The Los Angeles County Health Department said the Table Mountain campgrounds of Twisted Arrow, Broken Blade and Pima Loops would be closed for at least a week, the Los Angeles Times reported Thursday.
The areas are being closed as a precaution because plague can be transmitted to humans through flea bites, the health advisory said.
The burrows of squirrels, which are known to carry the plague, will be dusted for fleas, officials said.
Jonathan E. Fielding, head of the health department, said only four cases of human plague had been reported in Los Angeles County since 1984, and none was fatal.
Fielding also advised visitors who go near the campsites not to feed wild animals and to prevent their pets from getting fleas.
Symptoms of bubonic plaque, which is caused by plague spread through flea bites, include enlargement of lymph glands and rapid onset of fever and chills.
Plague can be treated with antibiotics but can be fatal if left untreated.