Chickens can carry several diseases that spread to humans, ranging from common bacterial infections like Salmonella and Campylobacter to respiratory illnesses like bird flu and psittacosis. Most transmission happens through direct contact with birds or their droppings, handling contaminated eggs, or breathing in dust from coops and litter. The risk is highest for backyard flock owners, but some of these pathogens also reach people through undercooked poultry and eggs bought at the store.
Salmonella: The Most Common Risk
Salmonella is the single biggest disease risk associated with chickens. The CDC estimates it causes 1.35 million infections, 26,500 hospitalizations, and 420 deaths in the United States every year. Over 23% of foodborne Salmonella cases come from eating chicken or turkey, and the bacteria also spread through direct contact with live birds.
Backyard flocks are a consistent source of outbreaks. The CDC regularly tracks Salmonella clusters tied to people handling their own chickens, collecting eggs, or cleaning coops. Chickens can carry Salmonella in their intestines and shed it in droppings without ever looking sick, which means a healthy-looking bird can still be infectious.
One particularly concerning strain, Salmonella Enteritidis, can contaminate eggs before the shell even forms. The bacteria travel from a hen’s intestines into her bloodstream, eventually colonizing her reproductive organs. From there, Salmonella gets incorporated into the egg white, the shell membranes, or the shell itself while the egg is still developing inside the bird. This means even eggs with intact, clean shells can harbor bacteria internally. Making matters worse, contaminated eggs look, smell, and feel completely normal, and the bacteria multiply rapidly at room temperature.
Campylobacter and Foodborne Illness
Campylobacter is another bacterial infection closely tied to poultry. It’s actually the leading cause of bacterial diarrhea in the United States, and chicken is its primary vehicle. The bacteria live in the intestines of healthy chickens and contaminate meat during processing. In humans, infection causes diarrhea (often bloody), stomach cramps, nausea, and fever, typically starting two to five days after exposure and lasting about a week.
Unlike Salmonella, Campylobacter rarely makes headlines because outbreaks tend to be smaller and more scattered. But the sheer number of individual cases makes it a major public health concern. Handling raw chicken and then touching your mouth, or eating undercooked poultry, are the most common ways people get infected.
Bird Flu (Avian Influenza)
Bird flu, caused by avian influenza A viruses like H5N1, is rarer than bacterial infections but carries more serious potential consequences. Most human cases in the United States have been mild so far, and nearly all have occurred in people with direct exposure to sick or infected birds.
The most common symptom in recent U.S. cases has been eye redness, or conjunctivitis. Other mild symptoms include low-grade fever, cough, sore throat, runny nose, muscle aches, headache, and fatigue. Fever isn’t always present. In more severe cases, bird flu can cause high fever, shortness of breath, altered consciousness, and seizures, though these outcomes have been uncommon domestically.
The virus spreads when people inhale contaminated dust or droplets, or touch infected birds and then touch their eyes, nose, or mouth. Backyard flock owners face the highest risk, especially when cleaning coops, handling sick birds, or dealing with birds that have died unexpectedly.
Psittacosis
Psittacosis is a bacterial lung infection caused by Chlamydia psittaci, an organism that chickens, turkeys, parrots, and pigeons can all carry. People catch it by breathing in dried particles from bird droppings, feather dust, or respiratory secretions. Symptoms resemble pneumonia: fever, chills, headache, dry cough, and muscle aches.
The infection is tricky because it mimics many other respiratory illnesses, and doctors don’t always think to ask about bird exposure. If you keep chickens and develop a persistent cough with fever, mentioning your flock to your healthcare provider can help point them toward the right diagnosis and testing.
Histoplasmosis From Coop Environments
Histoplasmosis isn’t carried by chickens directly. It’s caused by a fungus that thrives in damp soil enriched by bird and bat droppings. Chicken coops, old barns, and pigeon roosts are prime environments. When you disturb contaminated soil or dried droppings, fungal spores become airborne and can be inhaled.
Symptoms typically appear 3 to 17 days after breathing in the spores and include fever, chills, headache, muscle aches, dry cough, chest pain, and fatigue. Most people recover without treatment, but a chronic form can develop in the lungs, causing weight loss, bloody cough, and breathing difficulties. Wetting down surfaces in coops and barns before cleaning helps keep spores from becoming airborne.
Newcastle Disease
Newcastle disease is a serious viral illness in poultry that occasionally crosses over to humans in very limited ways. Human infections are rare and almost exclusively occur in people working directly with sick birds or administering vaccines to flocks. When it does affect people, the typical symptom is conjunctivitis. It does not cause the severe respiratory or neurological disease in humans that it causes in birds.
Antibiotic-Resistant Bacteria
Beyond specific named diseases, chickens can harbor bacteria that have developed resistance to multiple antibiotics. A 2020 study of retail chicken carcasses found that 63.4% of E. coli samples isolated from the meat were multidrug-resistant. While E. coli from chicken doesn’t always cause illness on its own, resistant bacteria can transfer their resistance genes to other bacteria, making future infections in humans harder to treat. This is one reason thorough cooking and careful handling of raw poultry matter so much.
Who Faces the Highest Risk
Young children are especially vulnerable. They’re more likely to touch birds and then put their hands in their mouths, and their immune systems are less equipped to fight off infections like Salmonella. The CDC recommends that adults supervise handwashing for young children after any contact with poultry. People with weakened immune systems, older adults, and pregnant women also face elevated risks from most of these infections.
Backyard flock owners generally face more disease exposure than people who only encounter chicken as food. Cleaning coops, collecting eggs, and handling birds create repeated opportunities for contact with droppings, feather dust, and contaminated surfaces.
Reducing Your Risk
Wash your hands with soap and running water every time you touch your birds, collect eggs, or handle feeders, waterers, or coop equipment. Keep hand sanitizer near your coop for times when a sink isn’t convenient. Use a dedicated pair of shoes for poultry care and leave them outside your house.
Clean all coop equipment outdoors. Wear gloves when handling droppings or scrubbing enclosures. Remove visible debris with warm soapy water first, then apply a diluted bleach solution or commercial disinfectant to the cleaned surface. Most disinfectants only work on surfaces that have already been scrubbed clean, and they need to sit for the contact time listed on the label (usually 30 seconds to 10 minutes) before you rinse.
If you’re dealing with sick or dead birds, or if bird flu has been reported in your area, the CDC recommends wearing full protective equipment: safety goggles, disposable gloves, waterproof boots, a well-fitting mask or N95 respirator, disposable coveralls, and a head cover. Avoid stirring up dust and feathers, which can disperse viruses into the air. Remove protective gear in a clean area away from the coop, dispose of single-use items, and shower immediately afterward. Wash any clothing worn underneath in detergent and dry it on high heat before wearing it again.
For eggs, refrigerate them promptly and cook them until both yolk and white are firm. With raw chicken from any source, use separate cutting boards, wash surfaces that contacted raw meat, and cook to an internal temperature of 165°F.