An Alberta woman who died from H5N1 bird flu was in her late 20s, according to the World Health Organization, which has begun investigating the case and is awaiting a sample of the virus for further study.

Federal officials announced the death Wednesday, saying the woman was the first to die of this kind of flu in North America.

As a precaution, those who travelled on the same flight as the woman will be contacted and informed of her death, and assured they are at low risk of infection.

The woman flew from Beijing to Vancouver on Dec. 27 aboard Air Canada flight 030. She then boarded Air Canada flight 244 to Edmonton.

Anyone who travelled on either of those flights can call health officials at 1-866 225-0709.

Dr. Nikki Shindo, a medical officer with the WHO, said because this is the first H5N1 case in North America, “this is substantial.” Shindo told CTV News that the agency is awaiting further information about the case, and “soon we will receive the virus at a WHO collaborating centre.”

WHO officials are in close contact with both Canadian and Chinese public health officials, and are “closely monitoring the investigation taking place in China,” she said.

Questions that need answering include when and how was this woman exposed to the virus and what were her activities before she fell ill?

Officials will also want to know about the woman’s main symptoms, how the disease progressed, the treatment she received and if there were any atypical characteristics about the virus, Shindo said.

The unidentified woman had recently returned from spending several weeks in China, mainly in the capital of Beijing, officials told reporters Wednesday. She began to feel ill on her flight home on Dec. 27.

Public health officials told CTV News the woman went to the hospital the following day with symptoms of headaches and malaise. But because her symptoms were common to the H1N1 virus, she was sent home. Alberta is currently facing a spike in seasonal flu cases.

The woman then returned to hospital on Jan. 1 with more severe symptoms.

Public health officials are assuring there is no need to panic over the news, saying the likelihood that she infected anyone else or that Canada will soon start seeing other similar cases is extremely low.

There are very few incidences of human-to-human transmission of H5N1, and is usually the result of “close, unprotected, prolonged contact with a symptomatic patient,” Shindo said.

Dr. Gregory Taylor, Canada’s deputy chief public health officer, told CTV’s Canada AM the woman’s condition quickly deteriorated a couple of days after she returned home.

“She became ill very, very quickly and ultimately died. This person died of an infection in the brain that was very severe,” he said.

“That’s very much in keeping with what happens with this particular virus. Of the people who get infected, 60 per cent die.”

While the woman’s death caught health officials in Canada by surprise, Taylor and other officials say there is nevertheless no cause for alarm.

They note that the H5N1 flu strain has been known to scientists for at least 15 years, and has become endemic in birds in China and elsewhere in Asia. It’s also been the subject of intense study during that time.

And what has been learned is that the majority of humans who have become infected with it had close contact with live birds, either on farms or in live animal markets.

What’s also been learned is that the virus doesn’t infect humans easily, given that thousands of people have likely been exposed to the virus over the last decade or more.

“In the entire world over the last 10 years, there have been fewer than 650 human cases,” Taylor noted.

Infectious diseases expert Dr. Neil Rau says he’s not concerned that bird flu illnesses will now be regularly diagnosed in Canada.

“It took 15 years for someone who was a traveller from North America to go to one of those places (where the virus is circulating among birds), acquire it and then fly home,” he said. “So in my view, I’m reassured that it has taken so long for this to occur. It shows you the rarity of this kind of event.”

Rau and Taylor also say they are not concerned that others in Canada will become infected, as person-to-person transmission of avian flu is “extremely rare.”

In the handful of cases that have occurred, the virus spread only to family members who had close and extended contact with infected patients. What’s more, the transmission ended there, with the secondary infections not going on to infect others.

“The truth is this virus still does not transmit easily in humans,” says Rau.

Nevertheless, the woman’s family members are being monitored as a precaution and have been offered Tamiflu, an antiviral medication used for severe flu treatment that can also help prevent infection. Officials say the woman’s family members are not showing any signs of illness.

Rau says it’s especially unlikely this woman infected others, given that she was not sneezing and coughing -- which are the most common ways to spread flu viruses.

“She did not have the cough-symptoms-and-the-worsening-pneumonia story. So just given her type of symptoms, the risk of transmission is extremely low, never mind that the virus itself doesn’t transmit easily,” he said.

Taylor said health officials were “very confident that the risk to anyone sitting beside this person was very, very low.”