With the Ebola epidemic showing no signs of slowing in West Africa, it's likely just "a matter of time" before a case is diagnosed in Canada, says an expert on tracking infectious diseases.

Robert Smith, a professor of mathematics at the University of Ottawa and an expert at tracking diseases, says that, based on what we know about how infectious diseases spread, it may well be inevitable that the disease will arrive in Canada. Global travel is commonplace these days, he says, and that facilitates the spread of diseases.

"These diseases pop up. I think it's just a matter of time," Smith told CTV News Channel Thursday from Ottawa.

It's hard to predict exactly when the disease will arrive, "but the idea that it is not going to arrive has a very, very, very low probability," Smith says.

Dr. Kamran Khan, who studies the spread of infectious diseases by analyzing international air travel patterns, also says the risk of Canada receiving an imported case of Ebola is low. That's because Canada sees few travellers from Liberia, Sierra Leone and Guinea -- the countries most affected in this outbreak. Only 1.5 per cent of travellers to Canada every year come from these countries.

Still, the longer the epidemic goes on and the longer it remains out of control, the more the risk increases.

The Laboratory for the Modeling of Biological and Socio-Technical Systems (MoBS) at Northeastern University in Boston has been publishing and updating its predictions for how the disease may spread. It currently lists the U.S., France, and the United Kingdom as the countries outside Africa with the highest probability of receiving an imported case, in part because they are home to busy travel hubs.

MoBS research associate Marcelo Ferreira da Costa Gomes says the probability that a case will arrive in Canada by the end of the month is between one and five per cent.

Quarantine officers from the Public Health Agency of Canada are now working at six Canadian airports to screen travellers from countries affected by the Ebola outbreak.

These measures are likely only to delay the arrival of Ebola to Canada, Smith says, because the illness can incubate for as long as 21 days, allowing an infection to hide in unsuspecting travelers.

"That's frankly what we saw with the patient who slipped through into the U.S. He arrived in the country feeling perfectly well; those screening measures wouldn't have stopped that," he said.