As west Africa Ebola outbreak reaches historic proportions - where does it come from, how is it spread and why is it so deadly?

Tuesday, July 29, 2014, 3:07 PM - The deadly outbreak of the Ebola virus in west Africa is now considered the worst in history, with at least 672 deaths so far since February, among nearly 1,200 reported infections in the nations of Sierra Leone, Liberia, Guinea and now Nigeria. With health officials attempt to contain the spread of the disease, it's all coming down to education, so here are the facts on this deadly virus.

1) It is one of the deadliest viruses known

The death toll from this outbreak currently sits at around 56 per cent of the total number of people infected so far. However, as this specific strain of ebolavirus - Ebola virus (or Zaire ebolavirus), first identified in Zaire in 1976 - is known to kill up to 90 per cent of victims in any particular outbreak, the total death toll could end up being much higher. The four other known strains are generally less deadly: Sudan ebolavirus, which was also discovered in 1976, claims between 50-70 per cent of those infected, Bundibugyo ebolavirus, discovered in western Uganda in 2007, has a fatality rate of between 25-50 per cent, Taï Forest ebolavirus was first seen in Côte d'Ivoire (The Ivory Coast) in 1994, with only one known infection (the person recovered), and Reston ebolavirus, which does infect other non-human primates, but is not known to infect humans. 

According to the CDC, doctors and researchers still don't know exactly why the virus is so deadly, but recent research has shown that Ebola has the scary ability to prevent our immune system from turning its full fighting strength against the virus. With only a limited response arrayed against it, the virus can completely overrun the body.

2) Its symptoms are especially nasty

When it comes to viral infections, you can't get much worse than Ebola. Once infected, a person develops symptoms in as little as two days, but it could take up to three weeks. Weakness, headaches, muscle and joint pain, stomach pain, vomiting, diarrhea, and extremely high fever are the most common symptoms that develop, possibly along with sore throat, rash, red eyes, coughing, and difficulty breathing or swallowing. As the virus continues to invade the body, it causes blood clots, which end up damaging major organs and causing massive internal bleeding (which is where the hemorrhagic in the name comes from).

3) It spreads very easily, but only through direct contact

Ebola is highly infectious, but so far it can only be contracted through either direct contact with the infected - either the original animal (most likely fruit bats) or any infected primate or human. The blood, saliva, and any other fluid or secretion that comes out of the infected's body is expected to contain the virus, so contact with any of these can result in infection. It can also be spread through the use of improperly cleaned medical instruments. So, despite the extremely deadly nature of the virus, it is typically easy to contain, as health officials isolate the victims for treatment, educate the local population on how to avoid infection, and increase sanitation measure in treatment centres and hospitals. One issue complicating the situation in western Africa is that cultural practices are trumping advice from medical personnel. The traditional method of preparing the deceased for burial in the region is a highly-respectful ritual involving the person's family hand washing the body. However, as this brings those people into direct contact with bodily fluids that still contain the virus, this results in further infections. Other issues are that, apparently, some people living in the affected region don't even believe that the virus exists, and others believe that faith healers can do more good for their loved ones than the doctors and health officials trying to limit the spread.

4) There is no vaccination or cure for Ebola

Although efforts are ongoing to develop a vaccine for Ebola, once a person has become infected, there's little that can be done for them, except to help with the symptoms of the illness. Patients are given intravenous fluids, they are provided with supportive care, but it is up to their body to deal with the infection from there. If they can recover, it is often a full and complete recovery, as what happened with Abdullah D., a husband, and father of twins, from Guinea (click here for his story). Strides are being made by the medical community to develop a vaccine, with some of the latest results including the development of antibodies in primates. However, we may be some ways away from having something that is useful for humans.

5) This outbreak is spreading faster and farther than any other in the past

At this time, the virus has claimed 672 lives, in 4 different African countries. It began in Guinea, where 319 people have died since February, then spread to bordering Sierra Leone (224 deaths) and Liberia (129 deaths) by March, and one of the latest deaths was in Nigeria. This is far and above previous outbreaks, which have been limited to one country and a maximum of 280 deaths (in the first Zaire outbreak in 1976). With this latest case, it was a Liberian government worker who recently flew into Nigeria, and health officials are watching closely for anyone else who shows signs of infection there, as well as in Togo, where the person's plane landed on the way to Nigeria.

This latest case is revealing one of the biggest worries about this outbreak. Although an airborne strain of Ebola would be a nightmare, it isn't required to turn an epidemic into a pandemic. With symptoms developing up to three weeks after infection, that is plenty of time for the infected person to board an airplane and fly anywhere in the world, interact with numerous people, and spread the virus to everyone they come into contact with. Governments and health officials are being as cautious as they can, with Liberia recently closing down all but three border crossings into Guinea and Sierra Leone, and opening up testing stations in the country's airports. Identifying all infected people may be difficult, though, given the delayed onset of symptoms, but this does decrease the chances of it spreading.

What are the chances of this epidemic spreading to other continents? 

"The chance of Ebola spreading out of West Africa is very, very low," Kamran M. Khan, an infectious disease specialist with St. Michael's Hospital in Toronto told NPR in June. "But if it did spread, Paris is probably the first city on the list."

"The volume of travel in the Conakry airport is low," Khan added in the interview. "Most of the flights are local. But 10 per cent of the traffic goes to Paris." Since the city is closer to northwest Africa than most other major international cities, it would make it the easiest for the virus to spread to, as the person would become ill after they arrived, and potentially spread the virus to others there. As for the virus being spread to other people en route, this is fairly unlikely. For an airborne virus, it would be easy, but we tend to avoid contact with people, even in the close-quarters of an airliner cabin. Coming into contact with an infected person's bodily fluids, especially if they're showing no signs of sickness, would be very rare, and anyone who was showing signs of infection would likely be pulled out of the queue before boarding.

So, although concerns are certainly there, and the situation in west Africa is very serious right now, fortunately the chances of this becoming a world-wide problem are quite low.