Black Death genetic code 'built'

The ancient burial site is under what is now the Royal Mint

The genetic code of the germ that caused the Black Death has been reconstructed by scientists for the first time.

The researchers extracted DNA fragments of the ancient bacterium from the teeth of medieval corpses found in London.
They say the pathogen is the ancestor of all modern plagues.
The research, published in the journal Nature, suggests the 14th Century outbreak was also the first plague pandemic in history.
Humans have rarely encountered an enemy as devastating as the bacterium, Yersinia pestis. Between 1347 and 1351 it sparked the Black Death, an infection carried by fleas that spread rapidly across Europe killing around 50 million people.
Now scientists have uncovered some of the genetic secrets of the plague, thanks to DNA fragments drilled from the teeth of victims buried in a graveyard in London's East Smithfield.
Professor Johannes Krause from the University of Tubingen, Germany, was a member of the research team. He said all current strains circulating in the world are directly related to the medieval bacterium.

The plague

• The plague is one of the oldest identifiable diseases known to man
• Plague is spread from one rodent to another by fleas, and to humans either by the bite of infected fleas or when handling infected hosts
• Recent outbreaks have shown that plague may reappear in areas that have long been free of the disease
• Plague can be treated with antibiotics such as streptomycin and tetracycline
• Source: World Health Organization

"It turns out that this ancient Yersinia pestis strain is very close to the common ancestor of all modern strains that can infect humans," he said.

"It's the grandmother of all plague that's around today."
Previously researchers had assumed the Black Death was another in a long line of plague outbreaks dating back to ancient Greece and Rome.
The Justinian Plague that broke out in the 6th Century was estimated to have killed 100 million people. But the new research indicates that plagues like the Justinian weren't caused by the same agent as the medieval epidemic.
"It suggests they were either caused by a Yersinia pestis strain that is completely extinct and it didn't leave any descendants which are still around today or it was caused by a different pathogen that we have no information about yet," said Professor Krause.
Tooth power
Globally the infection still kills 2,000 people a year. But it presents much less of a threat now than in the 14th Century.

DNA fragments were extracted from teeth

According to another member of the research team, Dr Hendrik Poinar, a combination of factors enhanced the virulence of the medieval outbreak.
"We are looking at many different factors that affected this pandemic, the virulence of the pathogen, co-circulating pathogens, and the climate which we know was beginning to dip - it got very cold very wet very quickly - this constellation resulted in the ultimate Black Death."
Rebuilding the genetic code of the bacterium from DNA fragments was not easy, say the scientists.
They removed teeth from skeletons found in an ancient graveyard in London located under what is now the Royal Mint.
Dr Kirsten Bos from McMaster University explained how the process worked.
"If you actually crack open an ancient tooth you see this dark black powdery material and that's very likely to be dried up blood and other biological tissues.
"So what I did was I opened the tooth and opened the pulp chamber and with a drill bit made one pass through and I took out only about 30 milligrams of material, a very very small amount and that's the material I used to do the DNA work."
From the dental pulp the researchers were able to purify and enrich the pathogen's DNA, and exclude material from human and fungal sources.
The researchers believe the techniques they have developed in this work can be used to study the genomes of many other ancient pathogens.

bubonic plague

Rats spark Bangladesh plague fear

By Mark Dummett BBC News, Dhaka

Bubonic plague is no longer fatal if treated promptly with antibiotics

Scientists have warned of the possibility of an outbreak of bubonic plague in south-east Bangladesh because of the growing population of rats.

The rat population has soared in the past year as they feed off the region's bamboo forests, which are blossoming for the first time in decades.
Neighbouring regions in India and Burma have suffered from the same problem.
Bubonic plague, carried by rats, killed millions of Europeans during the Black Death of the 14th Century.
'Rat-flood'
Swarms of rats have been terrorising the Chittagong Hill Tracts since they crossed over the border from India in 2007.
They have destroyed the crops of about 130,000 tribal people living in this remote and impoverished region in the far south-east of Bangladesh.
A panel of scientists, sponsored by the United Nations Development Programme, now warns that what is known in Bangladesh as the rat-flood could also result in an outbreak of bubonic plague, unless the rapidly growing rat population is brought under control.
Their report states that there is already an increasing incidence of disease and fever.
They also say many have complained of being bitten by rats, though the scientists say they cannot determine whether the two facts are related.
Bubonic plague is no longer a fatal disease if treated promptly with antibiotics.
The scientists say that the Bangladeshi government should step up support for health centres so they will be ready if an outbreak occurs.
The cause of the trouble is the flowering of the region's huge bamboo forests.
Rodents multiply at an alarming rate because they can breed eight times a year after eating the bamboo blossom - four times more often than normal.
According to local folklore, the flowering of the bamboo, the subsequent surge in rat numbers and the famine that follows occur every 50 years.