A flea taken from a chipmunk at a campground near the shores of California's south Lake Tahoe area has tested positive for Bubonic plague, according to US Forest Service officials.

The Fallen Leaf camp site is still open, but all campers checking in will now be provided with educational materials about the plague. The area has also been covered with warning signs telling people not to feed or touch animals, to give dead animals a wide berth and to not bring pets into the area, reports the Reno-Gazette-Journal.

Pet cats, officials warn, are "highly susceptible to plague and can pose a direct threat to humans." The warning also advises to: "Keep cats away from rodents. Consult a veterinarian if your cat becomes sick after being in contact with rodents."

Signs warn hikers to wear long pants tucked into boot tops and to spray insect repellent containing DEET on socks and pant cuffs to reduce exposure to fleas.

Plague is naturally present in many wild areas of California, including higher elevations in El Dorado County, which includes part of the area around Lake Tahoe. However, officials become concerned when the plague is found in areas frequented by people.

The California Department of Health regularly monitors rodent populations for any sign of bubonic plague. The plague carrying flea was discovered through routine testing of rodents trapped in the area.

Plague is an infectious disease caused by the Yersinia pestis bacteria and is spread by squirrels, chipmunks and other wild rodents and their fleas. People can get plague when they are bitten by an infected flea, or by coming into close contact with an infected rodent or pet. It's most common in south western sections of the US, including Arizona, Colorado, and New Mexico, according to the Centers for Disease Control.

Symptoms of plague include fever, nausea, weakness and swollen lymph nodes, However, plague can be effectively treated with antibiotics if detected early.

Three rodents tested positive for plague in 2013 in the Lake Tahoe area, including that found on a squirrel in 2014 and cases of transmission to humans. State and local health officials will continue to monitor plague-prone areas. Officials have asked the public to report any dead or sick animals.