Bird Flu Woes: Flying This Way?
Experts discuss the potential impact of bird flu that could arrive in the U.S. via wild birds.
As soon as next summer, the wings of wild birds may carry Asia's deadly bird flu to America.
What would it mean? Like so much about bird flu, it's not entirely clear.
It certainly wouldn't be good news. But it just as certainly won't mean that a deadly human epidemic is imminent, says Christopher Brand, PhD.
Brand, charged with monitoring U.S. wild birds for signs of bird flu, is research branch chief at the USGS (U.S. Geological Survey) National Wildlife Health Center in Madison, Wis.
"It is certainly a possibility that we will see highly pathogenic avian influenza in wild birds in the U.S.," Brand tells WebMD. "We will learn more as we see what happens to this virus over the course of the winter. But so far, in Asia, the human cases have been in people who have had intimate contact with domestic fowl. We don't know of any cases where wild fowl gave it to a human."
Bird Flu Evolution
U.S. and world health authorities are very worried about the possibility that the bird flu sweeping Asia will learn to spread among humans. That would trigger a worldwide flu epidemic -- a pandemic, as health experts call it.
Flu pandemics have occurred throughout history. Some were very bad. Some weren't. The current bird flu looks particularly nasty, as it's killed more than half the people known to have caught it from poultry. And it's picking up some scary powers as it evolves:
- The H5N1 bird flu virus can't be eradicated. It's found a niche among the wild and domestic ducks of Asia. These ducks don't get sick but do excrete huge amounts of the virus into the water supply.
- H5N1 bird flu has learned to survive under a wide range of environmental conditions. It survives in raw chicken (although thorough cooking kills it) and bird droppings.
- H5N1 bird flu is becoming more and more lethal to poultry.
- H5N1 bird flu has increased the number of animal species it can infect and kill, including rodents, domestic cats, and humans.
Bird Flu's Next Move
Scientists -- who think in the very long term -- see an eventual flu pandemic as inevitable. They hedge their bets by saying it might not be the deadly Asian H5N1 that causes the next one. Even so, this scary virus already seems ready to jump to humans. "Seems" is the key word here.
We knew about previous flu pandemic only when people started getting sick. This time, for the first time, scientists are able to watch the virus evolve. What they are seeing is cause for concern -- but there's no way to tell how likely it is that these concerns will become reality. This is the first time anybody has seen these things, says Stephen Morse, PhD, director of the Center for Public Health Preparedness at Columbia University, New York.
"It is a little like a clock striking 13 -- it is a whole new thing, and we don't know what to expect," Morse tells WebMD. "What flu strain is going to be the next pandemic and when? Many people come to grief trying to predict this. It does say something about our science. We have a limited handle on what achieving human-to-human transmission involves. It is not something we can predict very well."