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WASHINGTON, January 17, 2016 -- The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the pathogenicity of eight of the nine H7N8 avian influenza detections announced on January 16. The turkey flocks have been confirmed as low pathogenic avian influenza, with additional testing ongoing for the ninth flock.
These January 16 detections were identified as part of surveillance testing in the control area surrounding the initial highly pathogenic H7N8 avian influenza (HPAI) case in that state, identified on January 15.
The pathogenicity of a virus refers to its ability to produce disease. Birds with low pathogenic avian influenza (LPAI) often show no signs of infection or only have minor symptoms. HPAI viruses spread quickly and cause high mortality in domestic poultry. H7 LPAI viruses have been known to mutate into HPAI viruses in the past.
“It appears that there was a low pathogenic virus circulating in the poultry population in this area, and that virus likely mutated into a highly pathogenic virus in one flock,” said Dr. John Clifford, USDA Chief Veterinarian. “Through cooperative industry, state and federal efforts, we were able to quickly identify and isolate the highly pathogenic case, and depopulate that flock. Together, we are also working to stop further spread of the LPAI virus, and will continue aggressive testing on additional premises within the expanded control area to ensure any additional cases of either HPAI or LPAI are identified and controlled quickly.”
APHIS continues to work closely with the Indiana State Board of Animal Health and the affected poultry industry on a joint incident response. State officials quarantined the additional affected premises and depopulation of birds has already begun. Depopulation prevents the spread of the disease. Birds from the flock will not enter the food system.
No human infections associated with avian influenza A viruses of this particular subtype (i.e., H7N8) have ever been reported. As a reminder, the proper handling and cooking of poultry and eggs to an internal temperature of 165 ˚F kills bacteria and viruses, including HPAI.
As part of existing avian influenza response plans, Federal and State partners continue to work on additional surveillance and testing in the nearby area. No new presumptive cases have been identified since January 16.
The rapid testing and response in this incident is the result of months of planning with local, state, federal and industry partners to ensure the most efficient and effective coordination. Since the previous HPAI detections in 2015, APHIS and its state and industry partners have learned valuable lessons to help implement stronger preparedness and response capabilities. In September, APHIS published a HPAI Preparedness and Response Plan that captures the results of this planning effort, organizing information on preparatory activities, policy decisions and updated strategy documents.
The United States has the strongest AI surveillance program in the world, and USDA is working with its partners to actively look for the disease in commercial poultry operations, live bird markets and in migratory wild bird populations.
Anyone involved with poultry production, from the small backyard to the large commercial producer, should review their biosecurity activities to assure the health of their birds. To facilitate such a review, a biosecurity self-assessment and educational materials can be found at http://www.uspoultry.org/animal_husbandry/intro.cfm
In addition to practicing good biosecurity, all bird owners should prevent contact between their birds and wild birds and report sick birds or unusual bird deaths to State/Federal officials, either through their state veterinarian or through USDA’s toll-free number at 1-866-536-7593. Additional information on biosecurity for backyard flocks can be found at http://healthybirds.aphis.usda.gov.
Avian influenza (AI) is caused by an influenza type A virus which can infect poultry (such as chickens, turkeys, pheasants, quail, domestic ducks, geese and guinea fowl) and is carried by free flying waterfowl such as ducks, geese and shorebirds. AI viruses are classified by a combination of two groups of proteins: hemagglutinin or “H” proteins, of which there are 16 (H1–H16), and neuraminidase or “N” proteins, of which there are 9 (N1–N9). Many different combinations of “H” and “N” proteins are possible. Each combination is considered a different subtype, and can be further broken down into different strains. AI viruses are further classified by their pathogenicity (low or high)— the ability of a particular virus strain to produce disease in domestic chickens.