The mysteries of testing, treatment and transmission
Kelly Crowe | April 25, 2003
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SARS is scaring a lot of people these days, and not just in Toronto. There are many questions about the mysterious virus; like what kind of illness SARS is, how it spreads, and how worried we should be about getting it. At times, all these questions and the answers can seem overwhelming. But for such a new illness, scientists have learned quite a bit about SARS.
For almost two months now, people have been washing their hands raw in the city of Toronto. From old to young, they've been following doctors' orders, doing the best they can to fight the invisible enemy that is SARS. But what exactly is it that they're trying to wash away? What do we really know about SARS?
"I think the healthiest place for me to be is on the bicycle riding around, you know, by myself. It's only in the elevators where I get a little scared kind of thing," says bicycle courier Robert Anderson.
"It's scary. I don't know. They don't know. They haven't, I guess, figured out exactly what it is, so I'm just going to try to keep as low a profile as possible while this is going on," says one man.
Here's what we do know:
It's a brand new virus, probably from an animal, but nobody knows which one. It spread fast enough to infect people in 25 countries in just six months. It's good at jumping from human to human. It makes healthy people very sick, and it can kill. It's potentially more deadly than the 1918 flu pandemic, one of the worst the world has ever seen.
One of the things we don't know yet is can it be stopped?
The grim answer to that is probably not, according to Allison McGeer, infectious disease expert and SARS survivor. She spoke to CBC News from home where she's still in quarantine, and she says what many health experts have been reluctant to say: that SARS will probably spread around the world; it's just a matter of time.
"If we don't have a vaccine, yes, we're all going to get it," McGeer says. "The better our containment strategies is, the more we delay it infecting everybody. But with viruses that are this transmissible
containment strategies will delay, but they won't ultimately stop the process."
There are three big problems. When people get SARS, doctors don't know how to treat it. They're trying a variety of things, but so far, no one knows if anything is working. There is also no vaccine to prevent it and no way to test people to see if they have it this despite encouraging reports that a test has been developed in record time. But right now, that test is really only good for research.
"The performance as a diagnostic test by using this PCR (polymerase chain reaction) test for coronavirus genes is very poor," says Health Canada's Dr. Frank Plummer. "We find that less than half of those with probable and suspect SARS are positive, and we find quite a few people who are neither probable or suspect SARS positive. So its performance as a diagnostic test is very poor."
Without a test, there's no way to know quickly who has the disease.
At the Toronto public health offices, they're trying to help people diagnose themselves, but for many people, it's hard to tell at first if they have SARS. The fact is the symptoms for many people are quite mild headache, muscle ache, maybe a slight sore throat.
"You know what? They're pretty common symptoms. Yeah, some days I've had a headache and some days I've felt tired, and I have to admit one night I came home and made sure I took my temperature, but other than that, yeah, nothing out of the ordinary," says Jan Smith of the Toronto Public Health service.
So how do you know if you have it? The fever is the key. But the fever is often not bad enough to keep people home from work, not for the first few days at least. Allison McGeer has talked to about 50 patients and experienced the symptoms firsthand.
"One of the important things at the moment about knowing if you have it is understanding whether you're at risk, and that's why we're working so hard at identifying people who have been exposed so that we can warn them. Because at least the beginning of the disease is very non-specific," she says.
Mild symptoms complicate everything. If people don't realize they have it, they won't be able to isolate themselves in time, and they could infect other people. That's what these Toronto health officers are trying to prevent. Every time they learn that someone has SARS, they try to track down every other person that might be at risk.
Scientists still don't know how easily the infection is spread. They believe it is spread by droplets released by coughing and perhaps during close conversation. But what about other body fluids?
Dr. Claus Stroh, the scientific head of the World Health Organization's SARS team, points to other missing pieces of the puzzle. "For how long is the virus excreted? Would the disease be excreted in fluids suffice enough to affect other patients?"
Scientists still don't know which body fluids are dangerous. And there's another important question: If you get SARS once, can you get it again? They believe it's possible.
"Still, that's another item for the list of the unknowns. We have seen that the overwhelming number of patients who had SARS develop antibodies," Stroh says. "It looks as if these are neutralizing antibodies, i.e., antibodies which would kill the virus and clean it from the body of the patients. We don't know what's happening after six months. Will the antibody last? Is it going to fade? All these are questions which can only be looked after over time."
Can you get SARS from touching something? That is still unclear. It depends how long the virus can survive on a surface. Until a few days ago, scientists were pretty sure it would only live for a few hours. Now it looks like it can survive on a dry surface for a whole day.
"The virus is available, it's still there after this period of time," Stroh says. "What we don't know yet is, if the amount of virus which remains after 24 hours will suffice to infect someone. We still don't know what the infectious doses, i.e., how many viruses have to be incorporated in to a susceptible person to cause this. All these are unknowns."
Healthy young adults at risk
Allison McGeer says she had only what she says was a mild case, yet she ended up in hospital.
"Think about an illness that an otherwise relatively healthy young adult needs to spend a week in the hospital. It was very unpleasant. I wouldn't recommend it to anybody, and yet my case was really mild, okay?" she says.
One other sobering aspect of the disease is its effect on young and healthy adults. It's bad enough that it will make someone sick for a month and even send them to hospital. Worse is the fact that scientists believe it will kill people between 25 and 40 at a rate of at least one per cent. That doesn't sound like much, but right now, nothing is that deadly to that age group.
"But the truth of the matter is that the death rate in the 1918-19 influenza pandemic, which is the single worst infectious disease episode in the world, the death rate in 25 to 40 year olds was one per cent," McGeer says. "So we're looking at a disease that has a higher death rate. Most people have read stories about the 1918-1919 pandemic and how awful it was, and we're talking about a disease that potentially has a higher mortality rate in healthy adults than that disease."
Containment is crucial
So without a diagnostic test, a vaccine, or a treatment, the hope now lies in a strategy that is centuries old quarantine and containment. WHO scientists say it worked in the 13th century, so it could work again now.
"We're back to the time when antimicrobials, vaccines and others were not available," Stroh says. "Even at those times, disease could be efficiently controlled. The plague in Venice in the 13th century could be controlled by isolation, and I would believe that under our current circumstances, we are in at least as good a position as a couple of hundred years ago."
That's why all the containment strategies are so critical, and that's why the WHO feels it needs to even contain the city of Toronto. There are already examples of people catching SARS here and taking it somewhere else the world. So containing it here is an important part of containing it everywhere.
The good news is containment has worked in some countries.
"In the U.K., like in Italy, like in Germany, the number of cases is on the decline," Stroh says. "Contact tracing is efficient, and the number of deaths is relatively small, it's very small. So this is sufficient food for hope that the disease can be brought under control."
Do commuters need to worry about the subway? Not yet, the experts say. At this point, every case can still be traced to another known case, so people are not picking it up just by walking around. And there's no indication anyone is prepared to give up and let it just spread of its own accord.
"Should you be worried about getting SARS on the subway when you go to work today? No. The risk to the general population in Toronto at this precise instant is still very low, only barely higher than it was some time ago and only barely higher than it is in other places across the country," McGeer says.