For questions/concerns about this disease in humans, please call your doctor or the Montana Department of Public Health and Human Services (DPHHS).
For questions about this disease/parasite in wildlife, please call the FWP Wildlife Health Lab at 406-577-7882.
Avian Influenza (AI) virus is a naturally occurring virus of birds. AI viruses are classified into two groups, based on the severity of disease they cause in infected poultry. Low pathogenic Avian Influenza viruses (LPAI) generally cause no clinical illness, or only minor symptoms. Highly Pathogenic Avian Influenza viruses (HPAI) are extremely infectious and fatal to poultry and some species of wild birds.
Highly Pathogenic Avian Influenza (HPAI) H5N1 was detected in Southeast Asia in 1996 and has since spread across Asia into Europe and Africa. H5N2 was detected in a Texas commercial chicken flock in 2004. Since December 2014, highly pathogenic avian influenza A H5N2, H5N8 viruses and a newly identified H5N1 virus have been reported in the Pacific, Central, and Mississippi Flyways of North America. These viruses have been detected in wild birds, captive wild birds, and poultry flocks. The first known case of HPAI (H5N2) in Montana was detected in a captive Gyrfalcon in March 2015. Shortly after the virus was detected in the gyrfalcon, H5N2 was detected in a back yard poultry flock in Judith Basin County.
In January 2022, the first HPAI H5N1 virus (clade 184.108.40.206b) infection in wild birds in the United States since 2016 was reported by USDA/APHIS. Additional detections in wild birds were subsequently reported. In February 2022, USDA/APHIS announced an HPAI H5N1 outbreak in turkeys in a commercial poultry facility, marking the first HPAI detection in commercial poultry in the United States since 2020. By early April 2022, Montana had its first detection in domestic poultry flocks. Montana was the 25th state to detect the virus in poultry in 2022. The first detection of the virus in wild birds in Montana occurred in mid-April 2022.
As of 10/28/22, HPAI H5N1 (220.127.116.11) has been documented in wild birds in 20 Montana counties.
For current information on HPAI in the United States, you can access the CDC Avian Influenza Situation Summary at this link: https://www.cdc.gov/flu/avianflu/avian-flu-summary.htm
Domestic poultry such as turkeys and chickens are very susceptible to infection with Highly Pathogenic Avian Influenza (HPAI). Wild waterfowl such as ducks and geese may carry the virus without exhibiting signs of illness; however, some infected waterfowl do develop disease. Several Canada geese have developed symptoms and died from infection with HPAI. Birds of prey (falcons, hawks, eagles) also appear to be very susceptible to disease and may become infected by consuming infected waterfowl. Wild gallinaceous birds such as turkeys, quail, and sage grouse, and scavengers such as ravens, crows and gulls may be susceptible in some cases. The detection of HPAI virus in a chickadee in Minnesota indicates that a wide variety of bird species may be vulnerable to the HPAI viruses recently detected in the United States.
HPAI was detected in one captive gyrfalcon in Montana in 2015. During the 2022 outbreak, HPAI was the documented cause of death in a variety of wild bird species including bald eagles, great horned owls, red-tailed hawks, turkey vultures, Canada geese, snow geese, great blue heron, white pelican, wild turkey, common raven, trumpeter swan, and wood duck.
HPAI has also been detected in a small number of wild mammals in some U.S. states and Canada during the 2022 outbreak. The virus has been detected in red foxes, skunks, raccoons, and a coyote pup. The first detection of HPAI in a wild mammal in Montana was in a striped skunk that died in October 2022.
The virus is shed in oral and nasal secretions and feces of infected birds, and can be spread via aerosol, direct contact with infected birds, contaminated drinking water, or fomites (any inanimate object or substance capable of carrying infectious organisms) (Western, 2009). Raptors and wild mammals are usually infected by consuming infected bird carcasses. The role of migratory birds in the spread of Highly Pathogenic Avian Influenza is still being investigated.
HPAI may cause significant disease in wild birds, depending on the specific virus and the host species. In some cases, birds can be infected and actively shedding virus without exhibiting signs of disease (Stitt, 2011).
Symptomatic birds may exhibit any number of symptoms including respiratory distress, weakness, neurologic impairment (lack of coordination), seizures, and death, but are usually simply found dead. HPAI outbreaks are often characterized by the following:
Mortality events involving waterfowl (ducks, geese, or swans) or other water birds (loons, grebes, coots, shorebirds, or wading birds such as egrets, herons, or cranes)
More than 5 dead birds at one time in one location
Mortality events involving individual raptors or other avian scavengers (ravens, crows, or gulls), particularly those observed near locations with on-going water-bird mortality
Mortality events involving any wild bird species that:
exhibit neurological signs, seizures, acute death, respiratory distress
are found near facilities harboring domestic birds (or wild/captive) in which HPAI has been detected
Wild mammals such as foxes, skunks and raccoons may simply be found dead. Symptoms in live animals may include lethargy, weakness, incoordination, tremors, seizures, and abnormal behavior such as lack of fear of humans.
Different HPAI viruses have different levels of infectivity for humans and cause symptoms of varying degrees of severity. Human infections with HPAI have generally occurred after close and prolonged contact with infected birds or the excretions/secretions of infected birds. Some HPAI viruses have infected people in other countries and caused serious illness and death in some cases. The H5N1 avian flu viruses that are circulating in wild birds and poultry in much of the world in 2022 are genetically different from earlier versions of the virus and emerged to become the predominant subtype of HPAI H5 in the fall of 2021. In contrast to previous H5N1 viruses, which still circulate to a lesser extent in several countries, at this time, only two human cases with current H5N1 bird flu viruses have been reported during the 2021-22 outbreak.
One infection occurred in December 2021 in a person in the United Kingdom who did not have any symptoms and who raised birds that became infected with H5N1 bird flu viruses.
A second human case was reported in the United States in April 2022 in a person who was involved in culling (depopulating) of H5N1 virus-infected poultry. The person reported fatigue and has recovered.
Although the CDC considers risk to human health from the strains of AI found in Montana to be low, Montanans should take precautions (see precautions section) when handling game birds or any sick or dead bird they find.
While there is no evidence that any human cases of avian influenza have ever been acquired by eating properly cooked poultry products (CDC), bird hunters should follow these simple precautions when processing or handling wild game:
Do not harvest or handle wild birds that are obviously sick or found dead.
Wear disposable latex or rubber gloves while cleaning game or cleaning bird feeders.
Clean bird carcasses outdoors or in a well-ventilated area
Do not eat, drink or smoke while cleaning game.
People and equipment that have been in contact with wild game birds should avoid contact with back yard poultry flocks.
Wash hands with soap and water or alcohol wipes 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 percent solution of chlorine bleach—one part chlorine bleach to 10 parts water.
Separate raw meat, and anything it touches, from cooked or ready-to-eat foods to avoid contamination.
Cook game meat thoroughly to an internal temperature of at least 165°F.
Investigation of morbidity/mortality events in wild birds or other species offers wildlife professionals the best opportunity to detect the highly pathogenic avian influenza virus. The public is encouraged to report unusual or unexplained cases of sickness and/or death by calling their local wildlife biologist or the wildlife health lab in Bozeman.
Wildlife Health Lab: 406-577-7880 or 406-577-7882
Wildlife health staff will work with local wildlife staff to determine the appropriate response to these reports.
Whenever possible, avoid contact with sick or dead wildlife. Even if a bird is not suspected to have died from a contagious disease, gloves should always be worn if a dead animal must be handled for disposal.
While there is no evidence that any human cases of avian influenza have ever been acquired by eating properly cooked poultry products or upland game bird meat, (CDC), all game meat should be cooked well to an internal temperature of at least 165°F. If you harvest an animal and are unsure whether it is safe to eat, contact your local FWP staff for guidance soon after the animal is harvested.
Stitt, Tyler. 2011. Diseases You Can Get From Wildlife - A Field-guide for Hunters, Trappers, Anglers and Biologists. British Columbia Ministry of the Environment.
Western Wildlife Disease Workshop Notebook. 2009. Southeastern Cooperative Wildlife Disease Study. College of Veterinary Medicine, University of Georgia.