Although the highly pathogenic avian influenza (HPAI) has been spreading globally for almost four years, the recent outbreak of the new type A H5N1 variant has created cause for concern due to its rapid spread amongst wild and migratory bird populations, as well as several animal species, including humans.
In fact, the American Veterinary Medical Association notes that “experts [are worried] that H5N1 will eventually mutate into a lethal strain capable of human-to-human transmission, setting off another pandemic.”
While the Centers for Disease Control and Prevention assess the current risk to human health as significantly low, a research article published in Science found that it may only take one more mutation for the virus to switch host receptor recognition specificity, making humans increasingly susceptible to infection.
The bird flu has not only been affecting wild migratory water birds and domestic poultry, but the virus has also been spreading to other wild animals such as cattle (especially dairy cows), pigs, juvenile goats, mountain lions, bobcats, seals, bears, foxes, skunks, farmed mink, as well as stray or domestic animals such as cats and dogs and zoo animals such as tigers and leopards.
In March 2024, an outbreak of avian influenza type A (H5N1) was confirmed in dairy cattle in California, Colorado, Idaho, Michigan, Texas, Iowa, Utah, Minnesota, New Mexico, South Dakota, Kansas, Oklahoma, Nevada, North Carolina, Ohio and Wyoming. The AVMA indicates that while HPAI is associated with high mortality rates in birds, only 2% of infected cattle have died from the virus, which is relatively low considering it spreads from cow-to-cow. Common signs for farmers to look out for are low appetite, reduced milk production and abnormal appearance of milk that is thickened and/or discolored.
Additionally, cats of all kinds are particularly susceptible to the virus, which often results in death. The severe illness that the bird flu causes can include neurological signs, respiratory signs or liver disease that can rapidly progress to death.
Cats and dogs (although much less likely) can potentially become infected if they eat sick or dead infected birds, drink unpasteurized milk or cream from infected cows or eat undercooked or raw meat.
People can also become infected through exposure to infected animals, which is usually the result of close or prolonged exposure to infected poultry or dairy cows. Person-to-person spread of the virus has not been reported and cases have been generally mild.
In 2024, the CDC confirmed 66 infections in people in the United States. Of these, 23 cases were associated with exposure to infected poultry, 40 were associated with exposure to infected dairy cows, one was associated with “other” animal exposure and two sources of infection remain unknown. Moreover, the number of cases associated with each state include 37 cases in California, 10 cases in Colorado, one case in Iowa, one case in Louisiana, two cases in Michigan, one case in Missouri, one case in Oregon, one case in Texas, 11 cases in Washington and one case in Wisconsin.
As of Monday, Jan. 6 the 65-year-old individual hospitalized due to severe H5N1 bird flu in Louisiana has died, marking the first and only human case of the virus in the state and the first death in the United States connected with avian influenza. According to the Louisiana Department of Health, the individual was reported to have underlying medical conditions and contracted H5N1 after exposure to a combination of non-commercial backyard flock and wild birds.
A press release from the CDC stated, “While tragic, a death from H5N1 bird flu in the United States is not unexpected because of the known potential for infection with these viruses to cause severe illness and death.”
Additionally, a report by the World Health Organization identified that there have been over 950 confirmed human cases of H5N1 bird flu outside the United States between 2003-2024, and about half of those have resulted in death.
According to the CDC’s press release, they have “carefully studied the available information about the person who died in Louisiana and continue to assess that the risk to the general public remains low. Most importantly, no person-to-person transmission spread has been identified.”
So, just how close to home is this threat?
On April 15, 2022, the state’s first positive case of HPAI in domestic poultry was confirmed in a flock of commercial layer chickens on a Lancaster County poultry farm. Then, in April through July 2023, six cases were confirmed in red foxes including five in Huntington County and one in Northampton County as reported by the U.S. Department of Agriculture. Since May 2022, no other mammalian species have been detected in Pennsylvania.
Recently, the deaths of 200 snow geese in Lower Nazareth Township and Upper Macungie Township are suspected to be caused by avian influenza. Preliminary testing found the presence of the virus, but the U.S. Department of Agriculture will need to confirm these results.
Excluding the Lehigh Valley outbreak, the USDA reports that there have been 111 confirmed flocks infected with HPAI, which includes 61 commercial flocks, 50 backyard flocks and 10.16 million birds affected mostly in California (state of emergency declared on Dec. 18), South Dakota, Iowa, Michigan, Minnesota, Nebraska, Kansas, Oklahoma, Missouri, Arkansas, Wisconsin, Illinois, Mississippi, Alabama, South Carolina and Ohio.
According to the AVMA, the USDA is currently conducting field trials of a handful of HPAI vaccines for poultry and dairy cattle. In the meantime, the USDA, U.S. Food and Drug Administration and CDC state they have “no concerns about the safety of the commercial milk supply because milk from impacted animals is being diverted or destroyed, so it does not enter the human food supply.”
However, the FDA strongly encourages that any milk diverted for feeding calves be heat treated to kill harmful bacteria or viruses before feeding. People are also advised not to drink raw milk or eat raw milk-based cheese and to properly handle and cook meat to an internal temperature of at least 165 degrees Fahrenheit, which includes any meat used to feed pets.
Signs to watch out for in backyard flocks and pet birds that may be infected include sudden death with no prior signs, low energy or appetite, purple discoloration or swelling of various body parts, reduced egg production or soft-shelled/misshapen eggs, nasal discharge, coughing or sneezing, lack of coordination and diarrhea.
Tips for preventing HPAI infection in birds includes bringing pet birds indoors or ensuring areas where backyard birds are kept are fully enclosed and away from wild birds and their droppings, washing or sanitizing your hands before and after handling birds and when moving birds between coops, keeping feed, water, equipment and other supplies secure/out of reach of wild birds or rodents, preventing visitors from contacting your flock and avoiding visits to places where other birds are kept. Immediately report any suspected infections to your veterinarian or state animal health official.
HPAI signs to watch out for in cats and dogs include fever, lethargy, low appetite, reddened or inflamed eyes, discharge from the eyes and nose, difficulty breathing, and neurologic signs, like tremors, seizures, incoordination or blindness.
Tips for preventing HPAI infection in dogs and cats are the same as for many other infectious diseases including keeping cats indoors, thoroughly washing your hands after handling your cat and after any encounters with poultry, livestock or wild birds and other animals, keeping pets that do go outdoors away from wild birds, poultry and cattle and their environments, preventing pets from eating dead birds or other animals, refraining from feeding cats any dairy products or colostrum that have not first been pasteurized or thoroughly cooked to kill the virus and avoiding feeding pets raw meat or poultry. Immediately contact your veterinarian if you notice any of these signs.
If you or someone around you has had direct contact with infected or potentially infected animals, including sick animals that might have eaten bird flu-infected birds, monitor symptoms for fever (although not always present) or feeling feverish/chills, tiredness, cough, sore throat, difficulty breathing/shortness of breath, conjunctivitis (eye tearing, redness, irritation or discharge from eye), headaches, runny or stuffy nose, muscle or body aches, diarrhea, vomiting and stomach pain.
Tips to protect yourself and others include washing your hands before and after handling animals, removing waste, feathers, and dirt first, using hand sanitizer if soap and water aren’t available, avoiding eating, drinking or touching your face while with animals, not letting kids kiss birds and washing their hands if they touch them, cleaning bird feeders, coops and pens wearing disposable gloves, using separate shoes/boots just for the coop or barn, not consuming raw milk or raw milk products and getting a regular flu shot.
The CDC states that “as a general precaution, people should avoid direct contact with wild birds and observe wild birds only from a distance, whenever possible. People should also avoid contact between their pets (e.g., pet birds, dogs and cats) with wild birds. Don’t touch sick or dead birds, their feces or litter, or any surface or water source (e.g., ponds, waterers, buckets, pans, troughs) that might be contaminated with their saliva, feces or any other bodily fluids without wearing personal protective equipment.”
Those encountering other sick or dead wild birds can report them to the Pennsylvania Game Commission by calling 1-833-PGC-WILD (1-833-742-9453), by emailing pgc-wildlifehealth@pa.gov or by using the online Wildlife Health Survey tool.
Any sick or dead domestic birds should be reported to Pennsylvania Department of Agriculture at 717-772-2852. If you have had contact with sick or dead birds and are not feeling well, contact your primary care physician or the Pennsylvania Department of Health at 877-724-3258
