Table Mountain campground in the San Gabriel Mountains has been closed indefinitely after two squirrels were found dead there from plague.
The 117-site campground, north of Big Pines near the San Bernardino County line, has been dusted twice this week with a pesticide, said Frank Hall, senior biologist with the Los Angeles County Department of Health Services' Vector Control Program.
"Some people were very upset that we closed it last weekend," Hall said. "But we had no choice. We want to protect the general public."
The bacterial infection, known as bubonic plague in humans and as sylvatic plague in animals, is endemic to the San Gabriel Mountains and never can be eradicated, Hall said.
"It pops up every so often," he said, adding that each case represents a separate incident and not a continuation of one outbreak. "Our problem is to try to catch it before it enters an infectious stage."
The disease can be transmitted through the bite of an infected flea.
Plague symptoms in humans include enlargement of lymph glands near the flea-bite area, followed by the rapid onset of fever and chills. If untreated, bubonic plague often progresses to septicemia and plague pneumonia, which can be fatal.
Three cases of plague were discovered in Los Angeles County last year. Two were bubonic and one resulted in plague pneumonia, but none was.
Hall said that a flea-count to be taken today would determine whether the campground will be opened for Labor Day weekend.
The acceptable number of fleas under state standards is 0.3 per animal, Hall said. Animals examined last week had as many as 16 fleas.
The deaths of ground squirrels collected at Chantry Flat and at the U.S. Forest Service information booth, north of Azusa, two weeks ago also have been attributed to sylvatic plague.
In addition, four coyotes in the Santa Anita flood debris basin have been found dead from plague.
Hall said that signs have been posted warning campers that sylvatic plague has been identified in those areas.