Bird fancier’s lung is a type of hypersensitivity pneumonitis caused by exposure to avian proteins found in the dry dust of the droppings and feathers of a variety of birds. It is an uncommon but potentially serious lung disease that can develop over months or years in susceptible individuals who keep and work with birds as a hobby or occupation. The time it takes to develop bird fancier’s lung can vary substantially between individuals based on the type, frequency, and intensity of exposure to bird allergens.
What is Bird Fancier’s Lung?
Bird fancier’s lung, also known as bird breeder’s lung or pigeon breeder’s disease, is a type of extrinsic allergic alveolitis caused by an immune system response to repeated inhalation of avian proteins. When birds preen and ruffle their feathers, this releases fine dry dust containing proteins from their droppings, dander, and feathers into the air which can be easily inhaled. In some susceptible individuals, this triggers a hypersensitivity reaction in the lungs that causes inflammation and scarring of the alveoli and bronchiolar walls. This reduces the ability to oxygenate blood properly.
The most common birds implicated in bird fancier’s lung are pigeons, parakeets, cockatiels, budgerigars, and parrots. However, proteins from chickens, turkeys, ducks, geese, pheasant, and a variety of wild birds can also cause the disease. It is most frequently seen in pigeon breeders, but bird fanciers, veterinarians, pet shop workers, zookeepers, poultry farmers, and feather duvet makers may also be at risk.
Symptoms
The symptoms of bird fancier’s lung often come on gradually over weeks or months of continued exposure. They include:
– Shortness of breath, especially with exertion
– Wheezing or coughing, sometimes with phlegm production
– Tightness in the chest
– Fatigue
– Loss of appetite and weight loss in some cases
– Occasional fever and night sweats
As damage to the lungs worsens, symptoms may become persistent. Severe or untreated cases can lead to pulmonary fibrosis, permanent shortness of breath, respiratory failure, pulmonary hypertension, and even death.
Onset of Symptoms
It usually takes repeated or continuous exposures over an extended period to trigger the development of bird fancier’s lung. The time it takes depends on several factors:
– Type of birds kept – Some bird species like pigeons, budgies, and cockatiels produce proteins that are more allergenic and likely to trigger disease.
– Number of birds – The more birds one is exposed to, the higher the concentration of avian proteins and risk of sensitization.
– Amount of contact – Those who spend more time cleaning cages, handling birds, or in enclosed spaces with birds are more likely to inhale problematic amounts of allergens.
– Ventilation – Poor ventilation increases concentration of bird proteins in the air.
– Atopy – Individuals with a genetic predisposition for hypersensitivity reactions like asthma are at greater risk.
– Smoking – The lungs’ defenses are impaired, increasing susceptibility.
For most, symptoms start within 1 to 5 years of regular exposure, though it can happen sooner. On average, bird fancier’s lung develops within 3 years of substantial contact with birds. Some develop symptoms after 6 months while others take up to 15 years to manifest. The onset also tends to be shorter with intense or continuous exposure. Anyone with persistent respiratory symptoms who works with birds should be evaluated for bird fancier’s lung.
Diagnosis
Bird fancier’s lung is diagnosed with a combination of an exposure history, physical exam, imaging tests, and laboratory tests. These include:
– Detailed history of bird exposures at home and work.
– High resolution CT scan showing interstitial lung changes.
– Pulmonary function tests showing restrictive or obstructed ventilation.
– Bronchoscopy with biopsies showing chronic bronchiolitis.
– Blood tests confirming elevated IgA and IgG antibodies against avian proteins found in that individual’s birds.
– Inhalation challenge testing with avian antigens.
Making the diagnosis can be tricky as symptoms mimic many other respiratory diseases. Around 33% of people suspected to have bird fancier’s lung have an alternate final diagnosis upon further testing.
Treatment
The most effective treatment for bird fancier’s lung is identifying and completely avoiding the causative avian antigens. This means no longer keeping or working with birds in an enclosed space. In occupational cases, it requires changing jobs. Most people begin improving within several weeks to months after cessation of exposure and have resolution of symptoms over time.
Medications such as corticosteroids and immunosuppressants may be used to reduce inflammation in the short term. Oxygen therapy can help those with severe respiratory impairment. Lung transplantation is a last resort treatment for end-stage disease. Even after diagnosis, continued exposure can lead to irreversible lung damage. Early identification and prompt avoidance of antigens is key to regaining lung health.
Prognosis
When caught early and exposure is stopped, the majority of patients with bird fancier’s lung recover with minimal lasting lung dysfunction. In one long term study, 68% had normal pulmonary function tests and 94% had only mild or moderate disease after 7.5 years. However, delayed diagnosis or ongoing antigen exposure increases the risk of permanent pulmonary fibrosis and gradual respiratory decline. About 29% develop progressive disease leading to respiratory failure or cor pulmonale. Overall, bird fancier’s lung has a 5% mortality rate when properly identified and managed.
Prevention
Preventing bird fancier’s lung centers on limiting exposure to bird proteins:
– Avoid keeping birds in the home, especially in bedrooms or poorly ventilated areas.
– Use HEPA filters, fans, and ventilation systems in areas where birds are housed.
– Clean cages, change litter, and handle birds in well-ventilated spaces, preferably outdoors.
– Wear an N95 mask when cleaning cages or working in enclosed spaces with birds.
– Shower and change clothes after working with birds to avoid carrying allergens elsewhere.
– Have birds examined by a vet for illness, which increases allergen production.
– Avoid smoking and other lung irritants.
– Consider allergy testing if working with birds for a living. Stop immediately if sensitization detected.
While bird fancier’s lung cannot always be prevented in those working closely with birds, these measures help reduce risk and allow early diagnosis and intervention if symptoms do develop.
Conclusion
Bird fancier’s lung is an occupational and hobby-related lung disease caused by allergic reaction to avian proteins from birds like pigeons, parrots, and chickens. On average, it takes about 3 years of substantial exposure for symptoms like cough, wheeze, and shortness of breath to develop, but the onset period is highly variable between individuals and dependent on the frequency and intensity of contact. Preventive strategies like ventilation, masks, and allergy testing help reduce risk in those who keep or work with birds. Bird fancier’s lung can lead to irreversible lung damage but has a relatively good prognosis when properly diagnosed early and further exposure is halted. The key is recognizing the symptoms are due to an allergic reaction and completely removing the triggers to preserve lung function.
