The Alberta woman who died of H5N1 bird flu was in her 20s and a health-care worker at Red Deer Hospital.

More details emerged Thursday about the isolated, fatal case of H5N1, or avian influenza, that health officials announced yesterday. It was the first reported death from avian flu in North America. 

The infected woman, an Alberta resident who recently travelled to Beijing, China, died Jan. 3.

The World Health Organization is supporting the work of investigators in Canada and China who are trying to piece together how and where she was exposed to the virus.

Dr. Wenqing Zhang, head of the WHO's global influenza program, said Thursday the organization wants to get the big picture of the case.

 Zhang told CBC News from Geneva that two main questions need to be answered about the woman's death in Alberta: 

  • Where did she visit?
  • How did the exposure happen?

"At the moment, we know that the woman didn't visit a poultry farm or a poultry market, but that does not necessarily mean [that] exposure was excluded," Zhang said.

The woman was in her 20s and was a health-care worker at Red Deer Regional Hospital.

A second focus for the WHO is on close contacts, Zhang said. The goal is to understand whether any human-to-human transmission occurred.

Dr. Michael Gardam, an infectious disease consultant with Toronto's University Health Network who's not with the WHO, says it's "odd" for humans to get infected with H5N1 from a non-poultry source.

"Almost all of the cases that we've heard about going back to the 1990s, there's been direct contact with poultry," said Gardam. "So if this person hasn't visited farms and hasn't been around birds, that's very odd. I imagine they'll be doing a lot of sleuthing in China to figure out what happened."

China Bird Flu

Almost all H5N1 cases so far involved direct contact with poultry but that doesn't seem to be the case so far for Alberta's. ( Associated Press)

There's no evidence H5N1 can spread easily between people. When it has, there has been sustained contact, such as between patients and family members, or patients and health-care workers.

The window for any further transmission between people is closing, since normally people would get sick with symptoms two to eight days after exposure to the virus, Zhang said. The woman first showed symptoms of the flu on a Dec. 27 flight.

Part of the investigation involves interviewing people in Beijing and retracing their steps," said Andrew Potter, a microbiologist and director of the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Saskatoon.

"If you were to ask me what was I doing three, four weeks ago, I would have a very tough time telling you and I'm alive," Potter said in an interview. "Trying to trace it for somebody who is deceased is a very difficult procedure. The fact that it was in another country makes it even more so."

The patient's health, immunity, interactions with chickens, migratory birds or their droppings are also part of the equation for investigators, Potter said. Another is whether tests show if the patients' relatives who did not get sick mounted an immune response against H5N1.

The H5N1 virus is on WHO's radar as its experts look for any potential signs its gaining the ability to spread rapidly between people.