| By Maria Cheng December 11, 2006 9:21AM H5N1 -- the avian flu -- has primarily stalked Asia. This year, however, H5N1 crossed the continental divide, infecting people in Turkey, Iraq, Egypt, Djibouti, and Azerbaijan. But despite the deaths of 154 people, and hundreds of millions of birds worldwide dying and being slaughtered, the H5N1 virus still hasn't learned how to infect humans easily. Earlier this year, bird flu panic was in full swing: The French feared for their foie gras, the Swiss locked their chickens indoors, and Americans enlisted prison inmates in Alaska to help spot infected wild birds. With the feared H5N1 virus -- previously confined to Southeast Asia -- striking birds in places as diverse as Germany, Egypt, and Nigeria, it seemed inevitable that a flu pandemic would erupt. Then the virus went quiet. Except for a steady stream of human cases from Indonesia, the current bird flu epicenter, the past year's worries about a catastrophic global flu outbreak largely disappeared from the radar screen. What happened? Part of the explanation may be seasonal. Bird flu tends to be most active in the colder months, as the virus survives longer at low temperatures. "Many of us are holding our breaths to see what happens in the winter," said Dr. Malik Peiris, a microbiology professor at Hong Kong University. "H5N1 spread very rapidly last year," Peiris notes, "so the question is, was that a one-off incident?" Some experts suspect poultry vaccination has, paradoxically, complicated detection. Vaccination reduces the amount of virus circulating, but low levels of the virus may still be causing outbreaks -- without the obvious signs of dying birds. "It's now harder to spot what's happening with the flu in animals and humans," said Dr. Angus Nicoll, influenza director at the European Centre for Disease Prevention and Control. While the pandemic hasn't materialized, experts say it's too early to relax. "We have a visible risk in front of us," said Dr. Keiji Fukuda, coordinator of the World Health Organization's global influenza program. But although the virus could mutate into a pandemic strain, Fukuda points out that it might go the other direction instead, becoming less dangerous for humans. H5N1 has primarily stalked Asia. This year, however, it crossed the continental divide, infecting people in Turkey, Iraq, Egypt, Djibouti, and Azerbaijan. But despite the deaths of 154 people, and hundreds of millions of birds worldwide dying and being slaughtered, the virus still hasn't learned how to infect humans easily. Flu viruses constantly evolve, so the mere appearance of mutations isn't enough to raise alarm. The key is to identify which mutations are the most worrisome. "We don't really know how many changes this virus has got to make to adapt to humans, if it can at all," said Dr. Richard Webby, a bird flu expert at St. Jude Children's Research Hospital in Tennessee. The most obvious sign that a pandemic may be under way will almost certainly come from the field: a sudden spike in cases suggesting human-to-human transmission. the last pandemic struck in 1968 -- when bird flu combined with a human strain and went on to kill 1 million people worldwide. (continued...) http://www.sci-tech-today.com/story.xhtml?story_id=023000HIKLI1&page=2 |