The recent Ebola scare in Canada

While you may think that Africa is half a world away, it might be closer than you think. There was the possibility of a case of Ebola in Canada recently. Fortunately, lab tests showed that the patient did not have Ebola.

Ebola virus, a hemorrhagic fever virus, was first detected in the 1970s in Zaire.

In the interim, there have been sporadic outbreaks of Ebola, primarily in Africa. There are several subtypes of Ebola. Some more deadly than others.

Ebola Zaire has killed anywhere from 60-100% of its victims. Right now, an Ebola outbreak is going on in Africa. In Guinea, and possibly a few surrounding countries, about 100 people are thought to be infected. Ebola Zaire has been confirmed in several of those patients. Current estimates are that about 60 people have died in the area. Relief workers from groups like Doctors Without Borders are on site trying to set up quarantine facilities and to begin treating the ill.

Ebola 101


The Ebola virus, courtesy of the CDC.

Ebola can start off with fever and flu-like symptoms, muscle aches, sore throat, headache, cough, nausea, vomiting and similar symptoms. Hemorrhaging also occurs. The bleeding occurs primarily from the gastrointestinal tract, but there can be bleeding from the lungs, bleeding into the skin and bleeding from other sites as well.

The virus can be transmitted through blood, body secretions, possibly through large respiratory droplets (from coughing and sneezing), from contact with bodies of those who died from Ebola and the virus can even be passed through semen. The reservoir (natural host of the virus) was unknown for a long time. It’s now thought to be the fruit bat. Though is some evidence that it can live in pigs, as well.

Often some of the first people infected during an outbreak are health care workers. In Africa, the initial symptoms of Ebola resemble malaria, and health care workers treat malaria patients without any special precautions (gloves, gowns, masks and other devices.) So, when the first Ebola cases arrive, the patients may not be overtly hemorrhaging. The bleeding often ocurs a little later in the disease. The staff treats them and could easily become infected themselves.

So the first wave of patients may sicken the healthcare workers who then become unable to care for the patients who follow in the subsequent waves. Though Ebola isn’t as infectious as some disease like influenza, it is easier to catch while in close proximity, as in a household, workplace or hospital setting. There is at least one report that shows that Ebola may be transmitted through respiratory secretions (large droplet-sized ones).

There is no specific treatment for Ebola

There is no specific treatment for Ebola. There is no antiviral medication that will stop it. There is no vaccine available for use to immunize people against Ebola. At best, Ebola patients need to be isolated to prevent the spread of virus, and healthcare workers need to use strict isolation techniques for the patients and to protect themselves. The rest of the treatment is symptomatic. Transfusion of blood and blood products to replace the blood lost by hemorrhage. Pain control, reduction of fever, rehydration and other support measures. Doctors in other countries have tried using immune globulin from horses containing anti-Ebola antibodies to treat Ebola. Others have used plasma from patients who have recovered from Ebola to treat current patients. These are controversial treatments, at best.

The majority of cases have been in Africa. But with international jet travel, the spread of many diseases is much easier than it would be otherwise. Incubation of Ebola (roughly the time from infection till the disease manifests itself) is about 1- 2 weeks. So, a visitor could be infected in Africa and return home a few days later, still not showing any symptoms of the disease. Then, a week later, become ill. The local doctors might suspect malaria or some other disease acquired in Africa, but, since Ebola is relatively uncommon, they probably wouldn’t think of a hemorrhagic fever virus until the patient started to actively bleed. So the disease could spread in its new location. It might take a few cases before anyone caught on that this was an Ebola outbreak. Even in areas with more advanced medical treatment, we could still expect a fairly high number of deaths since treatment is supportive only.

In the villages in Africa where Ebola outbreaks occurred, it seems as if getting the patients into isolation, alerting and protecting healthcare workers, getting the inhabitants to avoid the fruit bat reservoir, actively looking for people who might be ill and using some other methods, helped bring an end to the outbreaks.

Having an outbreak in Canada or the US isn’t far-fetched

Having an outbreak in Canada or the US isn’t far-fetched.

The Ebola virus, courtesy of Shutterstock

The Ebola virus, courtesy of Shutterstock

In fact, there was an Ebola outbreak in Reston, Virginia, close to Washington, DC, several years ago. Fortunately, it wasn’t Ebola Zaire. If it had been, there could have been an outbreak of Ebola in the US that could have caused deaths in the seat of government.

Fortunately, it was a strain of Ebola (later named “Reston”) that infected, sickened and killed non-human primates (in this case crab-eating macaques who were housed in a research facility in Reston.) Ebola Reston can infect humans, but it doesn’t cause illness in them. Several of the animal handlers seroconverted (developed antibodies against Ebola Reston), showing that they were exposed to the virus, but they remained healthy.

Macaca fuscata, or the Japanese Macaque (via Shutterstock)

Macaca fuscata, or the Japanese Macaque (via Shutterstock)

There is no clear-cut mechanism of how the virus spread from the macaques to the animal handlers. It may nave been through the handlers’ removing feces, coming in contact with infected animals’ secretions or some other mode. Ebola Reston was tracked back to the Philippines, home to the macaques. Studies in the Philippines have shown that some people there, who have been in contact with macaques and pigs, show antibodies to Ebola Reston but have never had a hemorrhagic fever themselves. In many of these people there is no definitive method that delineates the mechanism of exposure.

Of course, Ebola and the other hemorrhagic fevers are not the only serious viral diseases out there. There are a number of others that are almost as dangerous. With the ability of people to travel quickly, it has become easier to abet the spread of diseases. This is an ongoing problem that is being addressed by organizations like the World Health Organization and Centers for Disease Control. They are using education, surveillance and epidemiology to try to control new outbreaks.

For some interesting reading about previous Ebola outbreaks and the disease itself, these books are very good. “The Hot Zone” by Richard Preston, “Ebola” Dr. William Close.

Mark Thoma, MD, is a physician who did his residency in internal medicine. Mark has a long history of social activism, and was an early technogeek, and science junkie, after evolving through his nerd phase. Favorite quote: “The most exciting phrase to hear in science... is not 'Eureka!' (I found it!) but 'That's funny.'” - Isaac Asimov

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