Bats are original carriers of Sars virus

This story was first published in The Straits Times on Dec 1, 2013

It's final. A decade after the Sars outbreak killed close to 800 people worldwide, scientists have fingered bats as the original carriers, or "reservoirs", of the disease that later jumped to humans.

They are also the likely culprits behind the deadly Mers (Middle East Respiratory Syndrome) virus sweeping the region.

Singapore scientist Wang Linfa, a key member of the research project, is convinced that bats will be the source of another infectious disease outbreak.

"I am almost certain that in the next 10 years, a new killer virus spread by bats will emerge," said Professor Wang, director of the Emerging Infectious Diseases programme at Duke-NUS Graduate Medical School Singapore.

Though they can rapidly spread pathogens that can kill humans, bats somehow seem unaffected by viruses such as Ebola, Sars and Nipah. They also seem a lot hardier and live three to 10 times longer than their wingless counterparts of a similar size, such as mice.

"Sars and Mers can both kill, so the 20 to 30 known closely related viruses in between them on the coronavirus tree would be expected to have the potential to kill too," said Prof Wang, who is also with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Australian Animal Health Laboratory.

"And we're just scratching the surface here, there are over a thousand bat species each carrying different diseases."

Researchers have shown previously that bats are natural reservoirs of Sars-like coronaviruses. But this is the first time that a live virus has been successfully isolated from bats to definitively confirm them as the origin of the virus, said CSIRO Australia in a statement.

The latest discovery that bats may infect humans directly has enormous implications for public health control, said the international research team behind the effort, led by Professor Shi Zhengli from Wuhan Institute of Virology, Chinese Academy of Sciences. Its findings were published recently in the journal Nature.

The scientists are still trying to work out how the virus would be transmitted directly from bats to humans, but it could be through the dust of the faeces, or through close contact when hunting or eating the bats.

Their work on faecal samples taken from Chinese horseshoe bats will allow them to conduct detailed studies to look at how to thwart outbreaks and develop vaccines.

However, team member Peter Daszak, president of New York-based EcoHealth Alliance, warned: "Our research uncovered a wide diversity of potentially pandemic viruses present, right now, in bats in China that could spill over into people and cause another Sars-like outbreak.

"Even worse, we don't know how lethal these viruses would be if such an outbreak erupted."

Prof Wang noted that hospitals see patients with undiagnosed infectious diseases that have unknown causes on an almost daily basis, and fighting a virus is like fighting terrorists, he said.

"It is unpredictable, there are huge consequences, and you are working in the dark," he said. "So training infectious diseases researchers is like training an army. The strategy is to invest during peacetime so we can be ready when war hits."

To this end, Prof Wang and his team have received multimillion- dollar funding from the Singapore Government to continue to monitor and study bat cell biology, and develop better ways of detecting and fighting diseases.

He wants to bring in special black flying fox bats from Australia to establish a breeding colony, which will greatly build up the quality and capability of bat research here.

Prof Wang, who is quick to point out that he is the "bat virus man", not "bat man", has won numerous scientific awards for his influential work in isolating and studying many deadly bat-borne viruses including Hendra (which he named), Nipah and Sars.

His ground-breaking studies of bat viruses contributed to the Hollywood medical thriller Contagion, in which a bat virus is transmitted to humans.

"This research won't have a translational impact over the next few years. But in 20 years, who knows? Imagine if we can unlock the mysteries of longevity," he said.

This story was first published in The Straits Times on Dec 1, 2013

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