A woman in Los Angeles has been taken to hospital suffering from bubonic plague, doctors have confirmed.

The woman probably caught the disease after being bitten by infected fleas in her home, said Dr Jonathan Fielding, the county’s director of public health.

Humans usually catch plague - known in medieval Europe as the Black Death - from the bites of fleas infected by dead rats. Bubonic plague is not itself contagious, but if left untreated it can morph into pneumonic plague, which can be spread from person to person.

The patient, who has not been named, was admitted to hospital on April 13 suffering from the characteristic swollen lymph nodes (buboes), fever and other symptoms. The plague diagnosis was confirmed by a blood test.

She was treated with antibiotics and is in stable condition, officials said. The woman’s family was also placed on antibiotics as a precaution, but there is no evidence they were infected. It is the first confirmed human case in Los Angeles County in more than two decades.

Health officials went to the woman’s home yesterday to trap squirrels and other wild animals. Blood samples from the animals will be sent to a lab to determine if any are infected.

Bubonic plague killed an estimated 25 million people in Europe between 1346 and 1351. The disease still exists in wild animal populations across southern and central Russia; in central Asia and parts of China; in southern Asia, Southern and East Africa; in Brazil and the Andes mountains; and also across many parts of North America from British Columbia to Mexico.

Globally, the World Health Organisation reports 1,000 to 3,000 human cases of plague every year, with an average of 1,670 per year between 1966 and 1993.The last modern outbreak in the US occurred in Los Angeles in 1924-25, when at least 30 people died.

An estimated 10 to 20 Americans contract plague each year, and about one in seven cases is fatal, according to federal statistics. The current case is unusual because it happened in a city, said Dr Fielding. Most bubonic plague outbreaks happen in the countryside.

"There’s no cause for alarm in the community," he added, stressing that the disease is not easily transmissible.

The last human cases of plague in Los Angeles County occurred in 1984 when three people contracted the disease. Two of those cases were travel-related and the third involved a person exposed to a sick animal. All three survived.

Last September, ABC News reported that three mice infected with the plague bacteria had disappeared from a laboratory. The mice were unaccounted for at the Public Health Research Institute, which is on the campus of the University of Medicine and Dentistry of New Jersey, which conducts research for the US Government on combating bio-terrorism.

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