Riverside County officials are advising that for the first time in almost a decade, a ground squirrel in the San Jacinto Mountains has tested positive for exposure to fleas infected with bacteria that can cause plague.
Norma Arceo with the California Department of Public Health said her agency confirmed results from the Riverside County Department of Environmental Health that the rodent was positive for the bacteria Yersinia pestis.
The squirrel was collected Sept. 6 at the Fern Basin campground during routine testing by the county. The campground is north of Idyllwild.
“Historically, positive test results have occurred routinely among ground squirrels in the mountain region. Despite positive tests in other California counties and regular, routine testing locally, Riverside County has had no positive tests for almost a decade. Further tests on animals in the area will be conducted this month,” Ray Smith, public information officer for Riverside County, advised in a news release today.
According to the Centers for Disease Control, there are three forms of plague -- Bubonic, Septicemic and Pneumonic -- but they all derive from the same Y. pestis bacteria that can be transmitted from wild rodents to humans through bites from infected fleas, or by inhaling infected respiratory droplets in the case of pneumonic plague, which is transferable from human to human.
Although there are no vaccines currently available to protect against plague, the CDC states the overall mortality rate in the United States is down to approximately 11 percent due to advances in antibiotic treatment for humans infected with the bacteria.
“Plague can still be fatal despite effective antibiotics, though it is lower for bubonic plague cases than for septicemic or pneumonic plague cases,” the CDC states on its website.
History books have chronicled the history of plague, including the "Black Death" or “Great Plague” pandemic that wiped out an estimated 60 percent of the European population during the 14th Century.
County health officials said the risk of plague transmission to humans is minimal today if people take proper precautions. U.S. Forest Service officials and the campground host where the rodent was found were notified about the test results so that campers can be educated about taking proper precautions, Smith said, noting that county officials ensured that warning signs are clearly posted and recommend that visitors, hikers and campers follow the precautions to prevent contact with fleas, including:
- Avoid contact with ground squirrels, tree squirrels and other wild animals.
- Do not feed or touch wild animals, or touch dead animals.
- Do not rest or camp near animal burrows.
- Protect your pets by leaving them at home, or by keeping them on a leash and using flea-control methods.
- Contact your doctor immediately if you become ill after visiting a known plague area. Symptoms include a sudden onset of fever, chills and tender swollen lymph nodes.