Ebola outbreak: Here's what you need to know

CBC News is dedicating a special day of coverage to the Ebola crisison Tuesday. On radio, television and online, we'll explore the facts behind Ebola and answer questions. Be part of the conversation Tuesday by using #ebolafacts on social media or by joining our live chat on CBCNews.ca starting at8 p.m. ET.

International health authorities are trying to contain what is being called "the largest and most complex" outbreak of the deadly Ebola virus since its discovery.

• Read the latest information on the Ebolacrisis
• By the numbers: How bad is the Ebola outbreak?

Here is what you need to know about the disease and the ongoing outbreak, which the World Health Organization says has likely claimed nearly 4,500 lives.

What is Ebola?

Ebola its proper name is Ebola virus disease first appeared in two simultaneous outbreaks in 1976 in rural Sudan and rural Democratic Republic of Congo. The second location was near the Ebola River, hence the virus's namesake.

It's believed to be carried by certain species of fruit bats in Africa. They can spread Ebola to humans directly or indirectly through other animals.

How does Ebola spread?

People can acquire the virus from infected animals or humans.

Eating infected bushmeat or coming in close contact with bodily fluids of infected or deceased animals can transmit the virus.

Butmost cases in the current West Africa outbreak have come from human-to-human transmission, according to the World Health Organization. If a healthy individual's broken skin or mucous membranes comein contact with the bodily fluids of an infected individual or with an environment contaminated by an Ebola patient's bodily fluids, they can contract the virus.

"That means someone coughs in your face, you handle a body or you look after someone and don't have ideal infection-control methods. You get the virus on your hands, you touch your nose, your mouth," explainsDr. Jay Keystone, who works in the tropical diseases unit of Toronto General Hospital.

The virus can be spread through bodily fluids such as:

• blood
• stool
• urine
• saliva
• semen

Environmental hazards that could be infected with an Ebola patient's bodily fluids include:

• soiled clothing
• bed linen
• used needles

Once someone is infected, however, they can't spread the disease until the start showing symptoms, which generally appear between two to 21 days aftertransmission.

The disease is not airborne, meaning it cannot be transmitted simply by being in the same space as an infected individual.

What are the symptoms?

The virus attacks three types of cells: hepatocytes (functional cells of the liver), endothelial (which form the linings of the blood vesses) and phagocytes (absorb foreign particles).

• What are the symptoms of Ebola?

Symptoms start to appear in stages. First, a person can experience sudden fever fatigue, muscle pain, headache and sore throat, according to WHO. Next, a patient will demonstrate vomiting,diarrhea, rashand symptoms of impairedkidney and liver function. Some people will have internal and external bleeding at this point as well.

How is Ebola treated?

There is no known treatment or licensedvaccine, but doctors can treatEbola patients with some effectiveness and scientists have developed some experimental vaccines.

• 1st human trials of Canadian Ebola vaccine start in U.S.

Doctors caring for Ebola patients can provide rehydration and treat specific symptoms, which improves the chances of survival.

Infected patients should also be isolated to prevent further spreading the disease.

Can someone with the virus be cured?

Not everyone who contracts the Ebola virus dies. The WHO pegs the fatality rate during this outbreak at around 50 percent, while Dr. Keystone says it's a bit higher, at 60 per cent.

"It all depends on the quality of medical care," he explains."The better the care, the more likely you are to survive."

Previous Ebola outbreak fatality rates have ranged between 25-90 per cent, according to WHO.

Dr. Peter Piot, Ebola co-discoverer

10 years ago

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Ebola co-discoverer on the outbreak and the need to push through on vaccines

Where are there documented cases?

The current outbreak started in West Africa, with the first confirmed case in Guinea in December 2013, according tothe European Centres for Disease Control and Prevention.

Liberia, Sierra Leone and Guinea have beenparticularly hard hit by the ongoing outbreak. Liberia has been the hardest hit, with 4,279 cases reported and 2,458 deaths as of Oct. 15, according to WHO figures. Sierra Leone had 3,252 cases and 1,183 deaths and Guinea had 1,472 cases and 843 deaths.

WHO figures of total cases consist of "probable, confirmed and suspected" cases, as exact figures have been difficult to measure given the weak health infrastructure and limited resources in many affected areas.

The better the care, more likely you are to survive.-Dr. Jay Keystone, works at Toronto General Hospital's tropical diseases unit

Senegal had just one case and Nigeria 20, the WHO says.

Nigeria's rapid response is to thank for its contained outbreak. Officials quickly isolated their first confirmed case and determined who the individual had come in contact with,theCentersfor Disease Control and Prevention said.

At the end of September, a man in the United States was the first to be diagnosed in the U.S. with Ebola, the CDCconfirmed. Thomas Eric Duncan, who later died of Ebola,had travelled from Liberiato Dallas, Tex.

Since then, two nurses who were involved in his treatment have also been diagnosed with the disease. A nursing assistant in Spain who was involved in the treatment of an Ebola patient there also contracted the disease.

What's different about this Ebola outbreak?

The WHO calls this Ebola outbreak "the largest and most complex" since the discovery of the virus.

It's unique becausepeople in villages and major cities are being diagnosed, and almost all cases are from human-to-human transmission.

"First, there's a lot of cross-border travel. Whereas most other outbreaks have been isolated in the middle of virtually nowhere," says Dr. Keystone.

Keystone added that citizens in the affected countries didn't trust local governments and often hid infections. People often took bodies home, he said, and funeral norms required people to touch the body.

While information about Ebola may have been limitedin the early days of the outbreak, health officials and organizations working in affected West African nations have since puton a major push to inform people about the disease and how it's transmitted.

Body removal crews have been created to safely handle and dispose of bodies and temporary hospitals have been set up to properly treat people with the disease.

How likely is it to appear in Canada?

With the United States diagnosing its first case of Ebola, it's natural to be concerned that the virus may come to Canada.

"I want to reassure everyone that the risk to Canadians remains very low," said Dr. Gregory Taylor, Canada's chief public health officer, at a meeting of federal, provincial and territorial health ministers.

Canada's Health Minister Rona Ambrose agreed, saying that "Canada is very well prepared" for dealing with infectious diseases.

Can I still travel?

The Canadian government recommends that citizens avoid non-essential travel to Nigeria, Guinea, Sierra Leone and Liberia.

Butthe WHO says there's little risk for people travelling to West Africa on business or to visit family and friends.

"The most important thing is to try and stay away from people who are ill. You won't get Ebola unless the individual you're in contact with is sick," says Dr. Keystone.