Animal Disease Alert: Avian Influenza
A Threat to U.S. Poultry
Worldwide, there are many strains of avian influenza (AI) virus that can
cause varying amounts of clinical illness in poultry. AI viruses can infect
chickens, turkeys, pheasants, quail, ducks, geese, and guinea fowl, as
well as a wide variety of other birds. Migratory waterfowl have proved
to be the natural reservoir for this disease.
AI viruses can be classified into low pathogenic (LPAI) and highly pathogenic
(HPAI) forms based on the severity of the illness they cause. Most AI
virus strains are LPAI and typically cause little or no clinical signs
in infected birds. However, some LPAI virus strains are capable of mutating
under field conditions
into HPAI viruses, which cause more illness in infected birds. The U.S.
Department of Agriculture’s
(USDA) Animal and Plant Health Inspection Service (APHIS) works to keep
HPAI from becoming established in the U.S. poultry population.
AI can strike poultry quickly without any infection warning signs. Once
established, the disease can spread rapidly from flock to flock. It is
essential for the U.S. poultry industry to be alert to this disease threat.
Clinical Signs
Birds affected with all forms of AI may show one or more of the following
signs:
• Sudden death without clinical signs
• Lack of energy and appetite
• Decreased egg production
• Soft-shelled or misshapen eggs
• Swelling of the head, eyelids, comb, wattles,
and hocks
• Purple discoloration of the wattles, combs,
and legs
• Nasal discharge
• Coughing, sneezing
• Incoordination
• Diarrhea
Introduction and Spread of AI Virus
Exposure of poultry to migratory waterfowl and the international movement
of poultry, poultry equipment,
and people pose risks for introducing AI into U.S. poultry. Once introduced,
the disease can be spread from bird to bird by direct contact. AI viruses
can also be spread by manure, equipment, vehicles, egg flats, crates,
and people whose clothing or shoes have come in contact with the virus.
AI viruses can remain viable at moderate temperatures for long periods
in the environment and can survive indefinitely in frozen material.
Biosecurity Measures on the Farm
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.
• Protect poultry flocks from coming into contact with wild or
migratory birds. Keep poultry away from any source of water that may
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.
• Avoid visiting other poultry farms. If you do visit another
farm or live-bird market, change footwear
and clothing before working with your own flock.
• Do not bring birds from slaughter channels, especially live-bird
markets, back to the farm.
Report Suspicious Signs
If birds exhibit clinical signs of AI or may have been exposed to birds
with the disease, immediately notify Federal or State animal health officials.
The U.S. Department of Agriculture is an equal opportunity provider
and employer.
APHIS 81–35–007
June 2002
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