SARS Epidemic Reaches Canada
"SEVERE acute respiratory syndrome" hardly rolls off the tongue with ease, but it may yet ingrain itself into the popular lexicon - not necessarily for its virulence, but for the lessons it offers. Judging by the initial indicators - and this can change - the planet may have caught a break this time. The mysterious respiratory disease has infected at least 350 people, mostly in Asia, and killed at least 10, including two Toronto residents. But SARS doesn't seem to be as deadly, nor spread as easily as, say, some highly infectious strains of INFLUENZA that have plagued the world. Nonetheless, the new syndrome could be a wake-up call. A couple of snags delayed the initial efforts of Canada's health authorities to combat the outbreak. While it's difficult to say what impact, if any, these problems may have, at the very least they underscore the need for vigilance at a time when the next killer flu pandemic is already long overdue.
The 20th century saw some terrible outbreaks, the Spanish flu in 1918 being notably vicious. As much as 40 per cent of the global population got sick, and more than 20 million people died. The Asian flu in 1957 and the Hong Kong flu in 1968 killed 700,000 worldwide. Other scares stopped short of reaching the pandemic stage: the swine flu at a New Jersey army base in 1976, 1977's Russian flu, and the avian flu outbreak in Hong Kong in '97. Another planetary plague is unavoidable, says Dr. Donald Low, chief of microbiology at Mount Sinai Hospital in Toronto, and one of the physicians spearheading efforts to control SARS in the city. "We're due now. There's a lot of concern."
All signs point to SARS not being that killer flu. Preliminary findings from labs in Hong Kong and Germany, though inconclusive, suggested the culprit might belong to a large family of viruses called paramyxoviridae that cause respiratory infections, mumps and measles. Building on the Hong Kong work, Health Canada scientists in Winnipeg then announced that six of the nine Canadian patients tested positive for metapneumovirus, a little understood member of the paramyxoviridae family usually associated with mild respiratory infections and with no known treatment. Whatever pathogenic agent is at work, the Geneva-based World Health Organization, an arm of the United Nations, saw fit to issue a rare global health alert on March 12, warning people to watch for sudden onset of fever above 38°C, coupled with respiratory symptoms that include cough, shortness of breath or difficulty breathing. On March 15, it issued an emergency travel advisory, counselling people worldwide to watch carefully for symptoms. Ottawa asked Canadians to reconsider non-essential travel to hot spots.
The WHO's alerts followed outbreaks of unusually severe pneumonia in Vietnam, Hong Kong and China's Guangdong province. The Chinese government, criticized for taking too long to alert the world, reported on March 16 that there had been 305 cases thought to be SARS in Guangdong dating from November. Five people died by the end of February, when that outbreak appeared to have burned itself out.
But SARS was now a global problem. By last week, cases had been reported in Canada, the United States, Britain, Germany, Switzerland, Spain, Slovenia, Thailand, Vietnam, Singapore, China and Taiwan. Patients were hospitalized in isolation units in Vancouver and Toronto. All had either recently returned from southeast Asia, or had been in close contact with someone who had. Epidemiologists in Hong Kong reported that seven people who contracted SARS - including two Canadians - stayed in or visited one particular hotel there last month. In Toronto, five cases occurred in one extended family, killing a 78-year-old woman who'd been to Hong Kong and her 44-year-old son, who hadn't. Treatment, once SARS is suspected, involves bombarding patients with broad-spectrum antiviral and antibacterial drugs. Hospitalized victims in Canada have done well, but it is unknown whether they responded to treatment, or whether the syndrome simply ran its course and they got lucky.
Close personal contact seems to be the key risk factor. The WHO defines close in this case as "having cared for, having lived with, or having had direct contact with respiratory secretions and body fluids of a person with SARS." Jet travel has facilitated the syndrome's spread around the globe, but SARS didn't infect people easily, the new cases often being family members or health-care workers treating patients. Dr. Frank Plummer, scientific director of the National Microbiology Laboratory in Winnipeg, Health Canada's most secure lab, advises the public to pay particular attention to washing their hands. "The fact that it seems to require very close personal contact for it to be transmitted," says Plummer, "suggests that it will be quite easy to control."
But what if it weren't so easy? What if SARS had turned out to be the next killer flu? Quick action in any serious outbreak is critical for controlling the spread of disease. In the early goings of the SARS cases in Toronto, Health Canada officials lost critical hours as they tried to find out which plane one of the victims had taken from Hong Kong, delaying notification of the other passengers. "There was a problem in identifying the flight of the Toronto woman who died because most of the rest of her family was sick," Plummer explains. "The information just wasn't available." Three flights were ultimately identified as carrying infected passengers. But it still wasn't just a simple matter of picking up the phone and dialing people on the passenger lists. Those lists are typically coded in different ways by various airlines, and may take considerable time to decipher. "The passenger manifests are in a very dense code that has to be translated," says Plummer. "It's a very laborious process."
The U.S. had its own scare in 1976. The swine flu that broke out at Fort Dix, N.J., appeared to be related to the deadly 1918 Spanish pathogen. Ultimately, it killed just one soldier, but the lessons of that outbreak resonate still. Washington, fearing a dreadful pandemic, ordered that every American be vaccinated. But it was not as easy as that.
First, the manufacturer agonized over being held liable for side effects. The vaccine took longer than expected to reach the public. Then it turned out that it didn't fully protect children. Beset by controversy, the campaign lurched to a standstill after about a fifth of the U.S. population had been vaccinated. Some doctors suspected the vaccine was linked to a paralytic disease called Guillain-Barré syndrome, which killed 32 people. "This thing probably wasn't going to become a pandemic anyhow," says Low, "but it shows you the politics and the difficulty in making decisions about what you're going to do to protect the population."
The next viral threat, when it comes, will likely arise in densely populated Asia. Outbreaks tend to follow a pattern. Ducks, geese and chickens host viruses, which get passed on to swine. The viruses then encounter others in the pigs and swap their DNA, creating new viral agents. Because pigs are genetically similar to humans, the new virus can fairly easily make the jump. In many parts of Asia, birds, pigs and humans live in close quarters, facilitating this genetic genesis. "If it happens to be an influenza virus that we've had no experience with, that is we don't have any antibodies," says Low, "we can be shit out of luck."
There have been some recent close calls. In 1997, several hundred people in Hong Kong contracted the influenza A(H5N1) strain carried by birds. Unlike other flu viruses, this one skipped the pig stage and went directly to humans. Eighteen people were hospitalized in '97 - six died. Mercifully, this avian flu did not easily spread from one person to another. Health authorities slaughtered all of the city's chickens - about 1.5 million in all - to curb the virus's spread.
Another chilling incident came just last month, when the bird flu killed a man in Hong Kong. This time it didn't spread. When the big one does hit, says Low, at least there's comfort in knowing that medicine has come a long way since 1918. "Now we've got antibiotics, better health care, and vaccine protection against many of the pathogens that would normally cause secondary infections," he says. "We are in a better state of health." Unfortunately, viruses and bacteria have proven adept at finding new ways of sabotaging our defences.
See also EPIDEMIC.
Maclean's March 31, 2003