5 Facts About the Bird Flu

Recent outbreaks of avian influenza in poultry and dairy cows have drawn attention to the disease commonly known as bird flu. Bird flu typically spreads among wild birds and other animals like dairy cows and domestic poultry, but this year, more than two dozen people across the United States have been infected.

Recently, the Centers for Disease Control and Prevention (CDC) confirmed 11 human cases in California and one in Missouri. The person in Missouri was the first to be diagnosed with the bird flu without having had known exposure to sick animals. But cases in humans remain rare — the people in California, Colorado, Texas, and Michigan who contracted the virus this year were all U.S. farm workers who were in close contact with infected animals, says the CDC.

“While the public health risk remains low at this time, the CDC is following the situation very closely,” says Dr. Magdalena Sobieszczyk, chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center. The CDC is utilizing its flu surveillance system to track cases in humans and are working with states across the U.S. to help monitor people most at risk at this time, such as those who have been exposed to infected birds, or other animals, or environments with animals infected with the bird flu.

Health Matters spoke with Dr. Sobieszczyk on what to know about the bird flu, such as the strains that are infecting humans, signs and symptoms, and whether it is safe to consume commercial milk.

There are many types of bird flu, but the most common are H5N1 and H7N9 bird flu viruses, which are found in wild birds. People become infected with the bird flu from close or prolonged unprotected contact with infected birds or animals. So far, the virus has not spread from human-to-human. The person who was infected in Missouri had no immediate exposure to animals, but is recovered now and there was no ongoing transmission among close contacts, according to the CDC.

Mild symptoms include:

• Eye redness consistent with what we call conjunctivitis
• Fever
• Cough
• Sore throat
• Muscle aches
• Fatigue

In more severe cases, the bird flu can cause respiratory infection, such as bronchitis, pneumonia, and respiratory failure, where the lungs get so inflamed that it is impossible for them to process oxygen. People may experience the same range of symptoms in traditional influenza A and influenza B, which is why we encourage people to get the flu vaccine to help prevent serious complications. Preventing seasonal influenza, especially in people who are exposed to the bird flu like farm workers, may reduce the risk of new strains of influenza emerging.

In April this year, concerns about bird flu in milk surged after strains were detected in samples of unpasteurized milk. But because the milk in grocery stores go through a pasteurization process, the FDA said it is safe to consume.

The pasteurization process, which has been around for 100 years, removes harmful bacteria and viruses by heating milk to a specific temperature for a set period of time to make milk safer, according to the FDA. Even if virus is detected in raw milk, pasteurization is generally expected to eliminate pathogens to a level that does not pose a risk to consumer health. Recently, the FDA and U.S. Department of Agriculture announced results of a study – published in the Journal of Food Protection in August 2024 – which further confirmed the effectiveness of the pasteurization process at removing the H5N1 virus in milk and other dairy products.

If you feel sick, speak with your doctor, and get tested. Chances are it could be other respiratory viruses like the regular flu, COVID-19, or RSV. Testing would be with a swab to look for viral particles that are present in the nasal secretions. Flu medication (antivirals) can treat bird flu in people and treatment works best when started as soon as possible after symptoms begin.

There is work and research being done to develop an mRNA vaccine that could be used for the bird flu. There is a vaccine for influenza A and B — the viruses most commonly found in humans — but it is not protective against the H5N1 bird flu. We still do not have all the data yet on exactly how this bird flu differs genetically from human influenza A and B.

While getting a seasonal flu vaccine will not protect against the H5N1 bird flu, we still recommend getting the shots. They protect us against the circulating forms of the regular virus. And flu vaccines are updated every year so that if there are new strains circulating, it will be incorporated into future vaccines. Although it is a rare and theoretical risk, it can also reduce the risk of getting sick with seasonal flu and the H5N1 bird flu simultaneously. Recently, the CDC announced that it would invest $10 million into buying and promoting seasonal flu shots and will work with state and local officials to get livestock workers vaccinated this fall.

Other protective measures include choosing pasteurized milk and making sure poultry is properly handled and cooked. If you are a farm worker, wear personal protective equipment (PPE) when in contact with dairy cows and other animals, and raw milk. Always wash your hands with soap. If you have symptoms, get tested and start treatment after talking to a clinician.

Magdalena Sobieszczyk, M.D., M.P.H., is the chief of the Division of Infectious Diseases at NewYork-Presbyterian/Columbia University Irving Medical Center and is the Harold Neu professor of infectious diseases in medicine at Columbia University Vagelos College of Physicians and Surgeons. Dr. Sobieszczyk is also a clinical virologist and the principal investigator of the Columbia Collaborative Clinical Trials Unit, funded by the National Institutes of Health, which has been advancing the science of infections like SARS-CoV-2 and HIV.