Richard Schabas was Ontario’s chief medical officer of health from 1987 to 1997. Neil Rau is an infectious diseases specialist and medical microbiologist in private practice in Oakville, Ont., and a University of Toronto lecturer.
The Ebola outbreak in West Africa is unprecedented. There are far more cases than in previous outbreaks of the virus. The geography is different – West Africa instead of the Congo Basin. It is lasting longer and showing no signs of waning.
The fear has triggered global alarm, all of which should feel like déjà vu to Canadians who remember the 2003 SARS outbreak in Toronto.
Knowledge is our best weapon against such diseases. SARS could only be spread efficiently by severely ill patients, most often in hospitals. It was eliminated by the simple expedient of isolating any and all hospital patients with pneumonia.
With that in mind, here are four key things to know about Ebola:
1. It’s fundamentally spread from animal to human, not human to human.
Ebola is a disease of animals that can occasionally infect humans – technically called a zoonosis. A person who is severely ill with Ebola can spread the infection to other humans by close contact with blood and body fluids. This puts caregivers at risk – both in households and in resource-poor hospitals. But crucially, Ebola cannot spread efficiently between humans and cannot cause sustained human-to-human outbreaks, even to the limited extent that SARS could.
This is an animal outbreak, with humans as collateral damage. The driving force is new infections acquired from animals. Human-to-human outbreaks are short-lived. This is not a single human outbreak starting from a “case zero.”
The specific animal reservoir for Ebola is unknown but is probably a jungle animal used for food, known as “bush meat.” The large number of cases in West Africa must be the result of more human contact with infected animals, either because there are more infected animals or because they are consumed or hunted more aggressively in West Africa than elsewhere. While identifying a specific animal host would certainly aid in prevention efforts, bush meat remains an important source of dietary protein and won’t be abandoned overnight as a food source. Ebola is a disease of poverty – a potentially deadly meal is better than no meal at all.
2. Unlike SARS, this outbreak won’t end quickly.
This is bad news for West Africa, which should expect a steady stream of new human infections. Outbreaks may well appear in other parts of equatorial Africa. The animal epidemic will eventually wane and with it the human outbreak, but the timeline for this is anyone’s guess – weeks or much longer. In the meantime, prompt identification of new cases and better infection control in rural hospitals will reduce the risk of human-to-human spread, but even these measures won’t stop the outbreak altogether. Experimental treatments are a distracting fantasy. Vaccine development will take years.
3. Quarantine was abandoned a century ago.
There is an essential difference between quarantine and case isolation. Quarantine targets well people potentially incubating an infection; it’s impractical, ineffective and economically disruptive. Case isolation, on the other hand, targets individuals showing symptoms of disease and is the cornerstone of effective infection control.
Quarantine didn’t help control SARS and it won’t help control Ebola. Because of fear of Ebola, whole areas of West Africa are being cordoned off and airlines are cancelling services. These are forms of quarantine. They will hinder the flow of aid without stopping the disease’s spread.
4. Ebola may cause a scare, but it can’t cause an outbreak in Canada.
Occasionally apparently well people incubating Ebola infection will travel to other countries, as they have already to Nigeria. These travellers may even infect a few unfortunate contacts, including health-care workers. But they cannot and will not trigger sustained outbreaks as occurred with SARS. In Canada, it’s unlikely that we will see any cases of Ebola at all. It’s not a meaningful threat to Canadians unless we travel to specific regions in Africa. Still, it’s reasonable for our hospitals to keep out a watchful eye for infected travellers to protect our front-line health-care workers.
Canada can help West Africa by providing hospital infection control equipment and expertise, opposing quarantine and supporting the World Health Organization’s efforts to control Ebola. Our experience with SARS should teach us that a rational, balanced response is best.Report Typo/Error
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