Summary about Disease
Extrinsic Allergic Alveolitis (EAA), also known as hypersensitivity pneumonitis, is an inflammatory lung disease caused by the inhalation of organic dusts or other allergens. This triggers an immune response in the small air sacs (alveoli) of the lungs, leading to inflammation and potentially lung damage with repeated exposure.
Symptoms
Symptoms can vary depending on the form of EAA (acute, subacute, or chronic). Common symptoms include:
Cough (dry or productive)
Shortness of breath
Fever
Chills
Muscle aches (myalgias)
Fatigue
Chest tightness
Weight loss (in chronic cases)
Causes
EAA is caused by inhaling various organic dusts or allergens. Common causes include:
Mold spores (from moldy hay, compost, or indoor environments)
Bird proteins (from bird droppings or feathers)
Bacteria (thermophilic actinomycetes in hot tubs or humidifiers)
Fungi (in mushroom farming)
Chemicals (isocyanates in paints and plastics) Specific examples include:
Farmer's Lung (moldy hay)
Bird Fancier's Lung (bird droppings/feathers)
Hot Tub Lung (bacteria in hot tubs)
Medicine Used
The primary treatment involves avoiding the offending antigen. Medications used to manage symptoms and inflammation include:
Corticosteroids: Prednisone is commonly used to reduce inflammation.
Immunosuppressants: In severe or chronic cases, medications like azathioprine or mycophenolate mofetil may be used to suppress the immune system.
Oxygen Therapy: Supplemental oxygen may be needed if blood oxygen levels are low.
Bronchodilators: These medications may help open the airways and ease breathing.
Is Communicable
No, extrinsic allergic alveolitis is not communicable. It is not an infectious disease and cannot be spread from person to person.
Precautions
The most important precaution is to avoid exposure to the causative antigen. Specific precautions depend on the source of the allergen:
Mold: Improve ventilation, remove sources of mold, use air purifiers.
Birds: Avoid contact with birds or bird droppings, use protective masks when cleaning bird cages.
Hot tubs: Maintain proper disinfection and pH levels in hot tubs.
Occupational exposures: Use appropriate respiratory protection (masks, respirators) in workplaces with potential exposures.
How long does an outbreak last?
The duration of an outbreak depends on the type of exposure (acute, subacute, or chronic) and the individual's response.
Acute: Symptoms may appear within hours of exposure and resolve within days to weeks after removing the antigen.
Subacute: Symptoms develop over weeks to months and may take several months to resolve after antigen removal.
Chronic: Symptoms persist for months to years, even after antigen removal, and may lead to irreversible lung damage.
How is it diagnosed?
Diagnosis typically involves:
Medical history and physical exam: Assessing symptoms and potential exposures.
Pulmonary function tests (PFTs): Evaluating lung capacity and airflow.
Chest X-ray or CT scan: Imaging the lungs to look for inflammation or fibrosis.
Bronchoalveolar lavage (BAL): Sampling cells from the lungs to identify inflammation.
Blood tests: Looking for antibodies specific to the suspected antigen.
Lung biopsy: In some cases, a small tissue sample may be needed to confirm the diagnosis.
Exposure history: Detailed information about the patient's environmental exposures.
Timeline of Symptoms
The timeline of symptoms varies depending on the form of EAA:
Acute EAA:
4-8 hours after exposure: Flu-like symptoms (fever, chills, muscle aches), cough, shortness of breath.
12-24 hours: Symptoms peak.
Days to weeks: Symptoms resolve with antigen avoidance.
Subacute EAA:
Weeks to months: Gradual onset of cough, shortness of breath, fatigue.
Months: Symptoms persist and may worsen if exposure continues.
Chronic EAA:
Months to years: Progressive shortness of breath, cough, fatigue, weight loss.
Irreversible lung damage may occur over time.
Important Considerations
Early diagnosis and antigen avoidance are crucial to prevent long-term lung damage.
Chronic EAA can lead to pulmonary fibrosis (scarring of the lungs), which is irreversible.
Accurate identification of the causative agent is essential for effective management.
Long-term follow-up with a pulmonologist is recommended to monitor lung function and manage symptoms.
Patient education on antigen avoidance and proper medication use is vital for successful treatment.