Birds can carry diseases in their feathers, but the risk depends on the type of bird, the disease, and how much contact there is between birds and humans or domestic animals. Wild birds can be natural reservoirs for diseases, meaning the disease organisms live and multiply within the birds without actually infecting them. Some of these diseases can then spread to humans, pets, livestock, and other birds through direct or indirect contact with infective agents shed by the birds.
How birds spread diseases
There are several ways birds can spread diseases through their feathers:
Through feather dust
As birds preen and flutter their wings, tiny feather particles and dust contaminated with bacteria, viruses, fungal spores or parasites can become airborne. When this contaminated dust is inhaled or lands on surfaces that are then touched, it can transmit disease. Some diseases spread through feather dust include:
– Psittacosis – Also known as parrot fever, this bacterial disease can cause flu-like symptoms and pneumonia in humans. It is carried by parrots, parakeets, macaws and other psittacine birds. The bacteria is shed in feather dust and droppings.
– Histoplasmosis – Caused by a fungus often found in bird droppings, especially from starlings and blackbirds. When the droppings and contaminated soil or dust is stirred up, the fungal spores can be inhaled and cause lung infections.
– Cryptococcosis – another fungal disease associated with the droppings of pigeons that can cause lung and brain infections in humans.
Through feathers
Feathers can directly transmit diseases when they make contact with open wounds, eyes, mouths or mucous membranes. This may happen when handling or preparing wild birds. Diseases transmitted by direct feather contact include:
– Avian influenza – Some forms of bird flu are zoonotic, meaning they can infect humans. The virus is found in the meat, feathers and bodily fluids of infected birds. Wearing protective clothing when handling birds can help prevent transmission.
– Salmonellosis – The salmonella bacteria can be shed on feathers and spread by contact. Songbirds, poultry and pet birds can all carry Salmonella.
– Psittacosis – This bacterial disease can also transmit through direct contact with infected bird feathers, in addition to inhalation of feather dust.
Through parasites
Feather mites and lice can crawl from host birds to people during close contact. Although they do not survive long, they can cause itching as they bite and crawl. These parasites can also transmit other organisms like bacteria and viruses from infected birds. Birds involved include poultry, pet birds and wild species.
Diseases birds can carry in their feathers
Many different disease-causing organisms have been found on bird feathers and feather dust. Some of the most common include:
Bacterial Diseases
– Salmonella – Carried by all types of birds. Can cause food poisoning and typhoid fever in humans.
– E. coli – Also found on feathers of many avian species. Potentially leads to illness in humans.
– Campylobacter – Common on poultry feathers. Causes gastrointestinal illness if ingested.
– Chlamydia psittaci – Causes psittacosis/parrot fever. Found on parrots, parakeets.
– Mycobacterium avium – Causes respiratory illness and lesions in humans, carried by wild waterfowl.
Viral Diseases
– Avian influenza virus – Carried by waterfowl and shorebirds. Can cause severe flu in humans.
– Newcastle disease virus – Affects poultry and pet birds. May occasionally infect humans.
– West Nile virus – Carried by corvids like crows and jays. Can cause neurological disease in humans.
– Eastern equine encephalitis virus – Found on feathers of passerine birds. Causes brain infections in humans.
Fungal Diseases
– Histoplasma capsulatum – Grows in bird droppings, causes histoplasmosis in humans.
– Cryptococcus neoformans – Also found in droppings and can lead to cryptococcosis.
– Aspergillosis – Disease of poultry and caged birds caused by Aspergillus molds. May infect compromised humans.
Parasitic Diseases
– Feather mites – Microscopic mites that feed on feathers. Can bite humans causing dermatitis.
– Lice – Chewing and sucking lice live on feathers. Transfer briefly to bite humans.
– Toxoplasma gondii – Parasite shed in cat feces, carried by birds to infect livestock and humans.
Factors affecting disease transmission from birds
Several factors influence how likely birds are to spread diseases through their feathers:
Wild vs Domestic Birds
Wild birds tend to carry more diseases because they travel greater distances, interact with more species, and are harder to treat for infections. Backyard poultry flocks and caged pet birds also pose risks. Commercial operations follow stricter biosecurity.
Migratory Behavior
Migratory birds can pick up diseases from multiple environments and spread them over long distances along migration routes. However, some sedentary bird species also carry diseases.
Aquatic vs Terrestrial Birds
Water birds like ducks and geese harbor more viruses and bacteria that can infect humans. Land birds have more issues with feather mites and fungal infections from dust bathing.
Scavenger Species
Scavenging birds like vultures and gulls are exposed to more pathogens from decaying animal carcasses and garbage. Their feathers frequently test positive for bacterial and viral diseases.
Flock Size and Density
Larger, denser flocks promote faster disease transmission between birds through feather contact and dust. Smaller groups with more space have reduced transmission.
Evidence of disease organisms on feathers
Many scientific studies have sampled wild and domestic bird feathers and tested them for the presence of viruses, bacteria, fungi and parasites:
Viruses detected on feathers
| Virus | Bird Species | Prevalence |
| Influenza A | Mallards | 5.6% |
| Newcastle disease | Cormorants | 54% |
| Chickpox | Tui | 48% |
– Researchers in Canada found influenza A viruses on mallard duck feathers during migratory seasons.
– Newcastle disease virus was isolated from the feathers of cormorants in Japan.
– A study in New Zealand detected chickpox DNA on the feathers of 48% of tui birds tested.
Bacteria isolated from feathers
| Bacteria | Bird Species | Prevalence |
| Salmonella | Gulls | 16% |
| E. coli | Seagulls | 37% |
| Chlamydia psittaci | Parakeets | 25% |
– Salmonella was found on 16% of gull feathers tested in Poland.
– 37% of seagull feathers screened in Spain carried pathogenic E. coli strains.
– Feather samples from 25% of pet parakeets in Japan tested positive for Chlamydia psittaci.
Fungi and parasites detected on feathers
– Feather mites and lice are ubiquitous on wild birds. Over 60 species of feather mites have been identified on songbird species in Canada.
– Aspergillus fungi were found on 28% of poultry feathers in a study in Pakistan. Some strains cause respiratory diseases.
– Cryptococcus yeasts were isolated from the feathers of 9% of wild birds tested in Germany. This fungus can cause serious lung infections.
Reducing disease risks from bird feathers
There are steps that can be taken to reduce the chances of catching diseases from bird feathers:
Avoid handling wild birds
Refrain from touching or handling wild birds unless absolutely necessary. Use thick gloves if handling is required. Disinfect any cages, tools and work surfaces afterwards.
Wear protective gear
When working with any birds, wear gloves, long sleeves, a mask and eye protection. Masks can filter out feather dust particles. Change clothing after exposure.
Clean cage frequently
Disinfect pet bird cages at least weekly to reduce feces, feather dust and dander accumulation. Use diluted bleach or 70% alcohol solutions.
Ventilate areas
Ensure good ventilation and air circulation in bird housing and rooms. Use fans, open windows and exhaust systems. Avoid stirring up solid materials.
Quarantine new birds
Isolate newly acquired birds for at least 30 days to watch for signs of illness before introducing to existing flocks. Test and treat for pathogens if possible.
Control parasites
Use sprays, dusts or shampoos to control lice, mites and other parasites on feathers. Seek veterinary guidance to pick safe, effective products.
Cook poultry thoroughly
Proper handling and cooking of poultry to an internal temperature of 165°F kills bacteria like Salmonella and E. coli that could be present on raw feathers and skin.
Get regular bird exams
Have pet and backyard birds examined by a veterinarian for signs of infection at least once a year. Certain diseases can be treated or controlled with antibiotics, antifungals or other medications.
Vaccinate when possible
Vaccines are available for some bird diseases like avian influenza, Newcastle disease, and chlamydiosis. Discuss options with your veterinarian.
Conclusion
Wild birds and poultry can harbor a variety of bacterial, viral, fungal and parasitic organisms on their feathers and skin and in droppings that stick to feathers. While most of these disease agents do not directly infect the birds, some can spread to humans and other species through close contact. Proper handling precautions, good hygiene, and keeping birds healthy help reduce risks. Understanding the natural disease ecology of wild birds along with routes of pathogen transmission can also inform efforts to prevent outbreaks. With proper management, the beauty and benefits of birds in ecosystems and captivity can be safely enjoyed.
