C Scientists say Severe Acute Respiratory Syndrome (SARS) is caused by a new virus from the family of corona viruses ( 冠状病毒 ), which also causes the common cold. WHAT ARE THE SYMPTOMS? The World Health Organization says the main symptoms of SARS are high fever (over 38 °C ), dry cough, shortness breath or breathing difficulties. Changes in chest X-rays, which are indicative of pneumonia ( 肺炎 ), also occur. SARS may be associated with other symptoms, including chills, headache, muscular stiffness, loss of appetite, malaise, confusion, rash and diarrhea. Health experts say the disease has an incubation period ( 潜伏期 ) of between two-to-seven days, with three-to-five days being more common, before victims start showing flu-like symptoms. HOW DANGEROUS IS IT? The mortality rate ( 死亡率 ) appears to be between 3 to 5 per cent. In Hong Kong, at least, those who infected invariably develop severe pneumonia, which can cause numerous complications. The victim's condition can deteriorate ( 恶化 ) very quickly in as little as five days. WHAT IS THE TREATMENT? There is currently no specific cure for the disease. But doctors worldwide have been treating it with ribavirin an anti-viral drug and steroids ( 类固醇 ). Doctors say if treated early most patients without other serious illnesses can recover. HOW DOES IT SPREAD? WHO ( 世界卫生组织 ) and Hong Kong experts say the virus spreads through droplets by sneezing or coughing and such direct infection ( 传染 ) can usually happen within a radius of around three feet. The virus can also spread indirectly as it can survive outside of the human body for three to six hours. Contact with any object that is tainted by droplets containing the virus, for example, a contaminated phone, could lead to infection if a person then touches their eyes, nose or mouth. Health experts have not ruled out that it could be airborne ( 空气传播的 ), which infinitely raises the contagious nature of the virus and would make it far harder to contain ( 控制 ).