Public health officials say Canadians have little to fear about Ebola ever spreading widely in Canada, but the case of a man in Dallas being diagnosed with the deadly hemorrhagic fever has raised a lot of worries.

Was he contagious to all those who travelled with him? Could he have left traces of the virus in the plane, the airport, or other places he travelled? What if others arrive like him and move around a community for days before being diagnosed?

These are all valid worries, but it’s important to remember that Ebola virus isn’t new. It’s been studied for years and scientists are already quite familiar with how it spreads. Here’s a look at some of those questions and their answers.

How long does the Ebola virus live on surfaces?

We’ve been hearing for months that Ebola virus has been shown to survive for days on surfaces, but it’s important to consider a few things.

First off, viruses do not survive long on porous surfaces, such as fabrics for example. They can live longer on hard surfaces, such as metal and glass. As well, there have been lab studies showing that dried samples of Ebola virus can survive for days; but other studies have found the virus doesn’t survive more than a few hours outside of a host.

It’s important to note that in the tests where the virus lived for days, they were kept in the dark, at low temperatures, around 4 degrees Celsius, which helped the viruses survive.

In real life, the Ebola virus is sensitive to light, heat and low humidity, so it’s less likely to live long in environments such as brightly lit airplanes or hospital waiting rooms, both of which are scrubbed down regularly.

How easy is it to kill the virus from surfaces?

Relatively easy. In the Ebola-affected countries, health teams are using bleach to disinfect surfaces and bed sheets. But good hospital-grade disinfectants will kill off the virus as well, as will alcohol-based and acetic-acid based cleaners.

Could someone become infected by touching things the infected person has touched?

While the possibility exists, the U.S. Centers for Disease Control says there is “no epidemiologic evidence of Ebola virus transmission via either the environment or (surfaces) that could become contaminated during patient care.”

Infectious diseases expert Dr. Neil Rau say says it’s unlikely someone in Canada could become infected by touching a contaminated surface for a few reasons.

For one, only those who are actively ill are shedding large amounts of the virus. As well, the virus has to more than just touch your hand; it has to enter broken skin, or mucous membranes, such as the eyes, mouth, nose and eyes. The virus would have to transfer from the hand of a highly ill patient, survive on a doorknob, then move to the hand of another person, then to their mucous membranes.

While it’s all theoretically possible, as Dr. Rau says, “lots of low probability events would need to come together to transmit by these means.”

The possibility increases for those working in health care in affected countries, of course, since they may be surrounded by highly ill patients. But that’s why they are taking protective measures such as wearing gowns, gloves and masks.

What if I shook hands with someone who was in the early stages of illness?

In the early stages of the illness, when patients develop a fever, a patient is not shedding as much virus as they will in later stages of illness. But by those later stages, the person is very ill and almost certainly bed-ridden with fever, intense fatigue, vomiting and diarrhea, and not shaking hands.

While it’s impossible to know how every patient became infected, it’s safe to say that the vast majority came from people directly touching the fluids or the dead body of a patients who were actively ill. The patient in Dallas, for example, helped to carry the very ill daughter of his landlord to a clinic. She was turned away from the overcrowded clinic and carried home, where she later died.

What if the virus mutates and learns to become airborne?

If someone with Ebola sneezes or coughs and the saliva hits another’s eyes or nose, there is a risk of transmitting the infection, but this is not what is meant by an "airborne” transmission.

“Airborne” means the virus can live suspended in tiny droplets in the air, which Ebola cannot do.

It is theoretically possible that an RNA virus such as Ebola could mutate, and with each case of infection, that possibility increases slightly. But remember that HIV, also an RNA virus, has never mutated to change its mode of infection. And it’s infected more than 75 million people -- many more than have contracted Ebola.

In fact, it doesn’t appear that any human virus has ever changed its method of transmission, so while the possibility exists in theory, most infectious diseases experts feel assured it’s highly unlikely.