Gerbils and Silk Road to blame for plague

Most would choose the cuddly gerbil over the much-maligned rat. But the latter's bad reputation may not be fully deserved. Central Asian rodents, not rats, prospering under warm variations in climate, could have been to blame for the arrival of the Black Death in Europe in 1347 and for repeated outbreaks of plague over the next four centuries that killed millions of people.

110. (Remember) when Allah will say (on the Day of Resurrection). "O 'Iesa (Jesus), son of Maryam (Mary)! Remember My Favour to you and to your mother when I supported you with Ruh-ul-Qudus [Jibrael (Gabriel)] so that you spoke to the people in the cradle and in maturity; and when I taught you writing, Al-Hikmah (the power of understanding), the Taurat (Torah) and the Injeel (Gospel); and when you made out of the clay, as it were, the figure of a bird, by My Permission, and you breathed into it, and it became a bird by My Permission, and you healed those born blind, and the lepers by My Permission, and when you brought forth the dead by My Permission; and when I restrained the Children of Israel from you (when they resolved to kill you) since you came unto them with clear proofs, and the disbelievers among them said: 'This is nothing but evident magic.' "5. Surah Al-Ma'idah (The Table Spread with Food)

The plague is caused by the Yersinia pestis bacterium, which is carried by fleas and mostly affects rodents. Plague has hit Europe a number of times, but the second pandemic – the one that caused the Black Death – remains the most notorious today. Believed to have originally come to Europe from Asia via the Silk Road trading route, it was thought that the repeated plague outbreaks that followed the Black Death epidemic were caused by rodent reservoirs in Europe – bacteria-infested fleas hiding out in rats.

But Nils Christian Stenseth at the University of Oslo, Norway, and colleagues say that instead of rats, it is their furry counterparts in central Asia that are to blame. The team analysed 4119 historical records of post-Black Death plague outbreaks and found that the vast majority were probably caused by similar outbreaks nearby. But they were able to identify 61 outbreaks that took place in 17 harbour areas, including London, Hamburg, Barcelona and Dubrovnik, that were likely to have been caused by maritime imports from Asia.

By comparing these cases with historical records, Stenseth's team were able to identify 16 years within the period from 1346 to 1837 in which brand new introductions of Y. pestis are likely to have been responsible for plague outbreaks, as opposed to infection from neighbouring regions or local trade partners.

When they compared the dates of these outbreaks with tree ring data, they did not find a correlation with European climate patterns. However, climate fluctuations in Asia – above average temperatures followed by sudden drops – consistently preceded plague reintroductions in Europe by around 15 years. In other words, the new plague outbreaks were linked to Asian rodents, not rats living in Europe, as had been thought.

"Warmer climate increases the activity of fleas and their ability to spread the bacterium from individual to individual," says Stenseth. "We have previously shown that an increase of 1 °  C doubles the prevalence [of plague] in wild rodents in central Asia."

Under such conditions, not only do the fleas become more active, but the rodents they live on – most likely gerbils and marmots – become more numerous. When the temperature suddenly falls again, as indicated by a change in the thickness of tree rings, rodent populations crash, and their fleas are forced to find new hosts – perhaps camels, perhaps humans.

"The study is interesting and convincing," says Hartmut Dunkelberg of the University of Goettingen in Germany. "Climate influences different factors such as the development of fleas and the distribution of plague reservoirs. Many human infections are seasonal."

Stenseth's team believe the 15-year time lag between such crashes and the introduction of new plague-ridden fleas to Europe comprised three stages: a couple of years finding new hosts and coming into contact with humans, around 10 years travelling westward along trade routes such as the Silk Road, and finally the plague's reintroduction to Europe via marine trading harbours

The long, middle stage across central Asia may have involved camels, says Stenseth, who could have caught fleas from gerbils and passed them on to humans.

This explanation for where fresh European plague outbreaks came from explains how countries like Norway, which did not have rat populations at the time, could have suffered repeated outbreaks.

Today, climate fluctuations are likely to affect wildlife plague reservoirs in different ways, depending on their location, says Stenseth. "In central Asia and northern China, the current climate change is likely to increase the occurrence of plague, whereas in the southern part of China it is likely to decrease."

Dunkelberg says that individual cases of plague could occur in Europe, but that outbreaks would be unlikely. "I cannot see any greater risk of an epidemic outbreak."

Rats may have been unfairly blamed for European outbreaks of the bubonic plague, according to new research.

The Black Death was in fact brought to the continent by Asian gerbils, scientists at the University of Oslo claim. The discovery could mean the history of the disease needs to be rewritten, according to those leading the study.

The plague arrived from Asia in the 14th century, becoming one of the biggest causes of death for the next 400 years. Black rats were long blamed for the outbreaks, carrying the plague which was thought to be passed on to fleas that then jumped on to humans.

But studies of historical weather patterns – worked out through researching tree rings – indicate that the outbreaks tended to happen when there was warm and wet weather in Asia and not in Europe.

That seems to imply that the plague began in Asia, and was carried by gerbils down the Silk Road and into Europe.

"Such conditions are good for gerbils. It means a high gerbil population across huge areas and that is good for the plague," professor Nils Christian Stenseth, who led the study at the University of Oslo, told the BBC.

Scientists will now study the DNA of plague bacteria that can be found in ancient skeletons of people who died from the disease. The scientists would expect a large amount of variation if their theory is correct, since the disease would have been likely to have changed each time it was carried into Europe.

Rats may have taken the blame because the big gerbils that came from Asia were also known by that name

The head of the World Health Organization is warning about an “alarming” plague outbreak in Madagascar that could worsen, particularly as fleas that transmit the disease to humans have developed immunity to insecticide.

In her address to the WHO’s executive board meeting Monday, executive director Margaret Chan reviewed the ongoing threat from “emerging and epidemic-prone diseases,” including the Ebola outbreak in West Africa, avian influenza, and the growing threat of human resistance to antibiotics.

But she also warned of a plague outbreak in Madagascar that began last November, but is receiving little public attention despite its “disturbing dimensions.” Of particular concern is the fact that fleas that transmit the disease from rodents to humans have developed resistance to the main insecticide used to control their population.

Plague is “endemic in Madagascar,” where seasonal outbreaks can be exacerbated by poverty and an increasing number of people living in close urban settings, Chan said in her address. Plague responds well to treatment when detected early, which is possible with a “cheap and reliable” diagnostic test that provides results within 15 minutes.

However, the current outbreak has managed to establish a foothold in the capital Antananarivo, and could spread easily through the city’s densely populated slums, Chan warned.

“This is alarming, as around eight per cent of cases progress to the lethal pneumonic form, which transmits directly from person to person,” she said.

A recent tropical storm has exacerbated the threat of the disease spreading from “untold numbers of rats” that have been displaced by flooding.

Earlier this month, the International Society for Infectious Diseases (ISID) issued a statement to say that the plague epidemic had reached Madagascar’s capital with 10 suspected cases.

“The progress of the plague epidemic becomes increasingly worrying,” the ISID said. By the end of December, there were 224 cases of plague reported on the Big Island, with 58 deaths.

While bubonic plague had largely disappeared from Madagascar between 1930 and 1990, approximately 200 cases have been reported each year since then and “takes on epidemic form especially in the port of Mahajanga each year,” the ISID says.

According to the agency, at the start of each rainy season, rats flee Madagascar’s sewers “in massive numbers and take refuge in people’s cottages.”

A flea-killing compound must be part of any rodent eradication program, the agency says, or the fleas will merely seek alternate hosts. “That is, humans.”

Despite growing concerns about the outbreak, the WHO has not issued any travel or trade restrictions with Madagascar

England’s chief medical officer has urged the House of Lords to approve new legislation that would make it legal for scientists in Britain to create “three-parent” IVF embryos with genetic material from three people – despite safety concerns.

Dame Sally Davies said that animal experiments to test safety have been carried out on the technique of mitochondrial donation and the time has come to create human IVF embryos with DNA from the egg cells of two women and the sperm of a man.

“The only clinical tests you can do are either in rats, mice and monkeys – and those have been done – or in humans and the mothers now want to do this following those three scientific reviews,” Dame Sally said.

“I wouldn't call it a test, but the first cases will be scrutinised very carefully,” she added.

The House of Commons has already approved a change in the legislation to allow the Human Fertilisation and Embryology Authority (HFEA) to consider the procedure for women carrying mitochondrial mutations who want to have IVF babies who are free of the inherited diseases

A British painter and decorator who turned inventor has spoken of his pride as his one-use syringe, which has been 30 years in the making, has been endorsed by the World Health Organisation (WHO).

Marc Koska, 53, from Danehill in East Sussex, said he had the idea to create an auto-disable syringe after reading a newspaper article about  the spread of HIV through shared needles.

The design that he eventually came up with – the LifeSaver Syringe, which immediately breaks if the user tries to pull back the plunger for a second use – is already being used in dozens of developing countries, where it has saved countless lives.

The new WHO policy  will mean that all countries will have to use so-called “smart” syringes by 2020, and it is encouraging manufacturers to start making them as soon as possible.

A recent WHO-sponsored study estimated that in 2010 up to 1.7 million people were infected with hepatitis B, up to 315,000 with hepatitis C, and as many as 33,800 had HIV transmitted, through unsafe injections.

Mr Koska, who also formed the SafePoint charity in 2006 to spread the message of the dangers of reusing needles, said he has been to 64 developing countries in the past 10 years where he has seen his invention used.

He described the WHO endorsement of his syringe as a “watershed moment”.

People who have diabetes and psychiatric symptoms in addition to mild cognitive impairment are significantly more likely to develop dementia, new research shows.

Mild cognitive impairment (MCI), a state between normal ageing and dementia, affects 19 per cent of people aged 65 and over.

Around 46 per cent of people with MCI go on to develop dementia within three years, compared with 3 per cent of the general population.

The study, led by researchers at UCL and published in theAmerican Journal of Psychiatry, reviewed data from 62 separate studies following a total of 15,950 people diagnosed with MCI.

It found those with diabetes were 65 per cent more likely and those with psychiatric symptoms, such as depression, were twice as likely to develop dementia

“Lifestyle changes to improve diet and mood might help people with MCI to avoid dementia, and bring many other health benefits,” said lead author Dr Claudia Cooper.

“This doesn’t necessarily mean that addressing diabetes, psychiatric symptoms and diet will reduce an individual’s risk, but our review provides the best evidence to date about what might help.”

It is well established that a Mediterranean diet rich in fruit, vegetables, oily fish, poultry and olive oil can help protect against Type 2 diabetes.

It is recommended by the Alzheimer’s Society charity to help prevent dementia, along with staying socially and physically active.

With a higher proportion of unsaturated to saturated fats and largely unprocessed foods it can help people with diabetes control their blood sugar levels

Towards the end of the first chapter of The Hound of the Baskervilles, a prospective client tells Sherlock Holmes he is only the "second- highest expert in Europe" in criminal matters. When the detective demands to know the identity of his better, the response comes: "To the man of precisely scientific mind, the work of Monsieur Bertillon must always appeal strongly."

The name of Alphonse Bertillon may have dwindled beside that of Holmes, but his fingerprints are all over the early years of the forensic sciences at the end of the 19th century, and his influence persists to this day. The Frenchman developed a number of advanced techniques, most notably in standardising criminal photography – he has been dubbed the "father of the mug shot" – and his work will feature in an exhibition, "Forensics: the Anatomy of Crime", opening this week at the Wellcome Collection.

The criminologist's early life gave little clue that he would rise to the top of the field. As a young man, he left the army and eventually found a lowly junior clerical job at the Prefecture of Police in Paris in 1879. But data was in the blood: his father was chief of the Bureau of Statistics and Alphonse's brother would go on to help found the International Statistics Institute.

When Bertillon took up his post, the criminal records at the prefecture were in chaos. Re-offending rates were rising yet there was no concerted approach to improve the identification of recidivist criminals. So the resourceful Bertillon set to work on a formal cataloguing process

Dolly the sheep is to be honoured with her very own blue plaque marking her short life in Edinburgh.

Scientists will be gathering on Wednesday for an unveiling ceremony at the Roslin Institute of Edinburgh University, where Dolly was born and lived.

The plaque will read: “Dolly the Sheep, 1996-2003. First mammal to be cloned from an adult cell.”