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Bird flu a worry in Asia

Dr. Drew Werner

EAGLE COUNTY – Kids are germ factories, it often seems, catching and passing on everything they come into contact with. The factory analogy is true only in that they so readily produce and distribute – freely, I might add – any infection they have. In truth, our young children suffer so many infections because their immune systems have not built up the resistance to infection that only exposure or vaccination may bring.Dear Doc: I have heard a lot about the bird flu. I received my flu shot this year. Am I safe from getting it, or should I stop eating chicken?- Trying to Stay Healthy in MinturnDear Healthy: I am glad you had a flu shot and I hope you keep eating your chicken, but I think a little explaining is in order about our immune systems and the flu. Our immune system is an amazing thing. Like an elephant, it never forgets. Once exposed to a virus or bacteria, it remembers the invading organism and prepares an immunologic response to quickly and efficiently ward off the offending infection. Should we be exposed to the same infection again, we have “immunity” and are prepared to fight off the infection before we become sick. The key word is exposure, however. That is why children get sick so easily. Their immune systems have little exposure to viruses and bacteria and so have fewer built in defenses. As exposure occurs over time, our immune memories become more and more advanced and we become better able to overcome infections.At the same time, the viruses and bacteria are fighting back. There may be many different strains of bacteria, each resistant to a previously effective treatment or immune response. Viruses just mutate. They change enough to fool our immune systems into no longer recognizing them. The classic example is the flu. Each year it changes enough that our prior immunity is rendered ineffective.It is a good thing that we have developed immunity over time and can fight off many infections with little or no help. If an infection comes along, however, that people have never been exposed to, it could be pandemic. That is where avian, or bird, flu fits in. There are many infections called the flu. It actually refers to a class of viruses that infect people and animals. While we have talked about Influenza A and B that are causing so much illness now in our community, avian flu is different and a new illness to humans.Previously thought to infect only chickens, avian flu has at least 15 different subtypes. It has been found throughout the world, commonly in the Far East. In 1987 a particularly aggressive strain called H5N1 jumped to humans and caused six deaths in an outbreak in Hong Kong. In a successful effort to contain the infection, 1.5 million chickens were killed to prevent its spread. Until September of 2004, human infection was only found in those who had close exposure to chickens from which they acquired the illness. Still a concern, the Asian bird flu, as it is now called, killed 70 percent of the humans it infected. Then, in September of 2004, the unthinkable happened. The Asian bird flu was transmitted directly from one person to another. While the illness acquired from person to person contact was much milder, the worry is that it could combine with human influenza and produce a more deadly and far more contagious strain. That has not yet happened, so human-to-human transmission has been rare.World Health Organization leaders fear that a new, highly lethal strain of bird influenza that had combined with the human flu could cause a pandemic like the worldwide 1918-19 human influenza outbreak. During the 24 weeks of that 1918 flu season, between 50 million and 100 million people died across the world. It was the single greatest cause of human death ever recorded. In order to prepare for the risk of an Asian bird flu pandemic, the U.S. and Great Britain are developing vaccines that are nearing human testing. At the same time, anti-viral medications are being stockpiled just in case an outbreak occurs.Should you be worried? Definitely not. This virus is being intensely scrutinized. If an outbreak should occur, there would be plenty of warning. At the same time, there is no risk of infection from eating chickens, so enjoy that low-fat food. To date, there have only been localized outbreaks in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand and Vietnam. Travelers visiting those countries who develop a febrile illness should contact their physician.For now, wash your hands and be glad for the resources we have here in our country looking out for us all. Most of all, spend your energy wisely, enjoy our last weeks of snow and look forward to a beautiful spring.Dr. Drew Werner of the Eagle Valley Medical Center writes a weekly column for the Daily. He encourages health questions. Write him by e-mail to editor@vaildaily.com or c/o Editor, Vail Daily, P.O. Box 81, Vail, 81658.Vail, Colorado


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