By late last week, SARS had stricken scores of people in the Toronto area alone, causing several deaths and disrupting everything from air travel to medical services. The city’s hospitals, operating under “Code Orange,” suspended elective procedures and barred most visitors. Health workers who’d treated SARS patients stayed home in quarantine to protect the rest of the community. At Toronto’s Pearson International Airport, departing passengers received pink slips urging them to skip their flights and see a doctor if they or their contacts had suffered symptoms within the past 10 days. Despite such measures, the epidemic has grown steadily, reaching at least 18 countries, infecting more than 2,400 people and killing at least 89.
Is the worst yet to come? Health officials are racing to contain the new illness, and scoring some early victories. They have tentatively linked it to a novel coronavirus–a type of virus that normally causes only colds in humans–and they’ve shown that masks, gowns and the isolation of sick patients can slow the spread of the disease. But there is still plenty to worry about. Though most patients recover, SARS can kill a healthy adult in a matter of days. And unlike HIV or a hepatitis virus, it can travel via coughs and sneezes. Doctors still lack a reliable diagnostic test for the condition, let alone an effective treatment. And though most new infections have involved close contact with a sick patient, experts now fear the infection may spread by other means as well. As Dr. Julie Gerberding of the U.S. Centers for Disease Control and Prevention conceded last week, “It’s too soon to tell where all this is going to go.”
No one is even sure where exactly it came from, but all signs point to the southern Chinese province of Guangdong, which borders Hong Kong. Researchers have long marveled at how new cold and flu viruses emerge from Guangdong’s small farms, where birds, pigs and people live in close enough proximity to circulate and amplify whatever infections they harbor. Experts believe that many of the world’s flu epidemics are seeded in this rural province and relayed to the world on the jets flying in and out of Guangzhou and nearby Hong Kong. Doctors in Guangdong reported some 300 cases of severe atypical pneumonia last fall, but the Chinese government downplayed the problem until it had spread to Hong Kong and beyond, prompting an alert from the World Health Organization in mid-March. Finally last week, China acknowledged the extent of the problem and agreed to let a WHO team into Guangdong to investigate.
The team’s first task is to pinpoint the cause of the illness. Coronaviruses came under suspicion in mid-March, when researchers in several countries spotted the viruses’ crown-shaped forms in phlegm and other secretions. The suspicion grew stronger when researchers at the University of California, San Francisco, found gene fragments resembling those of an avian coronavirus in SARS patients. Coronaviruses circulate constantly among chickens, pigs, mice and cows, causing everything from encephalitis to liver disease, but they’ve never been linked to a serious human illness. Is SARS an exception to that rule? If researchers can link the disease to a specific viral agent, they’ll be able to stop worrying about “suspected” cases and develop reliable lab tests. Drugmakers, for their part, will have a target for treatments and vaccines.
But finding a virus isn’t the only challenge researchers face. They also need to determine exactly how it travels. In tallying Hong Kong’s 800-plus SARS cases over the past couple of weeks, researchers have traced more than 100 of them to a single building in a large housing complex. These people weren’t all caring for patients. So how did they contract the bug? Could it have been the plumbing? The air conditioning? Did rats spread the disease in their droppings?
Until those questions are resolved, no one can say precisely what precautions are called for. Besides isolating sick patients, a number of countries are now using quarantine to keep healthy but potentially exposed people from unwittingly infecting others. In practice, that usually means staying home for 10 days, and avoiding close contact with family members, but Hong Kong has gone a step further, moving 241 residents of the stricken apartment complex to a campground with holiday bungalows. The WHO, meanwhile, is urging people to cancel nonessential travel to affected parts of Asia. And in Toronto, ordinary people are taking whatever precautions they can. The city’s Dai Kuang Wah Herb Market still does a brisk business, but owner Mai Hoang and her staff now work behind surgical masks and gloves. She knows the garb is probably unnecessary, but her rationale isn’t hard to fathom. As she puts it, “You never know.”
