Avian influenza: common questions and answers
Originally published June 16, 2022, this blog has been updated as recently as Mar. 4, 2024 to reflect positive cases of highly pathogenic avian influenza as information becomes available. Please report sick or dead wild birds suspected of having avian influenza
In February of 2024, a resident of Kettle Falls in northeast Washington’s Stevens County reported three dead striped skunks on their property. A fourth dead skunk was found later. Testing of the carcasses showed the skunks were positive for the highly pathogenic avian influenza (HPAI) H5N1 strain.
This is not the first case of mammals testing positive for HPAI H5N1 either nationwide or in Washington. Since July of 22 several cases have been confirmed in Washington including:
- In August of 2023, NOAA Fisheries confirmed that five adult harbor seals in Puget Sound tested positive for the HPAI H5N1 strain. It is believed that the virus was transmitted to the seals on Rat Island and Marrowstone Island from Caspian terns involved in an HPAI outbreak that resulted in the death of approximately 1,700 birds. This marked the first incidence of HPAI in marine mammals on the West Coast.
- In January 2023, a bobcat from northeast Washington tested positive for HPAI.
- Three raccoons (one on Camano Island, one in Spokane County, and one in the Tri Cities area) tested positive in 2022.
While the spread of HPAI from birds to mammals is alarming to some, it is not surprising. At this time, WDFW Wildlife Veterinarians are not concerned about (wild) mammal to mammal transmission as there is no evidence to support that this is occurring.
Following are answers to common questions regarding H5N1 HPAI, the impact to wildlife, and the potential spread to domestic animals and humans, as well as what you can do to protect yourself and domestic animals:
What is HPAI?
Avian influenza, commonly known as bird flu, refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses. These viruses occur naturally among wild aquatic birds worldwide and can infect poultry and other bird and animal species. Wild aquatic birds include ducks, geese, swans, gulls and terns, and shorebirds
Avian influenza A viruses are very contagious among birds through saliva, nasal secretions, feces, and contaminated surfaces.
How is H5N1 HPAI different than previous HPAI outbreaks in North America?
The current strain of HPAI (officially known as H5N1 2.3.4.4b) circulating in North America, and much of the world, is different in that it has remained on the landscape, primarily in wild birds. Previous strains have run their course and mostly disappeared when warmer weather dispersed birds from congregating together to feed as they do in winter.
Is it common for other animals, besides birds, to catch HPAI?
In addition to the cases above of HPAI spreading to mammals in Washington, it has also been detected in red foxes, striped skunks, and bobcats in other states in North America. However, Washington had the first detections of the H5 2.3.4.4 virus in raccoons in North America, and the raccoons were the first detection of HPAI in a mammal in Washington state.
According to the Centers for Disease Control and Prevention, as HPAI viruses continue to evolve, other mammals may become infected.
Does H5N1 HPAI have a negative impact on wildlife populations?
The impact(s) of H5N1 HPAI on wild bird populations is complex. In most instances, though mortality may seem high, the overall impact on the population is miniscule, such as with waterfowl. However, in some rare cases the population level impact may be extensive. An example of this is the Caspian Tern mortality event in Jefferson County in the summer of 2023. That outbreak resulted in a mortality rate of approximately 54% of the breeding adults at that single tern colony. WDFW estimates that the impact of H5N1 HPAI on Caspian Terns in the Pacific Flyway was approximately 14% mortality rate in the summer of 2023.
In South America, the mortality rate in wild birds, primarily colonially nesting seabirds, has been catastrophic, with over 500,000 seabirds killed by H5N1. Extensive mortality has also been observed in marine mammals (over 50,000 animals) in South America. The long-term impacts of HPAI on populations remains to be seen. A December 2023 report from the World Organisation for Animal Health (WHOA) and the Food and Agriculture Organization of the United Nation’s Network Of Expertise on Animal Influenza (Offlu) highlights the mortalities associated with HPAI H5N1 in South America.
What can be done to prevent the spread of HPAI to other wildlife species?
Avoid handling sick or dead birds or other wildlife and keep pets from scavenging or interacting with dead animals. Practices that cause birds to congregate in large numbers, such as feeding waterfowl, should also be avoided.
Waterfowl and other bird hunters or people who work in areas that birds frequent should ensure that all equipment (boots, clothes, vehicles, firearms) are cleaned and disinfected to prevent spreading diseases from one area to another.
Reporting sick or dead birds or other wildlife to WDFW’s online reporting tool can help the Department monitor the spread of viruses and notify members of the public to take precautions.
If I encounter sick or dead birds or other wildlife, what is the best way to dispose of carcasses to keep other animals from scavenging on them?
If you must move a dead bird or animal to prevent pet contact, wear gloves, double-bag it, and place it deep into the garbage where scavenging cats, dogs, or raccoons can’t find it. You can also bury or incinerate carcasses.
What can be done to treat wildlife with HPAI? Is there a treatment or vaccine?
Unfortunately, treatment is not an option for wild species. Most birds or mammals that become ill with HPAI will die from the infection.
If wild animals can catch HPAI, can my domestic cats and dogs?
Given what is currently known about this strain of HPAI, this is unlikely. Still, appropriate action should be taken to reduce the potential risk to mammals such as cats and dogs, including not allowing domestic animals to scavenge sick/dead birds or other wildlife, or even interact with sick wildlife. In addition, HPAI can infect domestic chickens, ducks, turkey. If sick or dead poultry are observed, please report to the Washington Department of Agriculture.
Can HPAI transfer to humans?
Bird flu viruses are not easily transmissible from birds to people, but without proper hygiene, or if in prolonged contact with a sick bird, the risk increases and the virus can spread to humans. While it is extremely unlikely that hunters or people feeding wild birds could contract bird flu, the following common-sense precautions are recommended to reduce the risk of contracting any wildlife disease:
· Wear disposable gloves when cleaning harvested birds or cleaning bird feeders.
· Do not harvest or handle wild birds that are obviously sick or found dead.
· Do not eat, drink, or smoke while cleaning game.
· Wash hands with soap and water or use alcohol hand sanitizer immediately after handling game or cleaning bird feeders.
· Wash tools and work surfaces used to clean game birds with soap and water, then disinfect with a 10% solution of chlorine bleach.
· Separate raw meat, and anything it touches, from cooked or ready-to-eat foods to avoid contamination.
· Cook game birds thoroughly. Meat should reach an internal temperature of 155 to 165 degrees Fahrenheit to kill disease organisms and parasites. Freezing does not kill the HPAI virus.
If you experience flu-like symptoms following contact with sick or dead wild birds or have concerns about potential exposure to infected birds, contact your local health department. They can provide public health recommendations and guidance on symptom monitoring and testing of people exposed to avian influenza.
Additional animal and human health and safety information regarding avian influenza is on the U.S. Department of Agriculture Animal and Plant Health Inspection Service website.
How long can the HPAI virus survive in the environment?
In the right conditions, it can survive from day to weeks but the most likely way for the virus to transfer to other birds or mammals is sick or dead birds, not from the environment.
What should I do if I see a sick or dead bird or other wild animal?
Report sick or dead birds or other wildlife to WDFW’s online reporting tool can help the Department monitor the spread of viruses.
