Health experts are holding an emergency international meeting to devise ways of combating a mysterious virus that has been described as the world's single biggest threat to public health.
Middle East Respiratory Syndrome (Mers) has already claimed 38 lives, mostly in Saudi Arabia, and bears a striking similarities to Sars, which killed around 800 people in 2003.
Amid fears of a global pandemic, 80 officials and doctors gathered in Cairo yesterday.
The three-day meeting called by the World Health Organisation will look at developing guidelines for the annual Muslim pilgrimages to Saudi Arabia, where four new deaths were announced on Monday.
The virus appears to have a 12-day incubation period, meaning that pilgrims could return to their home countries without realising they have caught it.
Three cases have been recorded in Britain, with others in France, Germany, Italy, Tunisia and Jordan.
Scientists remain baffled about the source of the virus, which was first reported in April last year. The symptoms are similar to Sars, with an initial fever and cough that develops into pneumonia. It has a fatality rate of 60 per cent.
Dr Jon Bible, a clinical scientist who treated one of the British patients last year, said: "You don't want to have this."
Sufferers "are very close to death at all times. They are in respiratory distress at all times, it's like a very serious pneumonia," he added.
His patient at St Thomas' Hospital in London survived after several months of artificial respiration but still has breathing difficulties.