SARS could become a global epidemic if adequate control measures are not taken, two groups of scientists warned Friday in an influential medical journal, but stringent control measures can stop the disease if deployed in time.
The papers, published on the Web site of the journal Science, appeared on a day of mixed news that underlined the continuing unpredictability of severe acute respiratory syndrome.
Twenty new SARS cases cropped up in Toronto, weeks after Canada's last case of SARS was recorded. Emergency rooms throughout the city were forced to operate under special restrictions that limit access. Hundreds of people have been advised to go into a 10-day quarantine in case they were exposed.
''It's been a rough day,'' said Dr. Donald Low, a microbiologist and major figure in the city's anti-SARS efforts.
In response, the Centers for Disease Control and Prevention in Atlanta renewed a travel alert for Toronto that it had dropped earlier this month, warning travelers to take extra precautions that include avoiding hospitals and practicing frequent hand washing.
Simultaneously, the World Health Organization dropped its long-standing advisory against travel to Hong Kong and Guangdong, China, the two hot spots for SARS in Asia.
There was no such good news for Taiwan. The island nation reported an additional 55 cases overnight, bringing its total to 538 cases out of more than 8,100 worldwide.
Dr. Chesley L. Richards Jr., a CDC epidemiologist from Marietta who may have been infected with SARS while advising Taiwan on controlling its outbreak, boarded an air-ambulance flight in Taipei on Friday morning along with three CDC colleagues. Richards wore protective gear --- gown, hair covering, mask and eye shield --- and walked onto the plane under his own power, the CDC said.
The plane, a Gulfstream small jet that normally holds up to 20 people, was expected in Atlanta on Friday evening or this morning, CDC spokesman Llelwyn Grant said.
All four employees will be taken to an Atlanta hospital for evaluation. The three accompanying Richards, who have not shown symptoms, will be allowed to go home once they are checked by a CDC physician but will be monitored by the Georgia Division of Public Health.
Richards, an infection control expert who had been working in hospitals in Taipei, developed a low fever Monday, recovered, and then experienced a return of fever and cough Thursday. His condition did not change during the flight Friday, Grant said.
Richards will be placed in an isolation room --- a special hospital room rigged so that the air within it does not flow into the rest of the hospital --- and treated by employees in protective gear until his symptoms clarify, Grant said.
The CDC declined to say Friday in which Atlanta hospital Richards would be treated. The agency has a long-standing but informal relationship with Emory University School of Medicine, which operates Emory University, Emory Crawford Long and Wesley Woods hospitals.
Emory University Hospital declined to say whether Richards would be treated there.
Stringent precautions are a key feature in controlling any future spread of SARS, two teams of researchers said in the papers published Friday. Both groups used mathematical models to predict possible spread of the disease. One group, from the United States and Canada, said that early detection and isolation of cases, along with quarantine of suspected cases, could significantly slow the spread of SARS. The second group, from England and Hong Kong, argued that such efforts have already proved their usefulness, by reducing the once-explosive spread of SARS in Hong Kong to the current trickle of several cases a day.
But still-unanswered questions about seasonality, survivors' degree of immunity and animal hosts for the disease could dramatically affect how SARS behaves in the future, the researchers warned.
Information from news services was used in this article.
Copyright 2003 The Atlanta Journal-Constitution