Last reviewed and revised on August 9, 2012
By Anthony L. Komaroff, M.D.
Brigham and Women's Hospital
For more than a decade, public health officials and researchers have planned for the possibility of an epidemic of bird flu. Everyone hopes that such an outbreak never occurs. Meanwhile, thousands of people die of regular flu each year. We talked with Anthony L. Komaroff, M.D., about the possible threat of bird flu. Dr. Komaroff is a professor of medicine at Harvard Medical School.
What is bird flu?
Bird (avian) flu is a type of influenza virus that affects mainly birds. However, the world health community is concerned about one particular strain of bird flu virus, H5N1, that can sometimes spread to humans. As of January 2012, this virus has infected more than 600 people worldwide; over 300 have died. Fortunately, the virus currently is very hard to pass from animals to humans, and even harder to spread from humans to other humans.
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Bird flu received so much attention in 2005. Interest seems to have faded since then. What has changed?
Very little has changed, although there is less media coverage. Doctors remain very concerned about H5N1.
At the moment, this is a good news/bad news virus. The good news is that the virus has not developed the ability to spread easily from person to person, the way most flu viruses can. The bad news is that when humans are infected with the virus, they become extremely sick.
What people are worried about is the possibility that the H5N1 virus could change (mutate) in a way that makes it able to spread to and among humans. If this occurred, it could cause a worldwide epidemic (called a pandemic).
The situation is still a worldwide concern for governments and health organizations. However, now that more countries have become aware of the H5N1 virus and the possible dangers, more preparation has been put into place.
The website of the U.S. Centers for Disease Control and Prevention (CDC) offers the latest information on bird flu around the world. Most outbreaks continue to be in Asia, parts of Europe, Africa and the Near East. They are not expected to ease any time soon.
In nearly all cases, the virus has been transmitted from birds to humans. Usually, the person got sick because he or she handled an infected bird. Only a few cases involved a human catching the disease from another person.
Nevertheless, the CDC and the World Health Organization are taking the possibility of an epidemic of bird flu quite seriously.
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With flu season starting, how would you compare the current threat of regular influenza with bird flu?
Today, regular influenza caused by the influenza A and B viruses poses a much greater threat than bird flu, because it can be spread easily among people. Approximately 20,000 to 40,000 U.S. citizens most of them older and ill from other diseases die each year from influenza.
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Few people have close contact with birds, so what's the big worry?
There would be no significant concern if we knew that the bird flu virus would never change. Unfortunately, however, the genes of flu viruses mutate (change) easily. The H5N1 virus still could mutate into a new form that spreads easily between species and, more importantly, between humans.
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If the virus did mutate and could be transmitted from human to human, how could we control it?
Scientists are making progress in developing a safe vaccine against bird flu. The antiviral drugs oseltamivir (Tamiflu) and zanamivir (Relenza) may prevent bird flu, but we can't know how effective they are until and unless there is a pandemic of bird flu. Also, if too many people take Tamiflu or Relenza indiscriminately, the virus will almost surely become resistant to the medications.
If there ever was a pandemic of the H5N1 bird flu virus, extraordinary measures might be used to keep people from being in close contact with one another. Schools might be closed, and events and meetings involving groups of people could be canceled. Workplaces probably would get people to work from home if possible. Public transportation also would be disrupted, if not stopped altogether, during an epidemic.
The elderly and others who need assistance would get the most attention from officials. Anyone who might need extra help should plan accordingly.
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How is the H5N1 bird flu virus different from the H1N1 swine flu virus that caused such concern in 2009?
The H1N1 "swine flu" virus is a virus that mutated in a way that made it suddenly easy for humans to catch, and to spread to other humans. It changed in the way that scientists worry the H5N1 bird flu virus might one day. The H1N1 virus did kill some people, and caused more severe illness in young people and in pregnant women than do the regular annual flu viruses. However, it caused much less severe illness in the people who are most vulnerable to becoming seriously ill when they catch the flu: people over age 50. So overall the H1N1 virus has not yet caused as much suffering as was feared at first.
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Is it true that scientists have changed the H5N1 bird flu virus to make it more contagious?
Laboratories in the U.S. and the Netherlands have been studying whether any particular mutations make the H5N1 virus more easily transmitted to and between humans. This research is conducted in extremely secure laboratories designed to prevent viruses from affecting the scientists, and from escaping into the outside world. The laboratories have identified changes in the H5N1 virus that allow it to easily infect an animal, a ferret (a small furry mammal related to polecats). Influenza viruses generally affect ferrets in a similar manner to humans, which is why scientific studies use ferrets to learn things about human flu.
Why would scientists study this? To learn ways to "outwit" such a virus, it a mutant form of H5N1 should develop naturally, somewhere in the world. For example, such research might spot at a very early stage the natural development of such a virus, and allow a quarantine that kept the virus from spreading. As another example, such research might identify new treatments for such a virus, or vaccines against such a virus. Those treatments and vaccines might then be ready if an epidemic of such a virus ever developed.
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Anthony L. Komaroff, M.D. is the Simcox-Clifford-Higby professor of medicine and editor-in-chief of Harvard Health Publications at Harvard Medical School. Dr. Komaroff also is senior physician and was formerly director of the Division of General Medicine at Brigham and Women's Hospital. Dr. Komaroff has served on various advisory committees to the federal government, and is an elected Fellow of the American Association for the Advancement of Science.