.
The squirrels likely were not exposed to the bacterial disease any time recently, but the existence still poses a risk to campers and hikers in the area, according to the San Diego County Department of Environmental Health.
The squirrels were trapped at the Cedar Grove Campground and the Doane Campground.
In May, another squirrel trapped at the Cedar Grove Campground also tested positive for plague. A Vector Control spokesperson said it was caught during a separate trapping, and it is not known if the same squirrel was trapped this time around.
Plague is typically found in rodents and infects humans through the bite of an infected flea. The department has not received any reported cases in humans.
It is typical for animals to test positive for plague, especially during the summer, said the department's director Jack Miller.
Still, park officials have set up signs in rural camping and hiking areas, and visitors should take precaution while in the area.
“Set up your tents away from squirrel burrows, do not feed the squirrels and warn your children not to play with squirrels,” Miller said.
Miller also said to avoid resting or camping near animal burrows in the ground and to keep pets on a leash or leave pets at home.
Symptoms of plague include swollen lymph nodes, chills and a sudden onset of fever.
For more information about plague surveillance, call the Vector Control Program at (858) 694-2888 or visit their website.