"Bird flu" is the common name for avian influenza, a respiratory disease of birds that is caused by a virus.

There are several different types of avian influenza. The milder forms occur occasionally around the world. These are known as Low Pathogenic Avian Influenza or LPAI. The more serious form is known as Highly Pathogenic Avian Influenza (HPAI) because the disease is much more severe in birds, and it results in high mortality in poultry flocks. The type now the subject of news reporting is specifically called H5N1 HPAI.

Unfortunately, yes. There have been some people in other parts of the world who have developed a form of the disease, nearly all of them from direct contact with live, infected poultry. However, as Dr. Richard Schieber, senior advisor on influenza, Centers for Disease Control and Prevention has stated, "Humans at this moment are very resilient to catching bird flu."

Influenza virus lives mainly in the respiratory system and is spread through droplets of moisture. So far, with only one known, unconfirmed exception, humans have acquired H5N1 HPAI only from very close contact with infected, live birds.

Chickens, ducks and other poultry in other parts of the world are often allowed to run at large in the villages in which people live. Children and other family members tend small flocks of birds to provide eggs and meat. Nearly all of the human cases in other parts of the world are associated with these types of conditions.

It is apparently very easy to prevent human infection from live animals because millions of chickens, ducks and other birds have been culled by soldiers and other workers with no ill effects. There are no cases in which human infection is believed to have resulted from handling poultry meat. Countries most recently affected by H5N1 have not seen the number of cases of bird-to-human transmission seen in early discoveries in Asia.

Scientists say that the virus has not yet developed the ability to pass easily from human to human, and human-to-human transmission is extremely rare, and only by extremely close contact, according to current information.

It is important to deny the virus the opportunity to change and evolve. This is done by stamping it out when it occurs. Affected areas have aggressively destroyed poultry flocks infected with H5N1 HPAI. Experts have said that these countries should discourage the type of loose poultry husbandry that has led to the outbreaks. More importantly, the USA does not import poultry from these areas of the world.

There is no danger of acquiring avian influenza from normally and properly cooked food. Avian influenza is caused by a virus. Like all types of viruses, avian influenza is destroyed by the heat of normal cooking.

No chickens or turkeys known or suspected to be infected with avian influenza are processed for sale as raw meat in the United States. Washing your hands after handling raw poultry is always a good precaution, but consumers in the United States have virtually no chance of encountering meat from a chicken or turkey infected with avian influenza.

Only the H5 and H7 types are known to be able to change from the low-pathogenic form to the highly pathogenic form, so these are the types of greatest concern. Only a few specific avian influenza viruses have been shown to infect humans, and even those infections have been rare. Most of the human cases worldwide have been caused by H5N1 HPAI in other parts of the world and H7N7 in The Netherlands. Some types of avian influenza are so mild that a blood test is needed to confirm that it is present.

We have never had an outbreak of Asian-type H5N1 highly pathogenic avian influenza in the United States, and we do not have any cases now. We had low-pathogenic avian influenza as recently as 2004. The H5N2 outbreak in one flock was designated as highly pathogenic on the basis of a laboratory test, but a more definitive test failed to confirm high pathogenicity. The last confirmed outbreak of H5N2 (not H5N1) highly pathogenic avian influenza in the United States was in Pennsylvania in 1983 and 1984. No known human illness or infections resulted from the outbreak.

The policy of the poultry industry and the government is to eradicate the disease as quickly as possible by destroying any flocks in which the H5 or H7 types of virus are found. The animals are all destroyed and disposed of through environmentally sound methods.

Like all other living things, viruses continue to change and evolve. It is possible that the viruses that cause mild avian influenza could evolve into a more pathogenic form. This is apparently what happened in Pennsylvania in 1983 and 1984, when a low-pathogenic strain turned into a highly pathogenic strain. Flocks are destroyed to prevent the virus from evolving and spreading.

The people involved in destroying flocks wear gloves, masks and protective clothing. Anyone who develops respiratory symptoms reports to a doctor to be checked out. People who have no reason to be on a farm involved in the outbreak are kept away.

Poultry companies and farmers practice strict biosecurity at all times and it is heightened during any outbreak of avian influenza. The trucks carrying feed are hosed down, personnel wear protective clothing and plastic boots and go through footbaths, farmers stay away from community gatherings and generally keep their farms locked down until the problem has passed. The eradication efforts in Virginia, Delaware and Texas in recent years resembled military operations in their scope and precision.

The United States has multiple lines of defense against Asian H5N1 HPAI:

• Transmission from live animals: The importation of birds or bird products from the affected area has been banned or placed under strict control by the U.S. government.
• Transmission from poultry products: None of the affected countries are permitted to export poultry products to the United States. (Virtually all of the chicken and turkey sold in the United States is produced in the United States. The U.S. is a large poultry exporter and imports very little poultry.)
• Transmission via human beings: The virus has not yet developed the ability to pass easily from human to human. If it does so, that will be considered a public health emergency and appropriate steps will be taken, presumably including restrictions on travel from the affected areas. It is possible that infected humans could bring the H5N1 highly pathogenic avian influenza from other parts of the world to the United States. However, no one who has been to the affected areas will be allowed to set foot on a poultry farm in the United States. In addition, President Bush has taken the precaution of adding this type of avian influenza to the list of diseases for which a person can be quarantined while attempting to enter the United States.

Asian H5N1 highly pathogenic avian influenza is the form of the disease that is of the greatest concern. However, other forms do exist and are considered a long-term threat to the poultry industry. The U.S. Congress has appropriated $23 million to the U.S. Department of Agriculture to begin to implement a long-term, domestic avian influenza control program. The Bush administration has asked Congress to maintain that funding for 2006. Recently, Tyson Foods, along most of the rest of the U.S. commercial chicken industry, began testing every flock of chickens, before they’re brought to the processing plant, for the presence of Avian Influenza (AI, or “bird flu”). If this testing indicates evidence of H5 or H7 strains of AI, the farm will be quarantined and the flocks destroyed on the farm.

The modern type of animal production used in the United States is actually very protective of birds and their health. In the United States, chickens and turkeys are usually raised in enclosed buildings called growout houses. More than 20,000 chickens or 4,000 turkeys are placed in a single building. Yet the health of the poultry flocks today is probably better than it has ever been. This is because of improvements in poultry housing, selective breeding for disease resistance, protection from potential disease carriers such as wild birds and continuous health oversight by poultry veterinarians. In contrast, the chickens in many other parts of the world are raised in a manner that has changed little in hundreds of years. They are fully exposed to the environment and to potential disease carriers, and they have minimal or no access to veterinary medical care.