 What
is avian influenza?
Avian influenza (AI) is a disease found among poultry. AI viruses can
infect chickens, turkeys, pheasants, quail, ducks, geese and guinea fowl
as well as a wide variety of other birds, including migratory waterfowl.
Each year, there is a flu season for birds just as there is for humans
and, as with people, some forms of the flu are worse than others.
AI viruses can be classified into low pathogenicity and highly pathogenic
forms based on the severity of the illness they cause in poultry. Most
AI strains are classified as low pathogenicity avian influenza (LPAI)
and cause few clinical signs in infected birds. In contrast, high pathogenicity
avian influenza (HPAI) causes a severe and extremely contagious illness
and death among infected birds.
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Besides
HPAI and LPAI, is avian influenza divided into other groupings?
Yes, there are 144 different characterizations of the virus based on
two groups of proteins found on the surface of the virus. One group is
the hemagglutinin proteins (H), of which there are 16 different types
(H1-H16); the other group is the neuraminidase proteins (N), of which
there are 9 different types (N1-N9). The virus detected in several Asian
and European countries is an H5N1 type of highly pathogenic (HPAI) virus.
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How
is the disease spread?
AI is primarily spread by direct contact between healthy birds and infected
birds, and through indirect contact with contaminated equipment and materials.
The virus is excreted through the feces of infected birds and through
secretions from the nose, mouth and eyes.
Contact with infected fecal material is the most common of bird-to-bird
transmission. Wild ducks often introduce low pathogencicity into domestic
flocks raised on range or in open flight pens through fecal contamination.
Within a poultry house, transfer of the HPAI virus between birds can also
occur via airborne secretions. The spread of avian influenza between poultry
premises almost always follows the movement of contaminated people and
equipment. AI also can be found on the outer surfaces of egg shells. Transfer
of eggs is a potential means of AI transmission. Airborne transmission
of virus from farm to farm is highly unlikely under usual circumstances.
HPAI can be spread from birds to people as a result of extensive direct
contact with infected birds. Broad concerns about public health relate
to the potential for the virus to mutate, or change into a form that could
spread from person to person. The U.S. Department of Health and Human
Services is aggressively working to ensure public health is protected.
More information about the joint efforts of the federal government is
available at http://www.pandemicflu.gov
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What
symptoms do birds with AI demonstrate?
LPAI symptoms are typically mild. Decreased food consumption, respiratory
signs (coughing and sneezing) and a decrease in egg production might demonstrate
the presence of the disease. Birds that are affected with HPAI have a
greater level of sickness and could exhibit one or more of the following
clinical signs: sudden death; lack of energy and appetite; decreased egg
production; soft-shelled or misshapen eggs; swelling; purple discoloration;
nasal discharge; coughing, sneezing; lack of coordination and diarrheA.
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What
should producers do if their birds appear to have signs of AI?
If birds exhibit clinical signs of HPAI or might have been exposed to
birds with the disease, producers or bird owners should immediately notify
Federal or State animal health officials.
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Is
it possible for an LPAI strain to become highly pathogenic?
Some low pathogenic subtypes have the capacity to mutate into more virulent
strains. While LPAI is considered lower risk, low pathogenic strains of
the virus - the H5 and H7 strains - can mutate to highly pathogenic forms.
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Is
AI a reportable disease?
HPAI is considered a reportable disease by the World Organization for
Animal Health (OIE). OIE has developed animal health standards that classify
all H5 and H7 viruses as reportable diseases.
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Does
AI threaten human health?
LPAI poses no known serious threat to human health, however some strains
of HPAI viruses can be infectious to people. Since December 2003, a growing
number of Asian countries have reported outbreaks of HPAI in chickens
and ducks. Humans also have been affected, most of who had direct contact
with infected birds. The rapid spread of HPAI in 2004 and 2005 is historically
unprecedented and of growing concern for human health as well as for animal
health.
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Does
HPAI currently exist in the United States? Has it ever occurred in this
country?
Incidents of LPAI are commonly detected in domestic poultry flocks. LPAI
does not pose a serious threat to human health.
There is no evidence that HPAI currently exists in the United States.
Historically, there have been three HPAI outbreaks in poultry in this
country--in 1924, 1983 and 2004. No significant human illness resulted
from these outbreaks.
The 1924 H7 HPAI outbreak was detected in and contained to East Coast
live bird markets.
The 1983-84 H5N2 HPAI bird outbreak resulted in the destruction of approximately
17 million chickens, turkeys, and guinea fowl in the northeastern United
States to contain and eradicate the disease.
In 2004, USDA confirmed an H5N2 HPAI outbreak in chickens in the southern
United States. The disease was quickly eradicated thanks to close coordination
and cooperation between USDA, state, local, and industry leaders. Because
of the quick response, the disease was limited to one flock.
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What
kind of test is used to diagnose avian influenza in birds?
Samples are usually taken by swabbing the mucus that coats the throat
of live birds, which does not harm the birds. With wild birds, a fecal
sample can be taken instead. These samples go into sealed tubes and are
taken to USDA-approved laboratories where a polymerase chain reaction
(PCR) test is run. A PCR test is a rapid method of identifying the virus,
typically producing results within 3 hours. If a sample from an area where
avian influenza has not been previously detected tests positive on a rapid
test, an additional confirmatory test is performed. This test involves
growing the sample in embryonated chicken eggs, which then provides the
material to allow detailed identification of the strain of virus and whether
it is HPAI (high pathogenicity) or LPAI (low pathogenicity). This test
can take 3-5 days to produce results.
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What
is USDA doing to prevent the introduction of HPAI into the United States?
USDA recognizes that HPAI poses a significant threat to animal health
and has the potential to threaten human health. Accordingly, USDA has
safeguards in place to protect against the introduction of HPAI into the
United States. USDA maintains trade restrictions on the importation of
poultry and poultry products from countries currently affected by H5N1
HPAI.
Detection USDA also works closely with international organizations like
the World Organization for Animal Health (OIE), the United Nations' Food
and Agriculture Organization (FAO), and World Health Organization (WHO)
to assist HPAI-affected countries and other neighboring Asian-Pacific
countries with disease prevention, management, and eradication activities.
By helping these countries prepare for, manage, or eradicate HPAI (H5N1)
outbreaks, USDA can reduce the risk of the disease spreading from overseas
to the United States.
USDA recognizes that prevention is only one part of a comprehensive strategy
and therefore continues to work closely with its Federal, State, and Tribal
partners and industry stakeholders to have effective and coordinated emergency
response plans at the ready should an outbreak of HPAI occur in the United
States.
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What
is USDA doing to monitor the U.S. for AI among birds?
The USDA works with federal, state, and industry leaders to monitor and
respond to outbreaks of LPAI. APHIS has provided funding and support personnel
to states when LPAI has been detected. When HPAI is detected, APHIS personnel
are primary responders, due to its infectivity and high mortality rate
among poultry. Close attention is also given to two subtypes of LPAI,
the H5 and H7 strains, because of the potential for them to mutate into
HPAI. The AI strain infecting both birds and humans in Asia is the HPAI
H5N1. There is presently no evidence of HPAI H5N1 existing in the U.S.
- neither in animals nor humans.
In addition to international import restrictions, APHIS and State veterinarians
are specially trained to diagnose foreign animal diseases regularly conduct
field investigations of suspicious disease conditions. This surveillance
is assisted by university personnel, State animal health officials, USDA-accredited
veterinarians, and members of the industry who report suspicious cases.
APHIS and State animal health officials work cooperatively with the poultry
industry to conduct surveillance at breeding flocks, slaughter plants,
live-bird markets, livestock auctions, and poultry dealers.
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What
can poultry producers do to prevent an AI outbreak on their farms?
Poultry producers should strengthen biosecurity practices to prevent
the introduction of AI into their flocks. The following are some sound
biosecurity practices:
- Keep an "all-in, all-out" philosophy of flock management.
Avoid skimming flocks-birds left behind are exposed to work crews and
equipment that could carry poultry disease viruses. Process each lot
of birds separately, and clean and disinfect poultry houses between
flocks.
- Protect poultry flocks from coming into contact with wild or migratory
birds. Keep poultry away from any source of water that could have been
contaminated by wild birds.
- Permit only essential workers and vehicles to enter the farm.
- Provide clean clothing and disinfection facilities for employees.
- Thoroughly clean and disinfect equipment and vehicles (including tires
and undercarriage) entering and leaving the farm.
- Do not loan to, or borrow equipment or vehicles from, other farms.
- Change footwear and clothing before working with your own flock after
visiting another farm or
live-bird market or avoid visiting another bird farm if possible.
- Do not bring birds from slaughter channels, especially those from
live-bird markets, back to the farm.
If AI is detected, farms must be thoroughly cleaned and disinfected. AI
is inactivated by heat and drying and it is also very sensitive to most
disinfectants and detergents. The area to be disinfected must be clear of
organic material, which greatly increases the resistance of avian influenza
virus' resistance to disinfection.
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Does
proper food handling prevent avian influenza?
The USDA Food Safety and Inspection Service (FSIS) is working to educate
the public about safe food handling practices in response to numerous
questions from the public about the human risk associated with avian influenzA.
There is no evidence that LPAI can be transmitted to people by eating
poultry. If HPAI were detected in the U.S., the chance of infected poultry
entering the food chain would be extremely low.
Proper handling and cooking of poultry provides protection against this
virus, as it does against many viruses and bacteria, including Salmonella
and E.coli. Safe food handling and preparation is important at all times.
USDA continually reminds consumers to practice safe food handling and
preparation every day:
- Wash hands before and after handling food;
- Prevent cross-contamination by keeping raw meat, poultry, fish, and
their juices away from other foods;
- After cutting raw meats, wash hands, cutting board, knife, and counter
tops with hot, soapy water;
- Sanitize cutting boards by using a solution of 1 teaspoon chlorine
bleach in 1 quart of water;
- Use a food thermometer to ensure food has reached the proper temperature.
Cook whole birds to 180 °F; breasts to 170 °F; drumsticks, thighs
and wings to 180 °F; and a minimum oven temperature of 325 °F.
- Poultry products imported to the U.S. must meet all safety standards
applied to foods produced in the U.S. No poultry from countries with
confirmed cases of H5N1 HPAI can be imported into the United States.
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How
do I get more information about avian influenza?
go to http://www.usda.gov/birdflu
food safety information:
- USDA Meat and Poultry Hotline
- 1-888-MPHotline (1-888-674-6854)
- TTY: 1-800 256-7072
(Source: U.S. Department
of Agriculture)
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