1st Detection of HPAI H5 In the Mississippi Flyway
In what can only be viewed as an troubling sign for the poultry industry, the recently arrived HPAI H5N2 avian flu virus – a new reassortant of the H5N8 virus which first appeared in Asia in early 2014 – has dramatically leapfrogged hundreds of miles east and has infected a commercial turkey farm in Minnesota.
Although this subtype is not known to infect humans, this is a highly pathogenic virus in domestic poultry, and it continues to spread quickly around the world via asymptomatic wild and migratory birds.
Since November we’ve seen H5N8 and/or H5N2/H5N1 turn up in six western states as well as in British Columbia – all of which lie either beneath, or adjacent to, the Pacific Flyway.
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 – something we’ve looked at recently in The North Atlantic Flyway Revisited & FAO On The Potential Threat Of HPAI Spread Via Migratory Birds.
The Mississippi Americas Flyway covers 2/3rds of North America, and is overlapped by the Pacific Flyway on its western border, and the the Atlantic Americas Flyway on the east.
With HPAI H5 now detected in the upper Midwest, the concern has to be how much farther will these viruses spread, and how well entrenched will they become in North American birds.
First Finding in the Mississippi Flyway
The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of highly pathogenic H5N2 avian influenza in a commercial turkey flock in Pope County, Minnesota. This is the first finding in the Mississippi flyway. It is the same strain of avian influenza that has been confirmed in backyard and wild birds in Washington, Oregon and Idaho as part of the ongoing incident in the Pacific flyway.
Samples from the turkey breeder replacement flock, which experienced increased mortality, were tested at the University of Minnesota Veterinary Diagnostic Laboratory and the APHIS National Veterinary Services Laboratories in Ames, Iowa confirmed the finding. APHIS is partnering closely with the Minnesota Board of Animal Health on a joint incident response. State officials quarantined the affected premises and the remaining birds on the property will be depopulated to prevent the spread of the disease. Birds from the involved flock will not enter the food system.
CDC considers the risk to people from these HPAI H5 infections in wild birds, backyard flocks, and commercial poultry, to be low. No human infections with these viruses have been detected at this time. The Minnesota Department of Health is working directly with poultry workers at the affected facility to ensure they are taking the proper precautions. As a reminder, the proper handling and cooking of poultry and eggs to an internal temperature of 165 ˚F kills bacteria and viruses.
Federal and State partners are working jointly on additional surveillance and testing in the nearby area, following existing avian influenza response plans. 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 OIE and 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 to report sick birds or unusual bird deaths to State/Federal officials, either through your 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 healthybirds.aphis.usda.gov
Over the past year we’ve seen the unprecedented global spread of HPAI H5 viruses (primarily H5N8 & H5N2), with novel reassortants winging their way from Asia, to Europe and North America via wild and migratory birds.
While none of these North American reassortants appears to pose a threat to human health, the CDC remains cautious and has issued specific guidance documents (see CDC Interim Guidance For Testing For Novel Flu & CDC Interim Guidance On Antiviral Chemoprophylaxis For Persons With Exposure To Avian Flu).
The concern – beyond HPAI H5’s considerable threat to the poultry industry – is that these viruses are constantly changing. They can hook up with other influenza viruses and reassort – producing new hybrid strains - possibly with unpredictable results.
Shift, or reassortment, happens when two different influenza viruses co-infect the same host swap genetic material.
This rapid emergence and spread of a variety of H5 avian viruses (H5N1, H5N2, H5N2, H5N5, H5N6, H5N8) over the past 12 months recently prompted the World Health Organization to issue a pointed warning (see WHO: H5 Currently The Most Obvious Avian Flu Threat).
While no one can predict the future for any of these viruses - the greater the diversity of novel viruses in circulation - the greater the chances of someday seeing one successfully adapt to humans.
For more on this rapidly expanding array of novel flu viruses you may wish to revisit: