Ebola outbreak: What you need to know

Medical personnel inside a clinic taking care of Ebola patients in the Kenema District on the outskirts of Kenema, Sierra Leone, on Sunday, July 27, 2014. (AP / Youssouf Bah)

The outbreak of Ebola in Guinea, Liberia and Sierra Leone in West Africa is now the largest such outbreak ever. By the end of July, the disease had infected more than 1,200 people and killed more than 670.

As health authorities race to stop this latest outbreak of the highly fatal disease, here’s what you need to know.

Where does the virus come from?

Ebola is caused by a virus that was first identified in 1976 during two simultaneous outbreaks in Sudan and in the Democratic Republic of Congo. Since then, there have been several sporadic outbreaks, primarily in villages in Central and West Africa near tropical rainforests.

Fruit bats are considered to be the natural hosts of the virus. Chimpanzees, gorillas, monkeys, forest antelope, and porcupines have also been infected with Ebola.

How does Ebola spread?

While highly fatal, Ebola is not considered highly contagious. The virus spreads from animals to humans through contact with the blood or organs of an infected animal. It can then spread person-to-person only from direct contact, through broken skin or mucous membranes, with the blood or bodily fluids of infected people.

The virus has also spread during burial services, when mourners observing tradition have cleaned the bodies of Ebola victims and been exposed to infected bodily fluids in the process.

It typically takes between 2 and 21 days from the time of infection until the onset of symptoms.

What happens to those infected?

Ebola is a viral hemorrhagic fever, so it causes intense fever as well as internal and external bleeding in most patients.

Early symptoms include a sudden onset of fever, intense weakness, muscle pain and headache. Those symptoms are followed by vomiting, diarrhea, rash. The most dangerous and frightening symptom is the heavy external bleeding from the nose and ears, as well as the internal bleeding, which can lead to shock, organ failure, and eventually, death.

Because the early symptoms of the illness are similar to the symptoms of many other illnesses, it can be difficult to identify the disease in its early stages. But patients who have not begun showing symptoms are not contagious.

Can it be treated?

In some outbreaks, up to 90 per cent of those infected with Ebola have died. The current outbreak is estimated to have a fatality rate of approximately 60 per cent, in part because many patients have benefitted from early treatment.

There are currently no vaccines available to prevent the disease, nor any specific treatments to treat it. Ebola severely dehydrates patients, so the most important treatment is intravenous rehydration. Patients also require medication to reduce their fever, pain control medicine, and nutrition.

The earlier that patients receive treatment in hospital, the higher their chance of survival. Those who do survive Ebola are considered immune to the strain they contracted.

How do health workers avoid infection?

Health workers can avoid becoming ill with Ebola by wearing hospital gowns, gloves and masks during every exposure to infected patients, and then disposing of the equipment after each contact. Any medical equipment that comes in contact with the patient also requires sterilization afterward. Bleach can kill any traces of the virus in the patient's environment.

Has the virus ever spread to Canada?

There's never been a case of Ebola outside of Africa. The risk to Canadians remains very low, despite the ongoing outbreak in West Africa. The World Health Organization does not recommend any travel restrictions be applied to the countries affected by this current outbreak, although Liberia has closed its borders to avoid further spread.

Earlier this year, doctors feared a Saskatchewan man may have contracted the virus after becoming sick following a trip to Liberia. The Public Health Agency of Canada later announced the man tested negative for Ebola.

For those Canadians travelling to areas affected by the latest outbreak, the Public Health Agency of Canada recommends that travellers see a doctor if they develop any symptoms during travel or within three weeks of their return.