Coronaviruses are a large family of viruses which include the common cold and Sars (severe acute respiratory syndrome). They cause respiratory infections in humans and animals, with four or five strains currently affecting humans. They are a species in the genera of virus belonging to the subfamily Coronavirinae in the family Coronaviridae.
Source of deadly Middle East virus remains a mystery
Mers, which has claimed 38 lives, spreads between people and is more deadly than Sars
A mysterious new respiratory virus that originated in the Middle East spreads easily between people and appears more deadly than Sars, doctors reported after investigating the biggest outbreak in Saudi Arabia.
More than 60 cases of what is now called Mers (Middle East respiratory syndrome), including 38 deaths, have been recorded by the World Health Organisation in the past year, mostly in Saudi Arabia. So far, illnesses have not spread as quickly as Sars (severe acute respiratory syndrome) in 2003, which triggered a global outbreak that killed 774 people, including 299 in Hong Kong.
An international team of doctors who investigated nearly two dozen cases in eastern Saudi Arabia reported on Wednesday that the new coronavirus has some striking similarities to Sars. However, scientists remain baffled as to the source of Mers.
In a worrying finding, the team said, Mers not only spreads easily between people, but within hospitals. That was also the case with Sars, a distant relative of the new virus.
"To me, this felt a lot like Sars did," said Dr Trish Perl, a senior hospital epidemiologist at Johns Hopkins Medicine, who was part of the team whose report was published online in The New England Journal of Medicine.
Perl said they couldn't nail down how it was spread in every case - through droplets from sneezing or coughing, or a more indirect route. Some of the hospital patients weren't close to the infected person, but somehow picked up the virus.
"In the right circumstances, the spread could be explosive," said Perl, while emphasising that the team had only a snapshot of one Mers cluster in Saudi Arabia.
Cases have continued to trickle in, and there appears to be an ongoing outbreak in Saudi Arabia. Mers cases have also been reported in Jordan, Qatar, the United Arab Emirates, Britain, France, Germany, Italy and Tunisia. Most had a connection to the Middle East.
In the Saudi cluster that was investigated, certain patients infected many more people than would be expected, Perl said. One patient who was receiving dialysis treatment spread Mers to seven others, including fellow dialysis patients at the same hospital. During Sars, such patients were known as "superspreaders".
Perl and colleagues also concluded that symptoms of both diseases are similar, with an initial fever and cough that may last for a few days before pneumonia develops.
But Mers appears far more lethal. Compared with the 8 per cent death rate for Sars, the fatality rate for Mers in the Saudi outbreak was about 65 per cent.
While Sars was traced to bats before jumping to humans via civet cats, the source of the Mers virus remains a mystery.
Doctors around the world have struggled to treat patients. "We need more information from other countries to find out what the best treatment is," said Dr. Clemens Wendtner, who treated a Mers patient who later died in Munich despite the best medical care available.