Should you fret about bird flu? Experts weigh in

With bird flu marching across Asia and Europe and expected to reach the United States soon, scientists fear the H5N1 strain of the virus could evolve into a form that would spread more easily among humans. This has sparked fears, concerns and, most of all, questions.

MSNBC.com posed some frequently asked reader questions to top experts in the field. Our panel consisted of:

• Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, Bethesda, Md.
• Dr. Eric Toner, senior associate, The Center for Biosecurity, University of Pittsburgh Medical Center.
• Leslie A. Dierauf, center director at the U.S. Geological Survey’s National Wildlife Health Center, Madison, Wis.
• Lisa Caffery, epidemiology project coordinator, Genesis Medical Center, Davenport, Iowa.

Here’s what they had to say:

Why are medical experts so concerned about bird flu?

Fauci: Any influenza virus that is circulating with a potential to infect people — that is, a virus to which human society has never been exposed to before — poses a significant threat. It happened three times in the 20th century: with the infamous 1918 Spanish flu; in 1957 with a moderate event; and in 1968, which was a relatively minor pandemic. The 1918 one was a public health catastrophe, the likes of which we had never seen before.

There is a concern that sooner or later we will get another pandemic. The big uncertainty is when it’s going to happen and whether it’s going to be a 1918 version or it’s going to be a 1968 version.

There is a big spectrum of seriousness going from the horrendously serious to the relatively mild.

[Since 2003] we’ve seen the steady emergence of H5N1, a virus that is fundamentally a bird flu. It has killed tens of millions of birds and required the culling of millions of birds. It has evolved in such a way that, in very rare instances, it has jumped from a chicken to a human. It is highly virulent in humans, killing about 50 percent of the people it has infected.

The concern of medical experts is that the virus has the ability to evolve, to mutate and to exchange genes with other human viruses.

If we don’t get this under control in chickens and more people get exposed, we’re giving the virus the opportunity to evolve in a situation where it might — and this is a big if, because it isn’t inevitable that this will happen — evolve the capability in going from human to human.

Sabah Arar / AFP - Getty Images file You can't catch the bird flu by kissing someone. But you might from kissing an infected bird. Here, an Iraqi feeds his pigeon from his mouth in Baghdad, where birds have tested positive for the H5N1 strain.

If it does, then we could have a very serious situation. So, medical experts and public health officials need to prepare for the worst-case scenario.

That doesn’t mean the general public should assume that the worst case could occur. There is a big difference there.

What are the chances the H5N1 virus will emerge in pandemic form and begin spreading from person to person?

Fauci: You can’t put a quantitative number on what the chance is that this H5N1 is going to be a catastrophe. The complexity of things for this to happen is multifaceted and very complex. [A pandemic] is not necessarily going to be caused by the H5N1 virus. H5N1 may not, in fact, go anywhere and just dead-end itself.

The H5N1 virus has been spreading from Asia into Europe and Africa via migratory birds. How is it expected to reach the U.S.?

Dierauf: There are three main ways in which scientists believe avian influenza will arrive in North America. One, by commercial transport — egg products, illegal and legally (imported) birds, or smuggled meat. The second is on the wings of migratory birds. Those would be birds that come from Asia and intermingle with birds from Alaska. The third way would be people — the arrival of someone who is ill.

Ho / Reuters The H5NI virus as seen through a transmission electron micrograph with a magnification of 150,000 times.

Toner: It will probably come to this country on an airplane with someone who is sick or incubating the virus. But we’re not going to be able to stop the virus by screening people at airports. We know with SARS it was completely ineffective. There is no way to detect people who are incubating the disease.

What types of wild birds should we worry about?

Dierauf: H5N1 has been found in up to 80 species of birds. The ones we worry about most are the migratory birds that move long distances. If there is a pigeon or an urban goose that stays around all winter long, those are not the animals I worry about. It’s the birds that fly long distances.

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