Yes, Lake Tahoe Chipmunks Have the Plague. But Don’t Worry (Too Much).

When California officials closed parts of South Lake Tahoe this week, the news sounded alarming: A dead chipmunk had tested positive for the plague, the rare yet highly infectious bacterial disease responsible for killing millions of people in Europe during the Middle Ages.

Lake Tahoe, which is perhaps best known as an outdoor playground for celebrities and the ultrarich in gated compounds, has seen a share of calamities lately, from wildfires to earthquakes, but the plague scare was taken in stride.

“We all need to be cautious around animals that can carry it,’’ according to Lake Tahoe Basin Management Unit of the United States Forest Service, which announced the closings on Monday.

These days the pathogen associated with the Black Death is treatable with antibiotics, and it is not that unusual for it to be found among the rodents of California, including in the higher elevation mountainous areas of El Dorado County, the authorities said.

The basic advice: Keep yourself and your pets away from the chipmunks, squirrels and other wild rodents that carry fleas infected with the disease — and wait for the authorities to spray insecticide to kill the fleas.

The closings affected the Taylor Creek Visitor Center and Kiva Beach, popular picturesque spots with nature trails near Lake Tahoe, and their parking areas, which will be closed through Friday and will likely reopen this weekend. The visitor center is about three miles north from the city of South Lake Tahoe, Calif., in El Dorado County, which is east of Sacramento.

People can be exposed to plague through an infected flea bite, handling an infected rodent, or exposure to an infected pet such as a sick cat. Early symptoms can include high fever, chills, nausea, weakness and swollen lymph nodes in the neck, armpit or groin.

What prompted the closings? Someone found a dead rodent.

El Dorado Vector Control collected the carcass from the visitor center on July 18 and sent it to the California Department of Public Health for processing and plague testing, Carla Hass, a spokeswoman for El Dorado County, said in an email.

Ms. Hass said the carcass was identified as a yellow-pine chipmunk, and 10 fleas were collected from it.

On July 29, the Health Department reported that the chipmunk had tested positive for plague. The pool of fleas also tested positive.

“On the county’s recommendation, the Forest Service enacted the closures, effective through Friday,” Ms. Hass said.

No humans are believed to have come into contact with the chipmunk, said Lisa Herron, a spokeswoman for the Forest Service at Lake Tahoe.

On Thursday, the service began dusting an insecticide in rodent burrows to reduce the flea population.

Human cases of plague are rare and people can be treated with antibiotics, the forest service said. But the disease can become severe and sometimes fatal if it is not treated early, according to the state Health Department.

Last year, a South Lake Tahoe resident tested positive for plague, according to El Dorado County officials. The resident, an avid walker, may have been infected after being bitten by a flea. The case was the first in five years in California, according to the Tahoe Daily Tribune.

It might seem like Lake Tahoe can’t catch a break lately. It has been struck with drought, wildfires and earthquakes. This summer, officials implemented “enhanced fire restrictions” that prohibited wood and charcoal fires in the Tahoe basin and campgrounds. Last month, a wildfire that had been burning for two weeks just south of Lake Tahoe prompted a wave of evacuations and event cancellations.

But when it came to a deadly medieval disease the official advice was focused on basic precautions, mainly involving pets.

Ms. Herron said that people who visit areas where active plague has been found should stay on trails and keep their pets away from rodents.

She added, “If you must bring your pet, keep them on short leash and do not let them investigate rodent burrows.”