It’s been a decade since severe acute respiratory syndrome, widely known as SARS, swept through Asia and beyond, killing some 775 people and raising fears of a global pandemic.
Now health officials are expressing alarm about a similar virus -- called novel coronavirus -- that emerged on the Arabian peninsula last autumn.
"The virus is from the same family as both the common cold virus and SARS virus," Gregory Hartl, an epidemic diseases expert with the World Health Organization (WHO) in Geneva, says. "This virus is slightly different to both of those. It seems for the moment to be less transmissible than SARS and less transmissible than the common cold virus, and obviously more deadly than either of those two viruses, for the moment."
Established cases of the coronavirus are so far relatively few -- just 34 cases in Qatar, Saudi Arabia, Jordan, Pakistan, Britain, Germany, and France.
But the virus, which can cause severe pneumonia-like symptoms as well as damage to the kidneys and other organs, has killed more than half of those infected -- a far deadlier toll than that of SARS, which killed approximately 10 percent of sufferers.
The Big Question
The source of the novel coronavirus is still unknown, although it is believed to have originated in animals, possibly bats, goats, or camels.
But health officials say the coronavirus, like SARS, also appears to be capable of human-to-human transmission, something that makes it far easier to spread.
Concerns about human-to-human transmission were heightened this weekend when officials in France confirmed that a hospital patient had contracted the virus after sharing a room with a man who fell ill after traveling to Dubai and was later diagnosed with novel coronavirus.
A picture from the British Health Protection Agency shows the "coronavirus" under an electron miscroscope.
Airborne transmission means the virus poses a potential threat to anyone who comes in contact with a coronavirus sufferer for a significant period of time.
But Hartl says the virus is not capable of infecting entire communities at once.
"You have to be a caregiver, basically, or someone who has an extended amount of close contact with a person to contract this disease," Hartl says. "If you're walking down the street and passing someone with this disease, it's highly, highly unlikely that you can get this. And that's what we mean, that this virus doesn't spread in the general community."
Still, the surfacing of a new virus has raised worries of a new SARS-style illness with the power to kill hundreds or even thousands of people.
The WHO has called novel coronavirus an "important and major challenge," and has issued a series of guidelines on preventing the spread of the disease, including frequent hand-washing and the use of face masks around infected patients.
The coronavirus scare comes amid fresh reports of another deadly virus, avian flu, in China. The outbreaks have sparked fears that the world’s population may be vulnerable to a global pandemic in an era when viral outbreaks appear more frequently and plane travel can transmit diseases to all points of the globe in just days.
But Hugh Pennington, an emeritus professor of bacteriology at the University of Aberdeen, Scotland, says the appearance of novel coronavirus is cause for concern but not panic.
He says it’s not that there are more viruses or that 21st-century globe-hopping is to blame for their spread.
"People have been moving internationally for thousands of years," Pennington says. "So I’m more inclined to the view that these viruses are out there and that we find them quite readily because we have better techniques for identifying them. And we are also more aware of them because of [journalists] like yourself."