As public-health officials worldwide end a second week of efforts to quash the spread of a previously unknown illness traced to Asia, bioterrorism specialists are watching their progress for lessons that might be applied to the aftermath of a bioterror attack.
Indeed, the public-health response, particularly in the United States, already appears to have incorporated lessons learned from anthrax-filled letters mailed in the fall of 2001, several experts say.
The outbreak of severe acute respiratory syndrome (SARS) has shown that "pathogens do not recognize political boundaries," says David Heyman, a bioterrorism specialist at the Center for Strategic and International Studies in Washington, D.C. "You need a global response to bioterrorism, not just a domestic one." In that respect, he adds, "This is a great test case."
As cases popped up from China to Canada, World Health Organization (WHO) officials linked a network of 11 laboratories in nine countries to identify the agent causing the illness and devise treatments, says Julie Hall, a WHO medical officer. She characterizes the current collaboration as "unprecedented."
At week's end, WHO, which is based in Geneva, had gathered reports of 1,323 cases of SARS in 13 countries, and attributed more than 50 deaths to the disease since it was first recognized in Hanoi on Feb. 26. Chinese officials have identified more than 700 cases in the country's southern province of Guangdong.
Hong Kong has tallied 316 cases, while Singapore has identified 74. Six European countries, as well as the US and Canada, have also reported cases.
In response, Singapore this week closed schools to keep the outbreak from spreading to the city-state's 500,000 school children.
Earlier this month, Singapore public-health officials imposed a strict 10-day quarantine of citizens who may have come in contact with people diagnosed with SARS. In Hong Kong, which has closed 100 schools, officials have adopted a similar quarantine for those who have had contact with SARS patients.
To reduce the risk to healthcare workers, doctors and nurses attending suspected SARS patients have been advised to wear gowns, gloves, masks, and even eye protection until the virus is identified and more is known about it.
Where possible, patients are isolated in special rooms with "negative air pressure" so that as doors open, air is pulled into the room and leaves through special exhaust systems.
The outbreak is thought to have begun in China's southern province of Guangdong in November. Researchers say the region has been a source of several previously unknown viral diseases, which emerge as the viruses evolve and jump from livestock to humans. From Guangdong, SARS moved into Hong Kong in February, and from there it extended its reach to Singapore, Vietnam, Thailand, as well as North America and Europe.
Using a range of high-tech tools - from electron microscopes to gathering "mug shots" of the suspects to DNA analyses - researchers say they have narrowed the list of suspected viruses to two types. In the US and Hong Kong, scientists' lead candidate is an new form of the virus researchers have associated with the common cold.
This has made it difficult to recommend treatments for SARS patients, epidemiologists say, because there is no effective antiviral medication to combat colds.
Still, narrowing the range of culprits to two represents significant progress say WHO researchers, who do not discount that the pair may also act in tandem to trigger SARS. Given the unknowns, public-health officials are confronted with a situation analogous to what some have called a worst-case bioterror attack.
"We have what looks like a new agent, airborne-spread through close contact, a higher-than-normal fatality rate, and no effective drug at the moment to contain it, which suggests physical containment or rapid screening of drugs to see if something will work," says Ronald Atlas, a microbiologist at the University of Louisville in Kentucky.
So far, according to some analysts, the public-health system has responded effectively to identify the source and potential medical remedies.
"Given the short time we've been exposed, I think it's been doing an incredible job," says Terri Rebmann, an infectious-disease specialist at the Center for the Study of Bioterrorism and Emerging Infections at St. Louis University in Missouri.
In the past, international laboratories have competed to solve an epidemiological challenge. But in this case, labs have been exchanging data on a daily basis. Lines of communication between research facilities, physicians treating cases, and the public have been strengthened.
And in the US, the Centers for Disease Control in Atlanta have sent virus samples to the Defense Department for screening against antiviral compounds the Pentagon may have developed as antidotes for biological-warfare agents.
The Defense Department and CDC are also working together to develop rapid tests that state and local public-health officials can use to quickly diagnose the condition.
Mr. Heyman of the CSIS cautions that while this outbreak will yield some useful lessons for bioterrorism defense, it still represents a "weak proxy." He notes that an intentional release is more likely to spread faster, since terrorists would likely introduce a pathogen in many locations simultaneously.
And while scientists responded swiftly once the virus emerged from China into Hong Kong, the outbreak languished in China months before without attention. Indeed, the Chinese government only gave a full accounting of the number of cases this week.
The world's "early warning system" needs to be improved, Heyman says. "This is demonstrating how challenging it will be if we have a real attack."