'A threat to the world'
The World Health Organisation has branded the SARS-like virus that has killed 27 people - mainly in Saudi Arabia - as a threat to the entire world.
The warning came as a new study showed that the Middle East Respiratory Syndrome coronavirus may have an incubation period - the time between infection and symptoms - of nine to 12 days, longer than the one-to-nineday period previously observed.
This finding had "important implications for the duration of the quarantine required to rule out infection among contacts" of the patient, said the study in The Lancet medical journal.
The disease is a cousin of Severe Acute Respiratory Syndrome, which sparked a global health scare in 2003 when it leapt from animals to humans in Asia and killed about 800 people.
W H O 's director-general, Margaret Chan, said the virus was her greatest health concern.
Speaking in Geneva, Chan called the ongoing outbreaks "alarm bells" and said the virus "is a threat to the entire world".
According to The Lancet study, people who return from the Middle East with respiratory ailments, or who had been exposed to a confirmed case of the virus, should be isolated. The researchers have recommended a period of at least 12 days to confirm they were clear of the virus.
A team of researchers had examined two French patients for the latest study.
One, who has since died, was apparently infected while travelling in Dubai, and the second seems to have caught it while sharing a hospital room with the first - before doctors detected the virus.
Yesterday, WHO said the global death toll from the virus had risen to 27, after three patients died in Saudi Arabia in addition to the death in France.
Like SARS, the new virus appears to cause a lung infection, with patients suffering from a temperature, cough and breathing difficulty. But it differs from SARS in that it also causes rapid kidney failure.
Health officials have expressed concern about the high death rate of about 50%, warning the disease could spark a new crisis if it acquires an ability to spread easily between humans.
In the study, the authors say the occurrence of "clusters" of infection was a worrying development.
"It might result from adaptation of the virus to inter-human transmission," they wrote.