Tennessee Department of Agriculture officials have confirmed the discovery of a second poultry farm infected with avian H7N9, albeit in an LPAI (Low Pathogenic) form, in adjacent Giles County.
LPAI viruses are commonly found in wild and migratory birds, and often only produce mild symptoms in poultry. The concern is - when LPAI H5 and H7 viruses are not quickly controlled - they have the potential to mutate into highly pathogenic strains.
Hence all H5 & H7 outbreaks are reportable to the OIE, and must be quickly eradicated.Over the past couple of years we've seen an unusual number of spontaneous LPAI-to-HPAI mutations, both in Europe (see here, here, and here) and last year in the H7N8 outbreaks in Indiana (see Genome Announcements: LPAI-to-HPAI Mutation Cited in January's H7N8 Outbreak).
Between these two H7N9 outbreaks, and the report of LPAI H5N2 earlier this week on a Wisconsin turkey farm, the word is going out to poultry farmers across the nation to review, and tighten up, their biosecurity measures.
Thursday, March 09, 2017
NASHVILLE — The state veterinarian confirms that a flock of chickens at a commercial poultry breeding operation has tested positive for low pathogenic avian influenza (LPAI).
This chicken breeding operation is located in Giles County, Tenn. The company that operates it is a different company from the one associated with the recent detection of highly pathogenic avian influenza (HPAI) in Lincoln County. At this time, officials do not believe one premises sickened the other.
On March 6, routine screening tests at the Giles County premises indicated the presence of avian influenza in the flock. State and federal laboratories confirmed the existence of H7N9 LPAI in tested samples.
“This is why we test and monitor for avian influenza,” State Veterinarian Dr. Charles Hatcher said. “When routine testing showed a problem at this facility, the operators immediately took action and notified our lab. That fast response is critical to stopping the spread of this virus.”
As a precaution, the affected flock was depopulated and has been buried. The premises is under quarantine. Domesticated poultry within a 10 kilometer (6.2 mile) radius of the site are also under quarantine and are being tested and monitored for illness. To date, all additional samples have tested negative for avian influenza and no other flocks within the area have shown signs of illness.
The primary difference between LPAI and HPAI is mortality rate in domesticated poultry. A slight change to the viral structure can make a virus deadly for birds. Avian influenza virus strains often occur naturally in wild migratory birds without causing illness in those birds. With LPAI, domesticated chickens and turkeys may show little or no signs of illness. However, HPAI is often fatal for domesticated poultry.
The Giles County LPAI incident is similar to the Lincoln County HPAI incident in that both the low pathogenic and highly pathogenic viruses are an H7N9 strain of avian influenza. USDA’s National Veterinary Services Laboratories confirms the H7N9 virus that affected the Lincoln County premises is of North American wild bird lineage. It is not the same as the China H7N9 virus affecting Asia and is genetically distinct.
The Lincoln County premises affected by HPAI remains under quarantine. To date, all additional poultry samples from the area surrounding that site have tested negative for avian influenza and no other flocks within the area have shown signs of illness. Testing and monitoring continues.
Neither LPAI nor HPAI pose a risk to the food supply. No affected animals entered the food chain. The risk of a human becoming ill with avian influenza during poultry outbreaks is very low. However, out of an abundance of caution, officials with the Tennessee Department of Health and Tennessee Department of Agriculture are working together to monitor the health of individuals who are working on either premises or had contact with affected birds.
The plan for the control of avian influenza includes coordination of local, county, state and federal resources and response, and protocols for quarantine, testing, disposal, cleaning, disinfection and monitoring.
Owners of commercial and backyard poultry flocks are encouraged to closely observe their birds.
Report a sudden increase in the number of sick birds or bird deaths to the state veterinarian’s office at 615- 837-5120 and/or USDA at 1-866-536-7593.
Prevent contact with wild birds.
Practice good biosecurity with your poultry.
Enroll in the National Poultry Improvement Plan.
Follow Tennessee’s avian influenza updates and access resources for producers and consumers.
The state veterinarian and staff are focused on animal health and disease prevention. Each year, the Kord Animal Health Diagnostic Laboratory tests approximately 22,000 samples from poultry for avian flu.