Global update on the 2021-2022 Avian Influenza (H5N1) outbreaks
Global outbreaks of seasonal avian influenza among wild birds and poultry occur periodically, however, in the past 15 years, there has been a rise in the frequency and geographic distribution of avian influenza A virus infections. Particularly since 2013, a wider avian species range has been impacted by a broader array of influenza A variants and subtypes. Most avian influenza A viruses produce no or few signs in infected wild birds, and cause either no or mild disease in poultry (e.g. ruffled feathers, reduced feed and water intake, decreased egg production). Such mild impacts are characterized as resulting from infection by Low Pathogenicity Avian Influenza (LPAI).
However, since 2020, there has been a worldwide increase in the number of High Pathogenicity Avian Influenza (HPAI) infections. This form of influenza leads to disease affecting multiple organ systems and mortality rates exceeding 90% among poultry flocks within 24-48 hours of infection. More HPAI outbreaks have been reported between 2020-2021 than in the previous four years combined. This global trend has alarmed many producers and regulatory agencies in-context of the animal health, food, and market supply ramifications from such a fast-spreading virus. For example, between 2005 and 2020, HPAI has resulted in global death or mass depopulation of >246 million poultry, and in the two well-known peak global HPAI epidemics of 2006 and 2015, HPAI affected 25% of the world’s poultry supply. In the 2015-2016 period alone, the United States Department of Agriculture (USDA) estimated more than $1 billion in costs for the federal response and a loss of more than $1 billion in market exports.
The current pandemic of HPAI began in late 2021, and the predominant H5N1 viral subtype has been spreading through at least 54 countries. The majority of notifications in wild birds in multiple countries and regions indicates a possible introduction and spread of the virus through current wild bird migration. Europe has reported a record-setting number of HPAI outbreaks. Since December 1, 2021 alone, the European Commission’s Animal Disease Information System tallies more than 3500 outbreaks among non-poultry birds and wild birds, and more than 1700 outbreaks among backyard and commercial poultry farms. France has reported the largest number of European outbreaks (504 since February 1, 2022) predominantly centered around commercial farms in the southwest portion of the country. However, France’s agriculture ministry suspects that there has been a stabilization in outbreaks in the past few weeks owing to extensive preventive culling as well as new guidelines for a gradual risk-based approach to poultry restocking which is expected to commence in late March.
Early evidence of Highly Pathogenic Avian Influenza in commercial and backyard flocks
Though the underlying reasons behind the emergence of the current Eurasian H5N1 HPAI outbreaks (2021-2022) are unknown, genomic surveillance and epidemiologic evidence suggests that HPAI infections among poultry flocks (e.g. chicken, duck, goose, pheasant, etc) have primarily spread within Asia and Europe from infected and generally HPAI- asymptomatic wild migratory birds. While the Atlantic and Pacific oceans slow the spread of avian-borne influenza virus from Europe and Asia, H5N1 viruses began to be detected in wild birds of Newfoundland, Canada in December 2021, and across the U.S. eastern seaboard along the Atlantic flyway, by January 2022.
Since February 9th, 14th and 19th, the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the presence of HPAI in commercial turkey flocks in Dubois and Greene Counties, Indiana and in a commercial flock of broiler chickens in Fulton County, Kentucky. Additionally, positive mixed species backyard flocks have been identified in Virginia, New York, and Maine. Depopulation efforts and additional surveillance have been initiated at all commercial locations. Quarantine zones have been designated around all affected sites in order to cease movement of animals or personnel to and from affected areas. Preliminary genomic sequencing data suggests that viruses at all of these poultry sites belong to the HPAI H5N1 variant clade 18.104.22.168b, similar to the influenza A viruses detected in wild birds in the U.S. and abroad.
It is too early to determine how the initial impacts of HPAI could affect the supply and exports of poultry, especially in the midst of the ongoing COVID-19 pandemic. However, international trade partners including China, Mexico, and Korea have begun to limit importation from affected areas of the United States. With HPAI spreading at record high rates in Europe and Asia, it is expected that demand for poultry and eggs will remain robust. To help protect U.S. poultry, APHIS recently announced a significant expansion of wild bird surveillance for avian influenza in the Mississippi and Central Flyways, and enlargement of the existing Atlantic and Pacific flyway surveillance. This expansion will allow APHIS to collect 31,000 wild bird samples in 49 states. The aim of this expansion is to detect bird morbidity and mortality events that may serve as early warning systems for threats to poultry production.
Update on H5N1 Highly Pathogenic Avian Influenza (HPAI) pandemic in Minnesota
Minnesota ranks among the top poultry producers in the U.S. and is the number one turkey producer nationwide–raising roughly 45 million turkeys annually at 550 commercial turkey operations. With more than 3,000 active poultry farms, Minnesota’s poultry producers are closely monitoring cases of avian influenza that have already been identified in other states. With the anticipated northern spring migration of wild waterfowl, producers consider specific regions of Minnesota as higher-risk, including Stearns, Kandiyohi, and Meeker counties, were a large contingent of turkeys are produced in close proximity to lakes and wetlands that attract wild waterfowl potentially harboring HPAI.
Though no cases of HPAI have been reported in Minnesota, cases of wild bird HPAI have been detected in the Mississippi flyway. As a result, the Minnesota Board of Animal Health is recommending all backyard and commercial producers to begin reviewing and auditing their biosecurity practices and protocols, as well as to ensure adequate training is provided to all personnel. Mainstay biosecurity practices that are recommended include the limiting of access to barns and reducing unnecessary foot traffic to and from barns whenever possible, use of dedicated protective equipment, and performing regular equipment sanitation. HPAI H5-type viral infections in wild birds and poultry present a low health risk to the general public, and person-to-person spread of influenza A viruses are very rare. Though sporadic and occasional infections with HPAI H5N1 have been detected in people, such events tend to occur among those in close and prolonged unprotected contact with infected birds or their environment. It is therefore important that high-risk groups like poultry workers, producers, and hunters take extra contact precautions.
The University of Minnesota extension service provides resources on basics of poultry biosecurity and guidance on writing a site-specific biosecurity plan using National Poultry Improvement Plan (NPIP) audit principles. Additionally, reducing the exposure of production facilities to wild birds is paramount, and the extension site has specific recommendations on reducing the attractiveness of farms to wild birds and steps to avoid contact with dead wild birds.
CDC Avian Influenza
Bloomberg News: Expected supply-chain impacts
USDA APHIS: Current detections of HPAI
OIE 6-month report on HPAI
MDA Poultry profile