A squirrel found dead at Lake Tahoe last month has tested positive for the plague, health officials said, marking the latest incidence of the disease in California that forced the temporary closure of two Yosemite National Park campgrounds.
The Lake Tahoe squirrel was discovered at a picnic area near the Tallac Historic Site on Aug. 17 and sent to a state laboratory for testing, the El Dorado County Environmental Management Division, said in a written statement released on Friday.
Test results confirmed last Wednesday that the rodent had plague, El Dorado health officials said, and warning signs were posted for visitors to the area.
The officials said they were not aware of any contact between humans and the squirrel.
"Plague is naturally present in many parts of California, including higher elevation areas of El Dorado County, so we need to be cautious around animals that can carry it," Karen Bender, a supervisor with the El Dorado County Environmental Management Division, said in a written statement.
In August, health officials closed two Yosemite National Park campgrounds for to be treated with insecticide after a child who camped there was hospitalized with the centuries-old scourge.
That case marked the first time a human was known to be infected with plague, which is carried by rodents and the fleas that live on them, in California since 2006.
A second Yosemite visitor, who had traveled there from Georgia, was later diagnosed with the disease.
Officials have since urged visitors to Yosemite, which is about 120 miles from Lake Tahoe, to avoid walking or camping near rodent burrows, to wear long pants tucked into boots when hiking and to spray insect repellent containing the chemical diethyltoluamide, or DEET, on socks and pant legs to reduce the risk of flea bites
Last year in El Dorado County, two live rodents tested positive for plague antibodies, and in 2013 three tested positive, according to health officials there. There were no reports of illness to people.
An elderly Utah resident died from plague in August and two people have succumbed to the disease this year in Colorado.
The U.S. Centers for Disease Control says the plague was introduced to the United States in 1900 by rat–infested steamships that had sailed from affected areas, mostly in Asia.
Early symptoms of plague include high fever, chills, nausea, weakness and swollen lymph nodes in the neck, armpit or groin.
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