Parts of a national forest in California have been evacuated and closed down after a squirrel was found to be infected with the plague.

Los Angeles officials say visitors were ordered to leave the Angeles National Forest as a precaution after the rodent was trapped in a routine check.

They said no people in the area were believed to have been infected with the disease, known as the Black Death.

The plague killed as many as 25 million Europeans during the Middle Ages.

Analysis It sounds like a screenplay for a Hollywood B-movie: bubonic plague-infected squirrels descend on Los Angeles. But despite the excitement among Angelenos on social media about the "Black Death" being found at a California campsite, health officials say this is not a problem for urban squirrels. City conditions do not lend themselves to having fleas co-existing in large numbers as they would in a forested area, they say. Even in this forest area where the squirrel was found on Thursday, only five "plague-positive" squirrels have turned up in the last 20 years or so. This particular squirrel is dead - tests are being conducted to determine if it died of natural causes or the plague itself.

It is a bacterial infection which can be transmitted to humans through the bites of infected fleas.

If not treated with antibiotics, it is usually deadly.

There have been only four cases of human plague in Los Angeles County since 1984, none of which was fatal, according to officials.

Further testing of squirrels in the region will be carried out before the campgrounds are re-opened to the public.

Jonathan Fielding, director of the Los Angeles County Department of Public Health, told the BBC that agriculture workers would dust squirrel burrows in order to reduce the flea population.

He said that while the area was closed to camping, people would still be able to hike through.

He advised that anyone who wished to do so should use insect repellent and ensure that any pets they bring have a flea collar.