A discovery of plague has prompted campgrounds at Angeles National Forest in Los Angeles County to be closed down as officials investigate.
A squirrel captured in a trap on July 16 tested positive for the bubonic plague, CBS Los Angeles reported.
Twisted Arrow, Broken Blade and Pima Loops of the Table Mountain campgrounds have been closed since 1:00 p.m. Wednesday, according to the Los Angeles Times.
No people have been infected.
"It is important for the public to know that there have only been four cases of human plague in Los Angeles County residents since 1984, none of which were fatal," Los Angeles County Department of Public Health chief, Dr. Jonathan Fielding, said in a statement to Reuters.
The sites will be closed for seven days while squirrel burrows in the area will be dusted for fleas.
The last time an infected animal was found was in 2010, CBS LA reported.
About five to fifteen cases of plague in humans occur each year in the western United States, the Centers for Disease Control and Prevention (CDC) reports.
Plague, or the "black death," killed an estimated one-third of Europeans during the 14th century. It is caused by the bacterium Yersinia pestis, which are found mostly in rats and fleas that feed off of them. The disease can spread to people through bites from infected fleas or rodents.
There are three forms of the disease: the bubonic plague, septicemic plague and pneumonic plague. Bubonic plague is characterized by inflammation of the tonsils, adenoids, spleen and thymus, causing symptoms like fever, aches, chills and swollen, tender lymph glands (called buboes). Septicemic plague occurs when the Yersinia bacteria multiply in the blood, potentially leading to fever, chills, internal bleeding and shock.
