Two more chipmunks have tested positive for plague at the South Shore, but the risk of the bacterial disease spreading remains low, according to El Dorado County health officials.
Thirty-eight chipmunks and three squirrels were tested for the disease after a chipmunk near Taylor Creek Visitor Center was found with plague earlier this month, said Karen Bender, a senior environmental health specialist with the county.
The results of the testing show a "really low risk" of infection, especially with the recent appearance of snow at the South Shore, Bender said.
"Risk of transmission is significantly reduced during the winter months because rodents and their fleas are less active when the weather is cold," said interim El Dorado County Health Officer Robert Hartmann in a Friday statement.
One of the chipmunks tested since the initial discovery was found in the Tallac Historic Site area and one was near Taylor Creek Visitor Center, according to the statement.
The results are not unexpected, but do warrant precautions, Hartmann said. Warning signs will remain in areas where infected rodents were found and at surrounding campgrounds. Additional rodent testing is expected in the spring.
Lower recreational activity at U.S. Forest Service sites also reduces people's risk of contracting the disease, agency spokeswoman Cheva Heck said. She said the results of the additional testing were positive.
"From our point of view it really is encouraging and we're looking forward to working with the health department next spring," Heck said.
Plague is naturally present in California, most commonly in the mountains and foothills. Although cases of human plague are rare, people can become infected through contact with infected animals or fleas. Symptoms of plague typically arise within two weeks of exposure and include fever, nausea, weakness and swollen lymph nodes. The disease can be treated with antibiotics if detected early.