A squirrel infected with plague bacteria has prompted the shutdown of several campgrounds in California's Angeles National Forest.

Los Angeles County public health department officials confirmed Wednesday that a trapped ground squirrel tested positive for plague and closed four campgrounds as a precaution.

"Plague is a bacterial infection that can be transmitted to humans through the bites of infected fleas, which is why we close affected campgrounds and recreational areas as a precaution while preventive measures are taken to control the flea population," said public health officer Dr. Jonathan E. Fielding.

Fielding added that the disease poses little threat to humans now, being very rare and easily treatable, a far cry from outbreaks like the Black Death, which killed between 75 and 200 million people in Europe in the 14th century.

"It is important for the public to know that there have only been four cases of human plague in Los Angeles County residents since 1984, none of which were fatal," he said.

This marks the fifth plague-positive squirrel found in the region since 1995.

Officials said the campgrounds will remain closed for at least seven days while they dust for fleas and conduct more tests.

Canada has not had a reported case of plague since 1939.