#16,517
Last Friday the USDA announced the first detection the Eurasian H5N1 virus (clade 2.3.4.4b) in the United States since 2016; in a wild American wigeon in Colleton County, South Carolina. This followed similar detections in wild and captive birds in Newfoundland, Canada in late December and early January (see here, and here).
In late 2014, we saw the long-feared incursion of HPAI H5Nx from Asia into North America (see EID Journal: Novel Eurasian HPAI A H5 Viruses in Wild Birds – Washington, USA) which sparked the largest avian epizootic in American history, eventually spreading to 15 states (see map below).On Sunday, in Preprint: Transatlantic Spread of HPAI H5N1 by Wild Birds from Europe to North America in 2021, we looked at an initial report linking the Canadian detection to the ongoing HPAI H5 epizootic in Europe, which has affected millions of wild and captive birds over the past 18 months.
While HPAI H5N1 has only been detected in wild birds in the United States this winter, late yesterday the USDA confirmed two additional detections; a second bird in Colleton County, South Carolina and one collected in Hyde County, North Carolina nearly 500 km to the north and east.
First, the USDA announcement, after which I'll have more.
USDA Confirms Additional Highly Pathogenic Avian Influenza Finds in Wild Birds
Published: Jan 18, 2022
Contact:
APHISpress@usda.gov
WASHINGTON, January 18, 2022 – The United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed two additional findings of highly pathogenic avian influenza (HPAI) in wild birds – one in Colleton County, South Carolina and one in Hyde County, North Carolina. These finds follow confirmation on January 14, 2022 of HPAI in a wild bird in Colleton County, South Carolina. All three findings are H5N1 HPAI.
These findings are not unexpected, as wild birds can be infected with HPAI and show no signs of illness. They can carry the disease to new areas when migrating. APHIS anticipates additional wild bird findings as our robust wild bird sampling program continues into the spring.
APHIS will post these and all future wild bird findings on its website on a weekly basis. Stakeholders should check the website on a routine basis, as no future stakeholder announcements are planned for wild bird findings.
Since wild birds can be infected with these viruses without appearing sick, people should minimize direct contact with wild birds by using gloves. If contact occurs, wash your hands with soap and water, and change clothing before having any contact with healthy domestic poultry and birds. Hunters should dress game birds in the field whenever possible and practice good biosecurity to prevent any potential disease spread. Biosecurity information is available at: https://www.aphis.usda.gov/publications/animal_health/2015/fsc_hpai_hunters.pdf.
Given these additional findings, anyone involved with poultry – commercial or backyard flocks alike – should review their biosecurity plan and enhance their biosecurity practices to assure the health of their birds. APHIS has materials about biosecurity, including videos, checklists, and a toolkit available for producers on our website.
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.
Additional background
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 which circulate within flyways/geographic regions. AI viruses are further classified by their pathogenicity (low or high)—the ability of a particular virus strain to produce disease in domestic chickens.
These Eurasian HPAI H5Nx viruses - while sharing the same subtype as their more pathogenic Asian counterparts (H5N1, H5N6) - are from a different lineage, and have not shown anywhere near the same level of pathogenicity in humans as their more famous cousins.
They do continue to evolve, and mutate, however. And in recent years we've seen signs of increased zoonotic potential (see UKHSA Statement On Human H5 Infection In England), making their public health threat low, but not zero.
While we've been lucky so far - with no large bird die offs reported, or outbreaks in poultry - the impacts from the 2015 North American avian epizootic are well remembered, and the USDA is urging enhanced biosecurity for both commercial and private poultry holdings.
The USDA has some advice on how to Defend The Flock at the website below.
