Mystery Illness's Mortality Rate 4%, WHO Official Says (washingtonpost.com)

Mystery Illness's Mortality Rate 4%, WHO Official Says (washingtonpost.com) SARS, which emerged in southern China in November, has spread to at least 13 countries in Asia, Europe and North America, sickening more than 1,300 people and killing at least 49. U.S. health officials are investigating 45 possible cases in 20 states, including three in Virginia.

A distinctive pattern of symptoms has become clear, Salter said. Two to seven days after being exposed, patients suddenly develop a high fever -- 104 degrees Fahrenheit or higher -- start shaking and experience chills, shortness of breath and a dry cough. Some also experience headache, muscular stiffness, loss of appetite, malaise, confusion, rash and diarrhea.

Laboratory tests show that white blood cell and platelet counts drop in some patients. Chest X-rays usually reveal a distinctive pattern in which a cloudy area appears in one part of a lung and then spreads across both lungs.

After about six or seven days, about 80 percent to 90 percent of patients begin to improve. The remaining 10 percent to 20 percent deteriorate and require intensive care, with many needing a mechanical ventilator to help them breathe.

About 40 percent to 50 percent of those patients die, making the overall mortality rate for the disease about 4 percent.