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Avian Influenza FAQs


Pet Column for the week of October 18, 2005

Related information:

Services - Public Health

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Yvette J. Johnson, DVM, MS, PhD
Assistant Professor, Clinical Epidemiology
Poultry Spe

What is avian influenza?
Why is avian influenza currently raising concerns?
Where is the current outbreak of avian influenza happening?
How do birds get avian influenza?
How do people get avian influenza?
Is there a vaccine or cure for avian influenza in people?
Can other animals get this strain of avian influenza?
Is it safe to eat poultry and eggs?
What is the United States doing to prevent avian influenza in commercial poultry populations?
References


What is avian influenza?
Avian influenza, also known as bird flu, fowl pest, or fowl plague, is a respiratory disease of birds caused by a Type A influenza virus. It occurs world wide and was first described more than 100 years ago in Italy.

In birds signs of avian influenza may range from mild respiratory signs, such as coughing and sneezing, to very rapidly spreading severe illness resulting in death of all infected individuals.
There are 15 strains of influenza virus that are known to infect birds. Usually birds and pigs are the only species affected. However, some strains, such as the H5N1 virus that is currently causing outbreaks in Asia, can cause disease in other mammals.

Why is avian influenza currently raising concerns?
Influenza viruses mutate rapidly. A mutation can cause an outbreak to shift from causing only mild illness in birds to causing rapid high mortality rates. A viral mutation during the course of an epidemic may also alter which species can be infected by the virus. Avian influenza is currently of concern because more than 100 people have been infected with the H5N1 virus over the past 2 years, resulting in 60 human deaths.

However, avian influenza will not become widespread in people unless the virus gains the ability to be transmitted from person to person easily. When human or swine populations are infected by more than one strain of influenza virus at the same time, these non-avian species can serve as a "mixing vessel" for the mutation and spread of a strain that can be transmitted easily between humans.
To date this has not occurred. Almost all of the human cases have been traced to close contact between humans and live poultry or ducks.

Where is the current outbreak of avian influenza happening?
Between December 2003 and October 10, 2005, H5N1 avian influenza was isolated from birds in Cambodia, China, Hong Kong, Indonesia, Japan, Kazakhstan, Korea, Laos, Malaysia, Mongolia, Romania, Russia, Thailand, Turkey, and Vietnam.

The first reported case of H5N1 avian influenza in humans occurred in Hong Kong in 1997. Between December 2003 and October 10, 2005, a total of 117 human cases of H5N1 avian influenza were confirmed worldwide. These occurred in Cambodia, Indonesia, Thailand, and Vietnam and resulted in 60 human deaths.

How do birds get avian influenza?
Migratory waterfowl, such as wild ducks, are the natural reservoir for avian influenza and are the most resistant to clinical disease, meaning that they can carry and spread the virus without showing any signs of illness themselves. The feces of infected waterfowl are the likely source of some outbreaks of avian influenza in domestic birds. Domestic ducks may also carry the virus and infect other birds.

The virus is shed in saliva, nasal secretions, and feces. Respiratory droplets and dust contaminated with the virus spread the disease to other birds. Footwear, supplies, vehicles, and equipment that are contaminated with bird droppings or feathers and dust from infected birds can also spread the disease from one place to another.

How do people get avian influenza?
Presently, the H5N1 avian influenza virus does not spread easily from person to person. Human beings who have contracted the disease had close contact with infected, live poultry or ducks or handled equipment that was contaminated with feces, feathers, or dust from infected birds. (See also "Is it safe to eat poultry and eggs?" below.)

Is there a vaccine or cure for avian influenza in people?
There is currently no vaccine available to protect people from avian influenza. The human influenza vaccine will not offer protection against avian influenza. A vaccine was developed for the 1997 H5N1 avian influenza; unfortunately, the virus has changed considerably since then and that vaccine is not recommended for use against the current strain.

Nevertheless, it is a good idea to follow the recommendations of the Centers for Disease Control and Prevention regarding flu shots. If more people are protected against human influenza, there will be less opportunity for the avian influenza virus to infect someone with human flu and develop the capacity to spread easily from person to person.

The antiviral drug Tamiflu (Roche) is the most effective treatment for avian influenza in human beings. However, it must be administered within 40 hours of the onset of clinical signs to be effective, and supplies of this drug are limited.

Can other animals get this strain of avian influenza?
Yes, reports indicate that in addition to affecting chickens, ducks, swine, and human beings this strain may affect domestic cats, tigers, leopards, ferrets, eagles and falcons. Work is under way to determine the extent to which other wildlife and domestic species may be infected. It is believed that all birds can transmit avian influenza to some extent. Therefore, the U.S. restricts importation of all birds (Class Aves) and feathers from countries affected by the outbreak of avian influenza. This should prevent the disease from being introduced into the U.S. by exotic bird species or pet birds.

Is it safe to eat poultry and eggs?
There have been no reported human cases of avian influenza associated with the preparation or consumption poultry meat or eggs.

In countries where the outbreak is currently ongoing, the chickens affected have been from small backyard flocks and communities in which free-range chickens and ducks co-mingle. Avian influenza has not been reported in large-scale commercial poultry operations. Backyard and free-range poultry are more likely to come into contact with wildlife carriers and their droppings, so they are at increased risk for being exposed to avian influenza virus.

In areas where the outbreak is ongoing, people should avoid contact with sick and dying birds and use proper hygiene when handling live poultry and preparing them for consumption. The virus is inactivated by heat, so adequate cooking of the meat and poultry will further prevent transmission of the disease to people.

What is the United States doing to prevent avian influenza in commercial poultry populations?
To date the United States does not have H5N1 avian influenza, and it does not import poultry from the affected countries. In addition, several safeguards are in place in the United States to protect the health of chickens on farms and to ensure the quality of poultry and eggs purchased by consumers. In modern commercial poultry and egg production systems, birds are housed indoors in climate-controlled buildings to prevent contact with wildlife that may spread diseases that the chickens are susceptible to, including avian influenza.

There is ongoing surveillance of flocks to test birds that show signs of respiratory disease or unexpected mortality. If a flock is suspected of having avian influenza, the farm is placed under quarantine until the diagnosis is confirmed. If the diagnosis is confirmed, restrictions are placed on the movements of birds, equipment, and personnel to and from the facility and the flock will be de-populated on-site. Birds from infected farms are not sent for processing or sold for consumption. An investigation is conducted to determine the source of the virus, and any flocks thought to be at risk of contamination are also placed under quarantine and may be de-populated as a preventive measure. Farms in areas where an outbreak is ongoing do not receive new chickens until the area is determined to be free of disease.

So, the risk of H5N1 avian influenza moving from backyard flocks in Asia to commercial flocks in the United States is probably low. If an outbreak in birds in the United States does occur, the risk of American consumers being exposed to the virus from handling or consuming poultry meat or eggs is remote.


References and for more information:
http://www.who.int/csr/disease/avian_influenza/en/
http://www.nationalchickencouncil.com/files/QandAonAI.pdf
http://www.who.int/mediacentre/factsheets/avian_influenza/en/print.html
http://www.cdc.gov/flu/avian/
http://www.fao.org/ag/againfo/subjects/en/health/diseases-cards/special_avian.html
http://www.nwhc.usgs.gov/pub_metadata/field_manual/field_manual.html
http://www.news.cornell.edu/stories/Oct05/Avian_Torres.kr.html