29/03/2020
- Virus may have jumped from animal to humans long before the first detection in Wuhan, according to research by an international team of scientists
- Findings significantly reduce the possibility of the virus having a laboratory origin, director of the US National Institute of Health says
An international team of scientists say the coronavirus may have jumped from animal to humans long before the first detection in China. Photo: AP
The
coronavirus that causes Covid-19 might have been quietly spreading among humans for years or even decades before the sudden outbreak that sparked a global health crisis, according to an investigation by some of the world’s top virus hunters.
Researchers from the United States, Britain and Australia looked at piles of data released by scientists around the world for clues about the virus’ evolutionary past, and found it might have made the jump from animal to humans long before the first detection in the central China city of Wuhan.
Though there could be other possibilities, the scientists said the coronavirus carried a unique mutation that was not found in suspected animal hosts, but was likely to occur during repeated, small-cluster infections in humans.
The study, conducted by Kristian Andersen from the Scripps Research Institute in California, Andrew Rambaut from the University of Edinburgh in Scotland, Ian Lipkin from Columbia University in New York, Edward Holmes from the University of Sydney, and Robert Garry from Tulane University in New Orleans, was published in the scientific journal Nature Medicine on March 17.
Dr Francis Collins, director of the US National Institute of Health, who was not involved in the research, said the study suggested a possible scenario in which the coronavirus crossed from animals into humans before it became capable of causing disease in people.
“Then, as a result of gradual evolutionary changes over years or perhaps decades, the virus eventually gained the ability to spread from human to human and cause serious, often life-threatening disease,” he said in an article published on the institute’s website on Thursday.
In December, doctors in Wuhan began noticing a surge in the number of people suffering from a mysterious pneumonia. Tests for flu and other pathogens returned negative. An unknown strain was isolated, and a team from the Wuhan Institute of Virology led by Shi Zhengli traced its origin to a bat virus found in a mountain cave close to the China-Myanmar border.
The two viruses shared more than 96 per cent of their genes, but the bat virus could not infect humans. It lacked a spike protein to bind with receptors in human cells.
Coronaviruses with a similar spike protein were later discovered in Malayan
pangolins
by separate teams from Guangzhou and Hong Kong, which led some researchers to believe that a recombination of genomes had occurred between the bat and pangolin viruses.
Doctors in Wuhan began noticing a surge in the number of people suffering from a mysterious pneumonia in December. Photo: Handout
But the new strain, or SARS-Cov-2, had a mutation in its genes known as a polybasic cleavage site that was unseen in any coronaviruses found in bats or pangolins, according to Andersen and his colleagues.
This mutation, according to separate studies by researchers from China, France and the US, could produce a unique structure in the virus’ spike protein to interact with furin, a widely distributed enzyme in the human body. That could then trigger a fusion of the viral envelope and human cell membrane when they came into contact with one another.
Some human viruses including HIV and Ebola have the same furin-like cleavage site, which makes them contagious.
It is possible that the mutation happened naturally to the virus on animal hosts. Sars (severe acute respiratory syndrome) and Mers (Middle East respiratory syndrome), for instance, were believed to have been direct descendants of species found in masked civets and camels, which had a 99 per cent genetic similarity.
There was, however, no such direct evidence for the novel coronavirus, according to the international team. The gap between human and animal types was too large, they said, so they proposed another alternative.
“It is possible that a progenitor of SARS-CoV-2 jumped into humans, acquiring the genomic features described above through adaptation during undetected human-to-human transmission,” they said in the paper.
“Once acquired, these adaptations would enable the pandemic to take off and produce a sufficiently large cluster of cases to trigger the surveillance system that detected it.”
They said also that the most powerful computer models based on current knowledge about the coronavirus could not generate such a strange but highly efficient spike protein structure to bind with host cells.
The study had significantly reduced, if not ruled out, the possibility of a laboratory origin, Collins said.
“In fact, any bioengineer trying to design a coronavirus that threatened human health probably would never have chosen this particular conformation for a spike protein,” he said.
The findings by Western scientists echoed the mainstream opinion among Chinese researchers.
Zhong Nanshan, who advises Beijing on outbreak containment policies, had said on numerous occasions that there was growing scientific evidence to suggest the origin of the virus might not have been in China.
“The occurrence of Covid-19 in Wuhan does not mean it originated in Wuhan,” he said last week.
A doctor working in a public hospital treating Covid-19 patients in Beijing said numerous cases of mysterious pneumonia outbreaks had been reported by health professionals in several countries last year.
Re-examining the records and samples of these patients could reveal more clues about the history of this worsening pandemic, said the doctor, who asked not to be named due to the political sensitivity of the issue.
“There will be a day when the whole thing comes to light.”
Source: SCMP
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05/10/2019
Visitors tour the desert on camels at Shapotou Scenic Area in Zhongwei, northwest China’s Ningxia Hui Autonomous Region, Oct. 3, 2019. Since the start of the National Day holiday, Shapotou Scenic Area has entered its peak season for tourism. (Photo by Yang Zhisen/Xinhua)
Source: Xinhua
Posted in camels, China alert, enjoy, leisure time, National Day, National Day holiday, Ningxia Hui Autonomous Region, peak season, People, Shapotou Scenic Area, the desert, tour, Tourism, Uncategorized, visitors, Zhongwei |
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08/07/2019
- Settlements along the route linking Europe and Asia thrived by providing accommodation and services for countless traders
- Formally established during the Han dynasty, it was a 19th-century German geographer who coined the term Silk Road
The ruins of a fortified gatehouse and customs post at Yunmenguan Pass, in China’s Gansu province. Photo: Alamy
We have a German geographer, cartographer and explorer to thank for the name of the world’s most famous network of transcontinental trade routes.
Formally established during the Han dynasty, in the first and second centuries BC, it wasn’t until 1877 that Ferdinand von Richthofen coined the term Silk Road (historians increasingly favour the collective term Silk Routes).
The movement of merchandise between China and Europe had been taking place long before the Han arrived on the scene but it was they who employed troops to keep the roads safe from marauding nomads.
Commerce flourished and goods as varied as carpets and camels, glassware and gold, spices and slaves were traded; as were horses, weapons and armour.
Merchants also moved medicines but they were no match for the bubonic plague, which worked its way west along the Silk Road before devastating huge swathes of 14th century Europe.
What follows are some of the countless kingdoms, territories, (modern-day) nations and cities that grew rich on the proceeds of trade, taxes and tolls.
China
A watchtower made of rammed earth at Dunhuang, a desert outpost at the crossroads of two major Silk Road routes in China’s northwestern Gansu province. Photo: Alamy
Marco Polo worked in the Mongol capital, Khanbaliq (today’s Beijing), and was struck by the level of mercantile activity.
The Venetian gap-year pioneer wrote, “Every day more than a thousand carts loaded with silk enter the city, for a great deal of cloth of gold and silk is woven here.”
Light, easy to transport items such as paper and tea provided Silk Road traders with rich pickings, but it was China’s monopoly on the luxurious shimmering fabric that guaranteed huge profits.
So much so that sneaking silk worms out of the empire was punishable by death.
The desert outpost of Dunhuang found itself at the crossroads of two major Silk Road trade arteries, one leading west through the Pamir Mountains to Central Asia and another south to India.
Built into the Great Wall at nearby Yunmenguan are the ruins of a fortified gatehouse and customs post, which controlled the movement of Silk Road caravans.
Also near Dunhuang, the Mogao Caves contain one of the richest collections of Buddhist art treasures anywhere in the world, a legacy of the route to and from the subcontinent.
Afghanistan
Afghanistan’s mountainous terrain was an inescapable part of the Silk Road, until maritime technologies would become the area’s undoing. Photo: Shutterstock
For merchants and middlemen hauling goods through Central Asia, there was no way of bypassing the mountainous lands we know today as Afghanistan.
Evidence of trade can be traced back to long before the Silk Road – locally mined lapis lazuli stones somehow found their way to ancient Egypt, and into Tutankhamun’s funeral mask, created in 1323BC.
Jagged peaks, rough roads in Tajikistan, roof of the world
Besides mercantile exchange, the caravan routes were responsible for the sharing of ideas and Afghanistan was a major beneficiary. Art, philosophy, language, science, food, architecture and technology were all exchanged, along with commercial goods.
In fact, maritime technology would eventually be the area’s undoing. By the 15th century, it had become cheaper and more convenient to transport cargo by sea – a far from ideal development for a landlocked region.
Iran
The Ganjali Khan Complex, in Iran. Photo: Shutterstock
Thanks to the Silk Road and the routes that preceded it, the northern Mesopotamian region (present-day Iran) became China’s closest trading partner. Traders rarely journeyed the entire length of the trail, however.
Merchandise was passed along by middlemen who each travelled part of the way and overnighted in caravanserai, fortified inns that provided accommodation, storerooms for goods and space for pack animals.
The good, bad and ugly sides to visiting Chernobyl and Kiev
With so many wheeler-dealers gathering in one place, the hostelries developed into ad hoc marketplaces.
Marco Polo writes of the Persian kingdom of Kerman, where craftsmen made saddles, bridles, spurs and “arms of every kind”.
Today, in the centre of Kerman, the former caravanserai building forms part of the Ganjali Khan Complex, which incorporates a bazaar, bathhouse and mosque.
Uzbekistan
A fort in Khiva, Uzbekistan. Photo: Alamy
The double-landlocked country boasts some of the Silk Road’s most fabled destinations. Forts, such as the one still standing at Khiva, were built to protect traders from bandits; in fact, the city is so well-preserved, it is known as the Museum under the Sky.
The name Samarkand is also deeply entangled with the history of the Silk Road.
The earliest evidence of silk being used outside China can be traced to Bactria, now part of modern Uzbekistan, where four graves from around 1500BC-1200BC contained skeletons wrapped in garments made from the fabric.
Three thousand years later, silk weaving and the production and trade of textiles remain one of Samarkand’s major industries.
Georgia
A street in old town of Tbilisi, Georgia. Photo: Alamy
Security issues in Persia led to the opening up of another branch of the legendary trade route and the first caravan loaded with silk made its way across Georgia in AD568.
Marco Polo referred to the weaving of raw silk in “a very large and fine city called Tbilisi”.
Today, the capital has shaken off the Soviet shackles and is on the cusp of going viral.
Travellers lap up the city’s monasteries, walled fortresses and 1,000-year-old churches before heading up the Georgian Military Highway to stay in villages nestling in the soaring Caucasus Mountains.
Public minibuses known as marshrutka labour into the foothills and although the vehicles can get cramped and uncomfortable, they beat travelling by camel.
Jordan
Petra, in Jordan. Photo: Alamy
The location of the Nabataean capital, Petra, wasn’t chosen by chance.
Savvy nomadic herders realised the site would make the perfect pit-stop at the confluence of several caravan trails, including a route to the north through Palmyra (in modern-day Syria), the Arabian peninsula to the south and Mediterranean ports to the west.
Huge payments in the form of taxes and protection money were collected – no wonder the most magnificent of the sandstone city’s hand-carved buildings is called the Treasury.
The Red Rose City is still a gold mine – today’s tourists pay a hefty
. The Nabataeans would no doubt approve.
Venice
Tourists crowd onto Venice’s Rialto Bridge. Photo: Alamy
Trade enriched Venice beyond measure, helping shape the Adriatic entrepot into the floating marvel we see today.
Besides the well-documented flow of goods heading west, consignments of cotton, ivory, animal furs, grapevines and other goods passed through the strategically sited port on their way east.
Ironically, for a city built on trade and taxes, the biggest problem Venice faces today is visitors who don’t contribute enough to the local economy.
A lack of spending by millions of day-tripping tourists and cruise passengers who aren’t liable for nightly hotel taxes has prompted authorities to introduce a citywide access fee from January 2020.
Two thousand years ago, tariffs and tolls helped Venice develop and prosper. Now they’re needed to prevent its demise.
Source: SCMP
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