Scientists have developed nose drops that may help to stop a new epidemic of bubonic plague.

Experts fear the bacterium that causes bubonic plague is becoming resistant to antibiotics, and that the disease could re-establish itself across the world.

But a team from the University of Birmingham has developed a new vaccine that can protect mice from the disease. They told New Scientist magazine that they believe a nasal spray based on the vaccine could also protect humans.

Dr Oya Alpar and colleagues used proteins from the bacterium that causes bubonic plague to create the vaccine.

Indian victims of pneumonic plague

Bubonic plague, the disease that wiped out a third of Europe's population in the 14th century, is caused by a bacterium called Yersinia pestis which is spread by fleas on rodents.

Up to 2,000 cases of the disease are still reported worldwide every year.

The bacteria can also be spread when sick people cough up infected droplets in what is known as pneumonic plague - an even more deadly variant of bubonic plague.

Antibiotic resistance

Over use of antibiotics has increased the threat of bubonic plague

The disease can be treated with antibiotics but they must be given within 18 hours of infection.

Last year, doctors in Madagascar reported plague bacteria carrying five antibiotic resistant genes, raising the possible of a drug-resistant strain.

Dr Alpar said: "We think this is a promising approach for a whole range of diseases. We are looking at similar vaccines for tetanus and diphtheria."

The only vaccine currently licensed for plague, which consists of killed bacteria, is only effective for half its recipients.

Clinical trials of an injectable vaccine that may be more effective will start next year.

But Rick Titball, of Britain's Defence Evaluation Research Agency in Porton Down, Whiltshire, said injectable vaccines could not be administered to large populations quickly enough.

The advantage of the Birmingham vaccine is that it can be administered easily.

In September, the government published new guidelines on the prescribing of antibiotics amid fears that overprescription is leading to the rise of drug-resistant diseases.

GPs were told they should not prescribe antibiotics for conditions caused by viruses, such as coughs and colds.