We've been very lucky that it has been over a year since the last outbreak of HPAI avian flu was reported in a commercial flock here in the United States (see APHIS: HPAI H7N8 In Commerical Turkey Farm - Indiana). In that case, it was determined that a low path H7N8 avian influenza virus mutated into a high path virus after it was introduced into a commercial poultry flock.
That incident produced 1 HPAI outbreak, and 10 LPAI outbreaks, all in the same county (see J. Virology: Pathogenesis & Transmission Assessments Of HPAI & LPAI H7N8 Viruses).
Today APHIS has announced the detection of a new HPAI H7 outbreak (“N-type” yet to be determined) in a commercial chicken breeder flock in Lincoln County, Tennessee (see map above). Affected are 73,000 birds, which will be destroyed. We should learn more about the full subtype in the next 24-48 hours.
First the statement from APHIS, then I'll return with a bit more.
USDA Confirms Highly Pathogenic H7 Avian Influenza in a Commercial Flock in Lincoln County, TennesseeContacts:
Donna Karlsons, 301-851-4107
Lyndsay Cole, 970-494-7410
March 5, 2017, Washington – The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of highly pathogenic H7 avian influenza (HPAI) of North American wild bird lineage in a commercial chicken breeder flock in Lincoln County, Tennessee. This is the first confirmed case of HPAI in commercial poultry in the United States this year. The flock of 73,500 is located within the Mississippi flyway.
Samples from the affected flock, which experienced increased mortality, were tested at Tennessee’s Kord Animal Health Diagnostic Laboratory and confirmed at the APHIS National Veterinary Services Laboratories (NVSL) in Ames, Iowa. Virus isolation is ongoing, and NVSL expects to characterize the neuraminidase protein, or “N-type”, of the virus within 48 hours.
APHIS is working closely with the Tennessee Department of Agriculture on a joint incident response. State officials quarantined the affected premises and birds on the property will be depopulated to prevent the spread of the disease. Birds from the flock will not enter the food system.
The Tennessee Department of Agriculture is working directly with poultry workers at the affected facility to ensure that they are taking the proper precautions to prevent illness and contain disease spread. As a reminder, the proper handling and cooking of poultry and eggs to an internal temperature of 165 ˚F kills bacteria and viruses.
As part of existing avian influenza response plans, Federal and State partners are working jointly on additional surveillance and testing in the nearby area. 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.
USDA will be informing the World Organization for Animal Health (OIE) as well as international trading partners of this finding. USDA also continues to communicate with trading partners to encourage adherence to OIE standards and minimize trade impacts. OIE trade guidelines call on countries to base trade restrictions on sound science and, whenever possible, limit restrictions to those animals and animal products within a defined region that pose a risk of spreading disease of concern.
These virus strains can travel in wild birds without them appearing sick. People should avoid contact with sick/dead poultry or wildlife. If contact occurs, wash your hands with soap and water and change clothing before having any contact with healthy domestic poultry and birds.
All bird owners, whether commercial producers or backyard enthusiasts, should continue to practice good biosecurity, 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 can be found at www.aphis.usda.gov/animalhealth/defendtheflock.
The map below shows the four main migratory flyways which funnel birds from their summer nesting grounds in Alaska, Northern Canada and the Arctic each fall south to the continental United States and beyond. In the spring, the migration returns north.
While these flyways are predominately north-south corridors, their overlapping allows for a lateral (east-west) movement of avian viruses as well – often via shared nesting areas and ponds.
We'll have to wait to learn whether today's outbreak will be limited to one farm, exactly what subtype is involved, and whether it was sparked by an HPAI virus, or if an LPAI H7 virus mutated to HP status after it was introduced.
In the meantime, for more on migratory birds - and their ability to carry and spread avian flu viruses - you may wish to revisit: