H5N1 (Avian Bird Flu) on Cape Cod

Bird Flu is a disease caused by certain Type A flu viruses that usually spreads between birds, NOT people. Some of these viruses can cause serious illness and death in domestic poultry including chicken, ducks, and turkeys. Avian influenza A viruses have been isolated from more than 100 different species of wild birds around the world. These viruses occur naturally among wild aquatic birds and shorebirds (ducks, geese, swans, gulls, terns, storks, plovers, and sandpipers) worldwide and can infect domestic poultry and other bird and animal species.

Wild birds can be infected with avian flu viruses without getting sick. However, they can shed avian influenza viruses in their saliva, nasal secretions, and feces. Susceptible domesticated birds become infected when they have contact with the virus as it is shed by infected birds.

Although highly pathogenic H5N1 avian influenza (commonly known as the bird flu), has been a public health concern for years, recent developments have heightened media attention and public awareness. Since March 2024, 67 people in the United States were diagnosed with H5N1 bird flu resulting from animal to human exposures (there have been no cases of human-to-human exposure). In 3 additional cases, an exposure source could not be identified. In most cases, symptoms were mild. On January 6, 2025, however, a Louisiana resident died from their infection marking the first H5N1 bird flu death of the current outbreak in the United States.

The wild bird H5N1 genotype was found in both the Louisiana patient who died after exposure to a sick backyard poultry flock, and a Canadian teen who was hospitalized in November. It appears that this genotype could be more hazardous to humans and is also dangerous to other animals. California has reported a few house cat deaths in animals exposed to raw pet food and raw milk.

To date, there have been no known human cases of H5N1 in Massachusetts. That said, the disease is widespread amongst bird populations nation-wide, making it essential that safety measures are taken to prevent spread of this potentially deadly disease.

Highly Pathogenic Avian Influenza (HPAI) or H5N1, commonly known as ‘bird flu’ was first found in wild birds on Cape Cod in the beginning of February 2022. Transmission in wild birds has increased in winter months, when waterfowl congregate together in search of unfrozen pond water and food. The disease does NOT pose an immediate health threat to people unless they have close, prolonged contact with infected animals. However, it does spread easily among wild and domestic birds, including poultry.

There have been numerous detections of H5N1 in wild birds in Barnstable County, Dukes County, Nantucket County, and Plymouth County in 2025. The natural reservoir for H5N1 is wild waterfowl (geese, ducks, swans, gulls, and shorebirds). H5N1 is considered widespread in Massachusetts waterfowl and has infected scavengers like raptors and mammals.

USDA has reported several instances of avian influenza (H5N1) in Massachusetts in domestic poultry. There have been no detections in commercial poultry farms in Massachusetts to-date. Detections have only been found in backyard (personal) flocks. The list below sorts detections starting with the most recent:

• • Dukes County: In February 2025, USDA confirmed Highly Pathogenic Avian Influenza (HPAI) in a 50-bird non-commercial backyard flock. The Massachusetts Department of Agricultural Resources (MDAR) took measures to depopulate and dispose of the flock to prevent further spread.
  • Plymouth County: In January 2025, a 30-bird backyard poultry flock tested positive. MDAR depopulated and disposed of the flock to prevent further spread.

• • Essex County: In March 2024, a 70-bird flock tested positive for HPAI. MDAR depopulated and disposed of the flock to prevent further spread.
  • Essex County: In February 2024, a 20-bird flock tested positive for HPAI. MDAR depopulated and disposed of the flock to prevent further spread.

• • Barnstable County: In January 2024, a 150-bird non-commercial backyard flock tested positive for HPAI. MDAR depopulated and disposed of the flock to prevent further spread.
  • Middlesex County: In November 2022, a 20-bird backyard flock tested positive. MDAR depopulated and disposed of the flock to prevent further spread.
  • Bristol County: In September 2022, a 50-bird backyard flock tested positive. MDAR depopulated and disposed of the flock to prevent further spread.
  • Berkshire County: In March 2022, a 260-bird backyard flock tested positive. MDAR depopulated and disposed of the flock to prevent further spread.

People rarely get bird flu, but when they do, it’s most often through prolonged unprotected contact (failure to use gloves, eye protection, or a facemask/respirator) with infected birds. People can become infected by breathing the virus in droplets in the air or possibly dust, or by touching surfaces contaminated with infected bird mucous, saliva, or feces and then touching their eyes, nose, or mouth. Most bird flu infections in people have happened after close, prolonged, unprotected contact with infected birds or contaminated surfaces. No human bird flu infections have been reported from proper handling of poultry meat or from eating properly cooked poultry or poultry products.

Overall, the risk to the public from bird flu outbreaks is low; however, because bird flu viruses have been known to infect people sporadically (again, people who were known to have prologued, unprotected exposure to infected birds), it is possible that human infections with these viruses could occur. It is important to note there has been no known human-to-human spread of bird flu.

CDC Infographic: How Infected Backyard Poultry Could Spread Bird Flu to People

H5N1 Bird Flu: Current Situation | Bird Flu | CDC

You should be vigilant about protecting your flock, and/or any domestic avian pets, from bird flu. Highly Pathogenic Avian Influenza is named that way due to its deadly effect on poultry. Prevent exposures to your flock by following MDAR guidance including:

• Do not allow poultry to free range. This increases the risk of contact with wild waterfowl or their droppings.
• Eliminate standing water and prevent domestic birds from having access to ponds, streams, and wetland areas that attract wild waterfowl.
• Keep your birds inside a building. If the birds use an outside enclosure, be sure that it is covered with netting to prevent wild birds from flying into it.
• Keep a dedicated pair of footwear that is only worn when caring for your flock OR use a bucket and brush with disinfectant to scrub the soles of your footwear prior to entering the poultry house.

Learn more about biosecurity to protect your poultry at USDA Defend the Flock.

Infected poultry, and possibly pet birds, may show one or more of the following signs of HPAI H5N1:

• • 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

• • Diarrhea

If you notice symptoms in your poultry flock, report it immediately to your local health department AND Massachusetts Department of Agricultural Resources at www.mass.gov/reportpoultry or by calling (617) 626-1795.

Immediately call your local health department AND report to the Massachusetts Department of Agricultural Resources, Animal Health Division:

• Call (617) 626-1795.
• Submitting online at www.mass.gov/reportpoultry

For the first time in 2024, the H5N1 virus was found to have mutated to infect and transmit between dairy cows. No infected cows have been identified in Massachusetts or New England, however, 16 states have reported infected cows. Genetic analysis suggests that after a cow was infected by wild birds (likely through water or feed contaminated with bird feces), the virus then mutated to be able to spread within herds. There is currently no evidence that wild birds are continuing to infect dairy cattle, however, the risk cannot be ruled out (1).

Concerningly, H5N1 virus has been found in the milk of infected cows, posing a risk to dairy ranchers. Workers should be especially vigilant for signs of illness in their animals and wear protective gear if animals are sick. As of this article’s publication, 40 people in the U.S. have been infected from dairy cows. Nearly all of these infections have been mild, with symptoms like conjunctivitis (pink eye). Fortunately, pasteurization has proven to effectively kill H5N1 virus, thereby eliminating risk to the pasteurized milk supply or consumers. Even before H5N1 public health has strongly discouraged drinking raw milk due to its risk for transmitting infectious diseases. The recommendation NOT to drink raw milk is even stronger now.

Although bird flu viruses mainly infect and spread among wild migratory water birds and domestic poultry, some bird flu viruses can infect and spread to other animals as well. Bird flu viruses have in the past been known to sometimes infect mammals that eat (presumably infected) birds or poultry, including but not limited to wild animals, such as seals, bears, foxes, skunks; farmed mink; stray or domestic animals, such as cats and dogs; and zoo animals, such as tigers and leopards.

If your domestic animals (e.g., cats or dogs) go outside and could potentially eat or be exposed to sick or dead birds infected with bird flu viruses, or an environment contaminated with bird flu virus, they could become infected with bird flu. While it’s unlikely that you would get sick with bird flu through direct contact with your infected pet, it is possible.

For more information visit: Bird Flu in Pets and Other Animals | Avian Influenza (Flu) (cdc.gov)

People who have had direct contact with infected or potentially infected animals, including sick animals that might have eaten bird flu-infected birds, should monitor their health for fever and symptoms of infection.

Signs and Symptoms may include:

• • Fever (Temperature of 100°F [37.8°C] or greater) or feeling feverish/chills*

• • 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

*Fever may not always be present.

If you develop any of these signs or symptoms during the 10-days after your exposure to an infected or potentially infected animal, call the Bureau of Infectious Disease and Laboratory Sciences Division of Epidemiology at (617) 983-6800. The on-call epidemiologist is available during normal business hours for emergencies and to answer questions regarding case investigation and implementation of control measures. Discuss your potential exposure and ask about testing. If testing is recommended, isolate as much as possible until test results come back and/or you have recovered from your illness.

Cape Wildlife Center is a veterinary hospital in Barnstable that provides rehabilitative care to sick, injured, and orphaned wild animals. Call for immediate assistance and wildlife emergencies: (508) 362-0111. Admissions hours are between 10:00 AM and 3:00 PM daily. Afterhours emergency line: (617) 835-6845.

Wild Care, Inc. is a wildlife rehabilitation center in Eastham that treats injured, ill, and orphaned wildlife for release: If you find an animal in distress, call: (508) 240-2255. Wild Care, Inc. is open daily from 9:00 AM to 5:00 PM.

MassWildlife is collecting information on wild birds to monitor possible outbreaks of Avian Influenza. They are particularly interested in sick/dead seabirds washing up along coastal areas. Please click the following link to complete an online form and include a photo if possible: Report observations of dead wild birds | Mass.gov.

PLEASE NOTE: An individual dead wild bird does not generally require testing or removal. However, removal/disposal of dead birds from the environment is a good practice to help reduce environmental contamination and potential exposure to other birds and mammals. No single entity is responsible for the removal/disposal of dead birds; it is dependent on the municipality and the landowner.

For information about how to safely dispose of a dead bird or animal, please visit: Found a Dead Wild Bird? Here’s What To Do Next (usda.gov).