The World Health Organization has begun its detective work into an H5N1 bird flu death in Alberta, to determine how and where the person 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?

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."

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.

The investigation involves interviewing people in Beijing and retracing their steps, said CBC health commentator and physician assistant Maureen Taylor.

"If they can't find a bird source, then what's going on with this virus?" Taylor asked. "There were companions of this victim on the plane. Were they with them in Beijing? What was brought into the home as far as eating? Were there birds brought in?"

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.
 

Also on HuffPost:

Loading Slideshow...
  • Myth: The Flu Shot Can Give You The Flu

    <strong>Fact:</strong> This myth just will not die. So let's clear this up: You <em>cannot</em> get the flu from your flu shot. Why? That vaccine is made from a dead or inactive virus that can no longer spread its fever-spiking properties. <a href="http://www.everydayhealth.com/cs-cold-flu-pictures-myths/colds-and-flu-whats-true.aspx#/slide-4">In rare cases, a person may experience a reaction to the shot</a> that includes a low-grade fever, but these reactions are not <em>The Flu</em>, Everyday Health reported. Note: Even though the flu shot cannot cause the flu, there are a number of other <a href="http://www.everydayhealth.com/cold-and-flu/flu-vaccines.aspx">reasons not to get the vaccine</a>, including for some people with an allergy to eggs or a history of Guillain-Barre Syndrome.

  • Myth: If You've Already Had Your Shot, You Are Guaranteed To Be Flu-Free

    <strong>Fact:</strong> Unfortunately, even after slapping a bandage on that injection site, you <a href="http://www.cdc.gov/flu/about/qa/vaccineeffect.htm">may only be about 60 percent protected</a>, according to the CDC. That means, yes, you <a href="http://www.npr.org/blogs/health/2013/01/08/168814935/can-you-get-a-flu-shot-and-still-get-the-flu">can still get the flu after your shot</a>. Some people may be exposed to the flu in the two weeks it takes for the vaccine to take effect, reports NPR. Others might be exposed to a strain not covered in the vaccine, which is made each year <a href="http://www.flu.gov/prevention-vaccination/vaccination/index.html">based on the viruses experts predict will be the most common</a>, according to Flu.gov. (This year's batch seems to have been matched well to what is actually going around, NPR reports.)

  • Myth: Antibiotics Can Fight The Flu

    <strong>Fact:</strong> Plain and simply, antibiotics fight <em>bacteria</em>, not viruses. The flu -- and colds, for that matter -- are caused by viruses. In fact, <a href="http://www.fda.gov/Drugs/ResourcesForYou/ucm078494.htm">antibiotics kill off the "good" bacteria</a> that help to fight off infections, so that viral flu may only get <em>worse</em>.

  • Myth: The Stomach Flu Is A Type Of Influenza

    <strong>Fact:</strong> Nausea, vomiting or diarrhea, while often dubbed the "stomach flu," are <a href="http://www.flu.gov/about_the_flu/seasonal/">not typically symptoms of seasonal influenza</a>, which, first and foremost, is a respiratory disease, according to Flu.gov. The flu can sometimes cause these issues, but they won't usually be the <em>main</em> symptoms -- and are more common signs of seasonal flu in children than adults.

  • Myth: If You're Young And Healthy, You Don't Need The Shot

    <strong>Fact:</strong> Younger, healthy adults aren't among the <a href="http://www.cdc.gov/flu/about/qa/flushot.htm#high-risk">people the CDC urges most strongly to get vaccinated</a>, like pregnant women, people over 65 and those with certain chronic medical conditions. The young and healthy will more often than not recover just fine from the flu, with or without the shot. But protecting yourself even if you don't think you need protecting can actually be an act of good. The <a href="http://healthland.time.com/2011/10/13/no-excuses-a-brief-guide-to-the-flu-shot/">more people are vaccinated, the fewer cases of flu we all pass around</a>, which in turn offers greater protection to those at-risk groups.

  • Myth: You Can Get The Flu From Being In The Cold Without A Coat (Or With Wet Hair)

    <strong>Fact:</strong> Mom or Grandma probably told you this one at some point, and while you might not feel so cozy if you head out the door straight from the shower, doing so doesn't exactly condemn you to bed. <a href="http://www.health.harvard.edu/flu-resource-center/10-flu-myths.htm">The <em>only</em> way to catch the flu is to come into contact with the virus</a> that causes it. That might happen <em>while</em> you are outside in the cold, and flu season does certainly happen during cold weather, but it's not because you're cold that you catch the bug.

  • Myth: There's No Treatment For The Flu

    <strong>Fact:</strong> It's not antibiotics that cure-seekers should be looking for. While the two antiviral drugs available to fight the flu aren't a quick fix, they <em>can</em> <a href="http://www.webmd.com/cold-and-flu/features/top-13-flu-myths?page=2">reduce the length of your bout of the flu and make you less contagious</a> to others, according to WebMD. This year's earlier-than-usual flu season has already led to <a href="http://www.huffingtonpost.com/2013/01/10/flu-vaccine-shortage-tamiflu-_n_2448519.html">shortages of one of the drugs, Tamiflu</a>, in the children's liquid formulation, according to the medication's manufacturers. However, a number of experts in countries around the world have questioned Tamiflu's efficacy in fighting the flu, and some have even <a href="http://www.huffingtonpost.com/2012/11/12/tamiflu-evidence-british-medical-journal-cochrane_n_2117287.html">suggested a boycott until further data is published</a>.