Avian Influenza

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What is Avian Influenza?

Avian Influenza (AI) is a type A influenza respiratory virus naturally found in certain waterfowl, gulls, and shorebird species. AI refers to the disease caused by infection with avian influenza Type A viruses. These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species, but rarely infect humans. Avian influenza can be spread through saliva, nasal secretions, and feces directly from an infected bird or through contaminated surfaces.


Highly Pathogenic Avian Influenza (HPAI), which includes strains such as H5N1 and H5, is more concerning than the less virulent Low Pathogenic Avian Influenza (LPAI) strains. This is because the high pathogenic strains have a greater likelihood of spreading and mutating between wild and domestic populations, are more likely to produce disease, and are often fatal. Wild bird strains H5 and H7 AIVs can spill over into domestic poultry where they can exist as low pathogenic viruses or mutate to high pathogenicity, which can cause high mortality. LPAI is more frequently found in wild birds and domestic poultry and typically causes no to minimal signs of illness.

It’s important to note that avian influenza detections in birds do not present an immediate public health concern. A human case of avian influenza was detected in a commercial poultry worker in the United States in April of 2022. This was a situation in a confined space with thousands of poultry where ventilation is challenging. The worker experienced mild flu-like symptoms and recovered. For more information on the symptoms and the spread of avian flu viruses to humans, please visit the Maine CDC website.

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What are the signs and symptoms of HPAI?

Susceptible birds can become infected with the virus through contact with saliva, nasal secretions, or feces of an infected bird, as well as surfaces contaminated with the virus. While some individuals may appear asymptomatic, outward symptoms of the HPAI can range from lethargy to severe neurological impairment, including:

  • Circling/lack of coordination
  • Tremors/seizures
  • Twisted neck
  • Decrease in egg production
  • Swelling of head or eyelids
  • Nasal discharge, cough, sneezing, and diarrhea
  • Sudden death

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What is the status of HPAI in Maine?

HPAI H5N1 has now been confirmed in 47 U.S. states and 11 Canadian provinces. Cases have occurred in commercial poultry, backyard poultry flocks, 104 species of wild birds, eight species of scavenging mammals, and two species of seals. As of November 2022, eleven species of wild birds have tested positive for HPAI in Maine including arctic tern, common tern, bald eagle, Canada goose, common eider, mallard, American black duck, double-crested cormorant, great black-backed gull, herring gull, and peregrine falcon.

For more information on surveillance in Maine and Nationally you can visit USDA WS National Wildlife Disease Program’s dashboard and view detections by county on a map.

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What animals can be affected?

While most wild birds such as ducks, gulls, and shorebirds can carry and spread the disease, they may not exhibit any signs of illness. HPAI is well known to impact and kill domestic poultry such as chickens, turkeys, ducks, and geese. Additionally, there have been predatory birds such as bald eagles and peregrine falcons that have been tested for and died from avian influenza here in Maine.

Cases of the avian influenza virus jumping from avian species to mammals have recently been documented in gray and harbor seals off the coast of Maine, black bear in Quebec, and red fox kits in Michigan, Minnesota, Iowa, and Wisconsin.

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What can you do to prevent the spread of HPAI in Maine?

Avoid and mitigate the spread of avian influenza by practicing proper hygiene and maintaining good biosecurity.

  • Try not to walk in fields or other areas where you would get waste on your clothing or boots. If there is a chance you walked in bird waste, thoroughly clean and sanitize your gear before going to other areas.
  • Anyone feeding birds should do so with care. While many birdfeeder species may not be prime carriers, supplemental feed that could attract wild ducks, geese and turkeys could carry HPAI, which can be particularly concerning for homeowners that have domestic poultry.
  • Contain and separate domestic birds from wild birds to prevent possible spread. For example, if you have a pond that your domestic poultry uses, try to prevent wild birds from using the same area with netting or fencing.

For anyone with pets (dogs/cats) that may come into contact with possibly infected bird species, contact your veterinarian if your pet becomes symptomatic. Precautions should be taken to limit exposure to birds with abnormal behavior.

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What to do if you find sick, injured, or dead birds

Contact a regional wildlife biologist to report wild birds when:

  • Birds are showing signs of illness or died soon after
  • Dead birds are found in near domestic poultry
  • You find dead waterfowl, birds of prey, shorebirds, gulls, or other seabirds

MDIFW recommends avoiding contact with sick and dead wild birds. However, if a dead bird is found on one’s property, it can be removed at the property owner’s discretion after contacting a regional wildlife biologist. If removing a dead bird, we recommend the following precautions:

  • Wear a disposable mask
  • Wear disposable gloves
  • Double-bag the bird; place the bird within the inner bag and knot or tape the bag closed
  • Remove gloves and mask; place inside the outer bag and knot or tape the outer bag closed
  • Place the double-bagged bird in the trash
  • Wash hands with soap and water (or use sanitizer if unable to wash hands)

Reporting these incidents is supportive of our statewide surveillance efforts and we are particularly concerned with reports of three or more dead birds in a localized area.

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Consideration for hunters

Avian influenza does not present a food safety risk if wild game, poultry and eggs are handled and cooked properly. We encourage hunters to practice safe handling of harvested game. 

  • Do not harvest game that appear obviously sick or found dead 
  • Process game outdoors or in a well-ventilated area 
  • Wear gloves and wash hands before and after handling the carcass 
  • Disinfect all equipment that comes into contact with dead game (e.g., knives, surfaces) 
  • Refrain from eating, drinking, smoking, and touching your eyes during processing 
  • Cook meat thoroughly 
  • For those hunting in areas of potential exposure to bird droppings on the ground, such as agricultural fields or wetland shores, disinfect boots before moving to another area by first rinsing dirt and grime with water. Then spray with a mix of one part household bleach (typically listed as 5-6% on the label) to nine parts water. 

Attention Sea Duck Hunters: Maine and our partners in the Atlantic flyway are asking hunters to refrain from shooting female and immature eiders this waterfowl hunting season.

Male (left) and female eider pair. Photo by Kirk Rogers

Maine and our partners in the Atlantic flyway are asking hunters to refrain from shooting female and immature eiders this waterfowl hunting season. Male eiders are readily distinguishable from female and immature males, as the males’s striking white and black plumage is in stark contrast to the brown of female and juvenile eiders.

Due to an outbreak of Highly Pathogenic Avian Influenza (HPAI) in the St Lawrence waterway in Canada, an estimated 5-15% of nesting eider females died this year, negatively impacting the eider population, possibly for several years.

Many of the eiders from the St. Lawrence waterway migrate south to winter in US waters along the Northeast coast, coinciding with Maine’s Coastal Zone waterfowl season.

Due to their small clutch size, few eider ducklings are hatched each year and survival of those birds are low due to factors such as gull predation and the challenges of our ocean waters. Loss to Avian Influenza compounds those problems.

The daily bag limit for eiders in Atlantic Flyway states is currently limited to no more than 3 of which only 1 can be a hen. This season, we are asking Maine hunters and sea duck guides to support Canada’s efforts by voluntarily refraining from harvest of “brown” birds.

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Consideration for licensed wildlife rehabilitators

Highly Pathogenic Avian Influenza (HPAI) virus has been detected in multiple species of wild birds in North America since December 2021. HPAI is highly contagious among birds, and can be deadly, especially in domestic poultry. HPAI was also detected in wild seals along coastal Atlantic states, red fox in more western states and a black bear in Canada. HPAI is a type A influenza virus typically spread by wild aquatic birds including waterfowl, shorebirds and gulls but can infect other bird species such as birds of prey. 

More recently in Maine, through surveillance during annual duck banding efforts in early September 2022, three mallards tested positive for HPAI. This is a good reminder that HPAI is still in the environment and continued biosecurity and caution should continue. 

Excerpts from “Association of Fish & Wildlife Agencies Guidance for State Wildlife Agencies to Reduce the Risk of Highly Pathogenic Avian Influenza Transmission in Wildlife Rehabilitation Facilities”  

  • Wildlife rehabilitation facilities may be at risk for receiving infected species and incidentally promoting transmission because of close contact among species and caregivers. This could result in spillover to species that might otherwise not be exposed in a natural setting. The wide breadth of species that can be affected and the variation in clinical signs make it difficult to triage high-risk HPAI candidates. Wildlife rehabilitators need to be aware that intake of infected animals may put other patients and educational animals at risk. 
  • Most HPAI infections have been detected in waterfowl and other aquatic birds, raptors, and scavengers (gulls, ravens, crows), but all avian species should be considered susceptible. 
  • Avian species and individual animals may be infected with HPAI without showing clinical signs (asymptomatic). Thus, caution should be given regarding basing a preventative program on clinical signs. When present, clinical signs are not specific to HPAI and could be due to other causes. Clinical signs of HPAI in birds are highly variable, however, more common clinical signs may include one or more of the following: 
  • Respiratory (sneezing, coughing, ocular & nasal discharge, periorbital edema) 
  • Dermatologic (limb edema, patchy erythema – more common in poultry) 
  • Neurologic (abnormal position of head or neck, ataxia, circling) 
  • Gastro-intestinal (diarrhea, green discoloration to feces) 
  • Weakness, lethargy, depression 
  • Sudden death 
  • The virus is shed at high levels through all respiratory secretions, saliva, and feces. It can also remain infective in cold and wet environments and remain infective and stable in water and feces depending on temperature and humidity. 
  • Presently, humans appear to be at lower risk for infection with the current HPAI strain, although individuals who have frequent close contact with wild birds, especially waterfowl, may be at higher risk for exposure. 

Considerations for animals suspected of having HPAI:

  • If an incoming patient is suspected to have HPAI it should be separated from other animals in a designated area. 
  • Full exam should be done in the designated area. 
  • Staff handling/examining suspects should wear PPE: gloves, mask, and gown. 
  • Suspects should stay in the designated area for a few days to monitor. 
  • Remove PPE after handling and sanitize (spray and wipe with a mix of one part household bleach (typically listed as 5-6% on the label) to nine parts water) 
  • Instruments, feeding tubes, bowls, etc. should be placed in a plastic bin and soaked in iodine solution in the designated area. Once soaked for 10 minutes, they can be brought in and cleaned, and placed back in designated area. 
  • Place reusable towels in separate bin. Soak in bleach solution before washing. 
  • Launder separately from other towels. 
  • Wash hands after handling animals and materials. 

Additional guidelines for staff members that have pet birds or poultry at home:

  • Keep a pair of shoes onsite that is worn only at work 
  • Wear clothing (at least an outer layer) that is worn only onsite 
  • Change clothes immediately upon returning home 
  • Keep work clothing in a plastic bag until laundered; launder separately from at-home  
  • Shower as soon as possible upon arriving home (or at least wash hands and face)

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To learn more about the impacts of avian influenza on domestic poultry, please visit The Maine Department of Agriculture, Conservation, and Forestry.

To learn more about avian influenza and human health, please visit the Maine Centers for Disease Control.

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