A mysterious disease that causes flulike symptoms and pneumonia moved quickly around the world last week after sickening dozens in Asia. More than 160 people in seven countries have fallen ill in the past few weeks, according to the World Health Organization (WHO), and at least four have died. Those numbers raise fears about a new and uncontrollable pandemic.
Researchers are frantically trying to determine the cause of Severe Acute Respiratory Syndrome (SARS), as WHO has dubbed the disease. Hospital workers appear to be most at risk, suggesting that close contact with a patient is required for an infection. But so far, scientists aren't even sure whether the infection is viral or bacterial--let alone how it spreads, or how best to treat and prevent it. Researchers have tried "a phenomenally large range" of diagnostic tests on available samples, says Klaus Stöhr, an influenza expert at WHO in Geneva, but they have all been negative. "We really have to start from scratch and put all our assumptions aside" in the search for a culprit, he says.
Early symptoms include high fever, muscle aches, sore throat, and headache, sometimes followed by pneumonia and acute respiratory distress. "It sort of screams flu," says Brian Hjelle, a virologist at the University of New Mexico, Albuquerque. Indeed, some initially thought that the epidemic might be linked to a small outbreak of a virulent bird flu strain, called H5N1, which killed a man from Hong Kong last month and sickened his 9-year-old son (Science, 7 March, p. 1504). But no such link has been found, and most scientists say that if the disease were influenza, doctors would have recognized it by now.
Other potential candidates include a human parvovirus, or something resembling Nipah, a paramyxovirus that triggered a fatal outbreak among pig farmers in Malaysia in 1999, says C. J. Peters, director of the Center for Biodefense at the University of Texas Medical Branch in Galveston. Having studied deadly outbreaks in many corners of the world, Peters says, "I don't know one that has left me with such a feeling of danger."
At the same time, the new outbreak puts public fears of bioterrorism and ballooning biodefense budgets into perspective by reasserting the impact of naturally occurring diseases, says Marjorie Pollack, who is monitoring the outbreak for ProMED, a worldwide electronic reporting system. Says Pollack: "Mother Nature is by far the worst bioterrorist out there."
With reporting by Gretchen Vogel in Berlin.