Highly pathogenic avian influenza (HPAI) has not been featured as prominently in the news lately as it was in winter. Luckily, cases in Illinois have been on the decline this spring. This was expected, as the influenza virus is less stable and survives poorly in warmer and drier environments, and wild birds have completed their migrations and settled into their nesting and breeding season, leaving less opportunities for bird-to-bird and bird-to-livestock viral transmission.
Cases may be diminishing, but veterinarians should still be familiar with H5N1 and be on the alert for additional cases, particularly once we enter next fall and winter. In Illinois, H5N1 has been detected in poultry, wild birds, a wild opossum, and animals in zoologic collections.
At our Wildlife Medical Clinic last winter, we tested over 60 birds, almost every wild bird admitted in 2025, and documented H5N1 in two Canada geese, a red-shouldered hawk, and a great horned owl from Urbana, Champaign, Effingham, and Tuscola, respectively. Our most recent HPAI positive case was admitted on March 24.
The Illinois Department of Public Health (IDPH) has created an H5N1 Outbreaks Dashboard (1) to help keep the public apprised of the current situation in the state. As of early May, no human or dairy cattle H5N1 cases have been detected in Illinois. In other states, the virus has been detected in humans, dairy cattle, domestic cats, and huge variety of wild mammals, including foxes, raccoons, bobcats, and marine mammals.
IDPH has a number of helpful resources on their H5N1 Toolkit page (2), including helpful information for veterinarians, animal control agencies, pet owners, animal exhibitors, and wildlife rehabilitators. If veterinarians want to test an animal for HPAI, they can submit samples to the college’s Veterinary Diagnostic Laboratory. Instructions on how to submit a sample can be found at vdl.vetmed.illinois.edu/vdl-news/741382.
Following are questions commonly asked by the public that veterinary practitioners should be prepared to answer.
What kinds of contacts can lead to infection in pets and humans?
Pets may become infected with HPAI if they eat dead infected birds, eat raw meat from infected birds, or drink unpasteurized milk from infected cows. Some raw pet foods have been linked to HPAI infection and deaths in house cats (3). Other routes of transmission, such as inhalation or ingestion of aerosolized secretions or feces from infected birds, are also possible.
In humans, most HPAI infections have occurred from unprotected direct contact with infected animals — usually poultry or cattle — or surfaces contaminated with feces or respiratory secretions from infected animals. The virus can enter through a person’s eyes, nose, or mouth or via inhalation.
No infections have been reported from ingestion of properly cooked poultry or pasteurized milk, but improper handling of raw poultry products or ingestion of undercooked meat or unpasteurized milk could result in infection in humans as well as pets.
Cats, dogs and other pets are known to find and play with dead or injured wildlife when outside. How do we curb their natural inclinations to keep them safe from HPAI?
It is recommended to always keep cats indoors. Cats, dogs, and other pets that do spend some time outdoors should remain leashed and closely monitored to keep them away from wildlife and poultry.
Are all dead birds or animals a risk, or only waterbirds?
Unfortunately, all dead animal carcasses have the potential to transmit HPAI. Waterbirds are the most affected species, and they have the potential to transmit the virus without showing clinical signs, but a huge variety of wild and domestic bird and mammal (4) species have died from HPAI.
How do people with backyard flocks prevent infection in their animals?
People with backyard flocks should keep their birds fully enclosed, with a solid roof covering them, to keep their poultry away from wild birds and their droppings during HPAI outbreaks. All feed, drinking water, equipment and other supplies should be stored out of reach of wild birds and rodents. The entire coop and run should be rodent proof, as mice and rats have also been shown to transmit avian influenza.
Hardware cloth with 1/4-inch openings can be used around the entire perimeter and floor of the run or buried several inches underground to prevent rodents from burrowing, and 1/4-inch hardware cloth can also be used to seal up any small openings in the coup or near doors.
Owners or caretakers of backyard poultry should not wear clothes or shoes with their birds that they have worn while caring for other birds or that they have worn while hiking or walking in locations where waterfowl are present. Ideally, bird owners should have footwear they use only around their own birds. Shoe covers can also be used. During HPAI outbreaks, do not allow human or animal visitors to your flock.
If you are concerned about HPAI in your flock, call your veterinarian first before bringing your birds to the clinic. If you have any suspicious deaths in your flock, particularly if multiple animals are sick or deceased, contact your veterinarian so they can report the event to the state animal health official, if applicable.
Avoid handling dead animals, but if you need to handle any carcasses, be sure to use appropriate personal protective equipment, including goggles, an N95 mask, nitrile gloves, shoe covers, and disposable coveralls. Double bag all carcasses and potentially contaminated materials and disinfect the outside of the bag with an antimicrobial effective against avian influenza (5).
Are some animals more susceptible than others?
Yes, there appears to be a range of susceptibility to this current strain of H5N1 among different species. Besides water- birds, the next most frequently seen wild birds with HPAI-related morbidity and mortality are crows and raptors, but any bird can become sick with avian influenza.
Clinical signs in birds we see most frequently are cloudy eyes, a sign of corneal edema, and neurologic signs like tremors, weakness, incoordination, inability to stand, and seizures, but other vague, non-specific signs of illness can occur, or the animal may die suddenly without observed clinical signs.
The clinical signs of avian influenza in any species can mimic those of many other diseases, so there’s no way to know for sure an animal has avian influenza without laboratory diagnostics. As mentioned, waterfowl such as ducks and geese can contract and spread the disease without getting sick themselves.
Wild carnivores, such as foxes, bobcats and other wild felines, skunks, fishers, mink, and even marine mammals such as seals have all been documented to get sick and die from avian influenza.
Felines, both wild and domestic, appear particularly susceptible to severe disease and death from this virus. Tragically, a wildlife sanctuary in Washington lost over half of their big cats to HPAI in December 2024.
In the past year, HPAI has also been documented in dairy cows in 17 states. The virus appears to be able to circulate between cows, sometimes without illness in the cows, and from cows to humans, which was the first likely mammal-to-human spread of this virus.
The first detections in pigs in the U.S. occurred in October 2024. Horses in the U.S. have not been documented with HPAI, but there is recently documented evidence of infections in horses in Mongolia.
Avian influenza cases in humans have been rare and largely mild. The Louisiana Department of Health announced the first H5N1-related human death in the U.S. but note that person was over the age of 65 and had underlying medical conditions. There remains no evidence of human-to-human transmission of avian influenza in the United States to date.
What precautions are you taking at the University of Illinois Wildlife Medical Clinic?
This past winter, under the direction of the Illinois Department of Natural Resources (IDNR) and IDPH, the Wildlife Medical Clinic was limited in our ability to accept waterfowl patients and had very stringent biosecurity and HPAI testing procedures.
We are happy to say that we are now able to receive and care for all native species (except for bats and skunks, per IDNR, due to their heightened risk of carrying rabies). We are still taking precautions, including the use of PPE and careful disinfection protocols, to help protect our patients, resident ambassador animals, volunteers, and staff, and will continue to test cases with clinical signs consistent with HPAI.
We are still encouraging the public to avoid contact with wildlife displaying signs of illness consistent with HPAI, and to report bird mortality events — the death of five or more birds — to IDNR district wildlife biologists (6). Reports can also be made to the U.S. Department of Agriculture Wildlife Services at 1-866-487-3297.
References
- H5N1 Outbreaks Dashboard. https://dph.illinois.gov/topics-services/diseases-and-conditions/respiratory-disease/diseases/influenza/h5n1/toolkit/outbreaks-dashboard.html
- H5N1 Toolkit. https://dph.illinois.gov/topics-services/diseases-and-conditions/respiratory-disease/diseases/influenza/h5n1/toolkit.html
- County of Los Angeles Public Health. http://publichealth.lacounty.gov/phcommon/public/media/mediapubhpdetail.cfm?prid=4923
- Animal and Plant Health Inspection Service. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/mammals
- Environmental Protection Agency antimicrobial list. https://www.epa.gov/pesticide-registration/epas-registered-antimicrobial-products-effective-against-avian-influenza
- Illinois Department of Natural Resources. https://wildlifeillinois.org/idnr-district-wildlife-biologist/
By Stephany Lewis, DVM, CWR, DABVP (Avian Practice)
Revised Wildlife Intake Procedures after HPAI Procedures after HPAI Threat Level Reduced
According to the Illinois Department of Natural Resources and Illinois Department of Public Health, in conjunction with our screening, the risk of Highly Pathogenic Avian Influenza exposure has minimized with seasonal change. Biosecurity protocols at the Veterinary Teaching Hospital have changed to reflect the reduced threat level.
Weekdays, 6 p.m. to 7:30 a.m., and Saturday 7:30 a.m. through Monday 7:30 a.m.: Wildlife will be accepted via the Small Animal Clinic emergency service and transferred to the Wildlife Medical Clinic in the morning.
Weekdays, 7:30 a.m. to 6 p.m.: Wildlife will be accepted through the Wildlife Medical Clinic at the Dr. John Coyne South Clinic.
