How Bird Flu Works

A Global Flu Pandemic

Some people wonder whether scientists are overreacting to bird flu. After all, the virus has infected under 200 people, as compared to millions of birds. It also can't easily move from birds to people, and it's even less able to move from person to person. But public health officials have several concerns about avian flu:

  • It has an extremely high mortality rate and kills previously healthy young adults.
  • Since many wild, migrating birds carry it, controlling its spread is difficult.
  • There's no vaccine for the virus, which appears to be developing a resistance to the few drugs that can limit its severity. Scientists are also investigating whether use of amantadine - a drug intended for humans - in Chinese poultry may have caused additional resistance.

Right now, avian flu H5N1 is most threatening to birds, especially in Asia. The biggest threat to human health and potential for the spread of the disease is also in Asia, where many rural families have at least a few chickens that typically roam free instead of living in an enclosure. But health officials report that the disease has gotten hardier and more infectious, and they worry that it may mutate and become a bigger threat to people.

If the virus gained the ability to infect people more easily and to move from person to person, it could cause a pandemic -- a global epidemic. Scientists warn that a flu pandemic is inevitable and that the world is unprepared for one. No one can predict when a pandemic might strike or whether influenza H5N1 will be the cause.

Health officials in the United States, Europe and other Western countries are assisting Asian nations in managing avian flu and are working to keep the disease from spreading further. The steps that they're taking to try to avoid a pandemic include:

  • Containing or destroying any birds that appear to be infected.
  • Advising people who handle poultry on proper hygiene and biosecurity practices. As more people contract the virus, it becomes more likely that disease will mutate into something more harmful to people.
  • Administering seasonal flu vaccines to people who handle poultry. The flu shot doesn't provide any protection against avian flu, but it does lower the likelihood that someone could be infected with both flu varieties at once, giving the viruses an opportunity to exchange genetic material.
  • Monitoring wild and domestic birds for any signs of infection.
  • Developing a vaccine for avian flu H5N1, which German scientists say should be available in late 2005, and stockpiling antiviral drugs.
  • Banning imports of birds and poultry and quarantining pets and performing animals when they return from countries with reported infections.
  • Recommending that farmers confine free-range poultry and other animals. For example, British officials decided in February of 2006 to keep the ravens that traditionally live at the Tower of London indoors.

Many countries also have plans in place for isolating infected travelers and quarantining anyone who has traveled with them. Response plans also outline how to limit the spread of the disease if a pandemic occurs.

Check out the links below for more information about avian influenza and flu pandemics.

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More Information


  • APHIS: Highly Pathogenic Avian Influenza
  • APHIS Veterinary Services: Highly Pathogenic Avian Influenza
  • CDC: Outbreaks in North America
  • CDC: Questions and Answers Regarding the Executive Order
  • Fox, Maggie. "Bird Flu Virus Shows Signs of Evading Newest Drug." Reuters, October 14, 2005.
  • Hooper, Duncan. "Greece May Have First Bird Flu Case in European Union." Bloomburg, October 17, 2005.
  • INFOSAN: Avian Influenza
  • NIAID: Focus on the Flu
  • NPR: 1918 Killer Flu Reconstructed
  • Russell, Sabin. "Why the Bird Flu's So Dangerous." San Francisco Gate, October 17, 2005.
  • Sipress, Alan. "Bird Flu Drug Rendered Useless." Washington Post, June 18, 2005.
  • WHO: Avian Influenza
  • WHO: Cumulative Number of Confirmed Cases of Avian Influenza
  • WHO: Guidelines for Use of Seasonal Influenza Vaccine
  • WHO: Influenza Frequently Asked Questions
  • WHO: Pandemic Preparedness
  • U.S. Department of Labor: Avian Flu Guidance