USDA and Centers for Disease Control officials on Wednesday addressed key questions surrounding the late-winter outbreak of Highly Pathogenic Avian Influenza in the U.S., including how the disease may continue to spread and what will be able to stop it.
Answering questions on April 22 were Dr. John Clifford, USDA Chief Veterinary Officer; Dr. Alicia Fry, CDC National Center for Immunization and Respiratory Diseases, Influenza Division, Epidemiology and Prevention Branch Medical Officer; and Dr. David Swayne, USDA Southeast Poultry Research Lab Director.
How many birds have been infected?
According to USDA's Clifford, about 3.5 million birds have been depopulated so far, not including a recent identification of 5.3 million infected birds at an Iowa hen facility.
What avian flu symptoms can poultry producers watch for?
Turkeys often go off feed and may appear lethargic within a few hours, Clifford said. They subsequently have a "star-gazing" appearance, where they contort their necks and may die quickly.
In chickens, Clifford said egg production may drop and symptoms similar to turkeys appear.
How can producers protect their flocks?
Poultry producers may protect their flocks from HPAI by ensuring vehicles entering facilities are properly cleaned and disinfected, as are workers' boots and hands, Clifford said. Workers are encouraged to clean their footwear and hands even when moving between barns on the same property. Domestic birds also should be protected from wild birds and water fowl.
Protection of backyard birds is more difficult as they might not be as controlled, but enclosure is beneficial. Birds should be provided with municipal water if possible as surface water from ponds or lakes could be contaminated by wild birds, Swayne added.
How are infected flocks destroyed?
Infected flocks can be destroyed using foam euthanasia, if they are housed on the ground. For laying facilities, CO2 is being considered as a humane euthanasia tool, Clifford said.
When will avian flu outbreaks ease?
The virus does not survive easily in hot weather, Clifford said, and Swayne noted that ultraviolet light from sunshine will help kill the influenza virus on dust particles or surfaces.
The number of cases may start to drop depending on the temperature and also the humidity in the air. Dryness helps reduce the life of the virus.
Is avian flu a risk to humans?
Avian H5 viruses are different that those that have previously appeared globally, and have not caused any known infections in humans, Fry said. CDC as of April 22 considered the risk to be "low," however Fry said the agency cannot rule out the possibility of a human infection. Previously, most human infections with avian influenza occur in people who have prolonged and frequent contact with birds, she noted.
Observe wild birds only from a distance and avoid contact with domestic birds that appear sick, Fry said. Poultry products and wild birds are safe to eat if they are properly handled and cooked to a temperature of 165 degrees F, according to USDA.
What's being done to prepare for avian flu outbreaks in people?
Though Fry reiterated the low risk of this strain of avian flu impacting humans, she said the CDC has prepared candidate vaccine viruses that may be used to create a vaccine for people if needed. This is part of preparedness planning for any disease outbreak, she said.
Genetic analysis has not shown any markers that are related to infection among humans, she said.
What is being done to prepare for more outbreaks in birds?
USDA has been expanding research on avian influenza, including tests to detect HPAI, Swayne said. Several ongoing studies are reviewing transmission of HPAI from bird-to-bird and the USDA Southeast Poultry Research Lab is also reviewing bird flu vaccines.
For more information on HPAI, visit the following Web resources: