Since a rare fatal case of bird flu was reported in the United States in early 2025, there has been increased public concern about the disease. News sources indicate that the patient had underlying health conditions and possible exposure to infected wild birds, underscoring the potential human health risks associated with avian influenza.
This article reviews the H5N1 strain, commonly known as bird flu, focusing on how it may affect humans, including typical symptoms, modes of transmission, rarity of human cases, and preventive measures individuals and communities can consider.
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What is Bird Flu?
Bird flu, also known as avian influenza, is an influenza virus that primarily infects birds. Certain strains, such as H5N1, have the capacity to spread to other animals (including mammals) and, in rare cases, to humans. The H5N1 strain has been studied since it was first identified in 1997.
While bird flu overwhelmingly affects birds, human infections are uncommon but can be severe when they occur.
Previous notable outbreaks include H7N9 in 2013 and H5N6 in 2014. These designations (H and N) refer to two surface proteins of the virus—Hemagglutinin (H) and Neuraminidase (N)—which help scientists categorize the virus.
In birds, typical signs of avian influenza include watery or swollen eyes, lethargy, loss of appetite, fever, and respiratory distress. Severe cases may present with swelling of the comb and wattles (red fleshy areas on top of the head or under the neck of certain birds), discoloration of droppings, tremors, a swollen head, and even bleeding from the legs or neck.
How Does Bird Flu Spread?
Although most strains of bird flu remain limited to birds, some variants can spread to mammals, such as cats, and in rare instances to humans. Direct transmission from birds to humans is uncommon but may occur when people or other animals:
- Come into contact with infected birds’ feces or secretions.
- Inhale dust or aerosolized particles in environments where infected birds live.
- Share food or water sources with infected birds.
- Consume undercooked meat from infected animals.
Crowded conditions in poultry farms can facilitate the transmission and mutation of avian influenza strains. Domesticated cats and dogs sometimes become infected if they hunt or scavenge infected birds, potentially posing a secondary risk to humans who handle or care for these pets.
Animal to Human Transmission
Transmission of bird flu to humans is rare but can occur. Public health records over recent years show only a few confirmed cases in the United States, emphasizing how uncommon such infections are.
Still, it is important to remain vigilant and adopt practical measures to reduce potential risk. Bird flu can spread to humans when individuals:
- Touch infected animals (or their droppings) and then touch their mouth, nose, or eyes.
- Breathe in droplets or dust particles containing the virus, for example, when an infected bird flaps its wings.
- Handle sick or dead birds without appropriate protective equipment.
In the event of human infection, initial symptoms of bird flu often mirror those of seasonal influenza: fever, cough, sore throat, and muscle aches.
Additional, less common symptoms can include:
- Diarrhea
- Vomiting
- Conjunctivitis (pink eye)
- Chest pain
- Bleeding gums or nosebleeds
If untreated, these symptoms can progress to severe complications, such as pneumonia, encephalitis (brain inflammation), organ failure, and, in rare cases, seizures or loss of consciousness.
Individuals at higher risk of infection include:
- Farm workers
- Poultry farmers or hunters
- Home poultry keepers
- Petting zoo workers
- People with compromised immune systems
Diagnosis and Treatment
Individuals who suspect they may have contracted bird flu should consult a healthcare professional promptly. Delayed treatment can increase the risk of severe illness or complications.
Diagnosis often involves laboratory tests such as:
- Throat or nasal swabs
- Conjunctival swabs (if conjunctivitis is present)
- Sputum samples (if coughing up phlegm)
In addition to these tests, researchers are exploring the use of newer diagnostic tools to identify early signs of avian influenza. Preliminary studies suggest this approach may help detect outbreaks before they spread widely.
Treatment typically involves antiviral medications like oseltamivir (Tamiflu) or zanamivir (Relenza). Many patients experience symptom improvement with antivirals and supportive care, but outcomes vary. Anyone with persistent or worsening symptoms should seek further medical evaluation, which may include isolation or hospitalization if necessary.
Preventing Bird Flu
Preventing bird flu involves several straightforward measures. One of the most effective is thorough hand hygiene:
- Use warm water and ample soap.
- Lather and scrub the palms, backs of the hands, wrists, nails, and between fingers for at least 20 seconds.
- Rinse and dry thoroughly.
Additional precautions include:
- Avoiding unnecessary contact with birds, especially wild or visibly sick birds.
- Wearing gloves and other personal protective equipment (PPE) when handling birds or raw poultry.
- Thoroughly cleaning and disinfecting cooking surfaces and utensils.
- Avoiding the consumption of unpasteurized (“raw”) milk and undercooked poultry products.
Individuals at higher risk should strongly consider using PPE in certain work settings and staying current with seasonal influenza vaccines, which can reduce confusion between seasonal flu and potential avian flu infections.
Why Are Eggs So Expensive?
One indirect impact of avian influenza is its effect on food prices, particularly eggs. Since 2022, widespread outbreaks have required the culling of millions of commercial chickens, reducing egg supply.
Several news outlets have linked these outbreaks to higher egg prices, with some estimates placing the increase at over 70% in certain regions.
Although confirmed bird flu infections in cattle are extremely rare, disruptions in the broader agricultural sector—especially if there is a perceived risk to livestock—can influence the cost of other products, such as beef and milk.
In response to these challenges, the U.S. Department of Agriculture has allocated significant funding to prevent avian influenza’s spread, demonstrating the economic impact that even a relatively rare zoonotic threat can have on the food supply chain.
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Key Takeaways
- Bird flu (avian influenza) primarily affects birds, but in rare instances, it can infect humans and cause serious illness.
- Transmission to humans can occur through direct contact with infected birds’ feces or secretions, inhalation of contaminated dust, or handling/consuming infected animals without proper precautions.
- Diagnosis in humans is relatively straightforward with swabs (nasal, throat, or sputum), but early intervention is crucial for better outcomes.
- Prevention relies on thorough handwashing, using personal protective equipment when handling birds or poultry, and avoiding unpasteurized products.
- Bird flu outbreaks can significantly impact the economy by reducing poultry supply and raising food prices.
- Staying informed and sharing accurate information helps communities practice safer handling of animals and reduce transmission risks.
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