1. Extrinsic allergic alveolitis (hypersensitivity pneumonitis, EAA)
Immunologically mediated inflammatory reaction in the alveoli and in the respiratory bronchioles
causes: organic dusts (<5µm) moulds foreign proteins some chemicals diisocyanates organic acid anhydrides
often heavy, repeated exposure, most often at the work place
hkes03

2. EAA
Pathology: Granulomatotic inflammation around the alveoli and the peripheral bronchioles. Exudate with plasma cells and lymphocytes. Macrophages, epitheloid cells and giant cells in the granulomas in the middle of the inflammation process.
After the exposure ceases the reaction disappeares in 3-4 months.
If the exposure continues, the exudation organises into fibrine and an irreversible pulmonary fibrosis follows.

3. Examples of EAA Etiology
Farmer's lung mouldy hay
Saw mill worker's lung mouldy wood dust
Bird fancier's lung proteins in bird droppings
Mushroom worker´s lung spores, moulds
Malt worker´s lung mouldy malt
Humidifier lung contaminated humidifier water
Cheese washer's lung Penicillium casei
Suberosis cork dust mould
Diisocyanate lung polyurethane hardeners
Hard metal worker's lung hard metal dust, cobalt

4. Allergic alveoltis in Finland 1981-2001 (Finnnish Register of Occupational Diseases)

5. SRR (standardized risk ratio) of EAA in some occupations
Occupation SRR n
farmers and cattle tenders 9.2 (8.4-10) 928
other printing workers (2.2-13) 5
bookbindery workers (1.7-5) 7
printers ( ) 10
wood workers ( ) 13
typesetters ( ) 10
Keskinen et al. Työperäiset hengtystieallergiat. Jauhoastmasta sementti-ihottumaan.Työterveyslaitos, Helsinki 1997

6. EAA, symptoms flu-like illness cough high fever, chills
dyspnea, chest tightness
malaise, myalgia 4-8 hours after exposure
chronic disease: dyspnea in strain, sputum production, fatigue, anorexia, weight loss

7. EAA, clinical findings
Status dyspnea, cyanosis, crepitant rales digital glubbing (chronic form)
Chest X-ray normal or small nodules/diffuse infiltrates/ ground glass appearance chronic form: pulmonary fibrosis HRCT normal or ground glass appearance centrilobular micronodules
lung function restriction, diffusing capacity decreases, hypoxemia, obstruction, hyperreactivity
lab. tests rise of sedimentation rate, leukocytosis, neutrophilia
BAL marked lymphocytosis, T helper / T supressor cells decreased

8. EAA: HRCT, acute disease

9. EAA: HRCT, chronic disease

10. Diagnostics of EAA
Main criteria 1. Exposure to arganic dust (history, spesific IgG antibodies, work place measurements). 2. Typical symptoms 3. Chest X-ray findings
Additional criteria 1. Decreased diffusion capacity 3. Hypoxia during rest or decreasing during excercise 4. Restriction in spirometric values 5. Lung biopsy with findings of allergic alveolitis 6. Provocation test (at work place) positive All main criteria and two of the additional ones are needed for diagnosis (Terho, Keuhkosairaudet, Duodecim 20

11. EAA, differential diagnostics
Organic Dust Toxic Syndrome (ODTS)
Sarcoidosis
Drug-induced pneumonitis
Viral and mycoplasma pneumonias
Tuberculosis
Allergic bronchopulmonary aspergillosis
Collagen-vascular diseases
Lymphangitis carcinomatosa
Pulmonary fibrosis (DIP)
Pneumoconioses

12. EAA, treatment Stopping of exposure Oral steroids
Farmer's lung: after recovery back to work excluding/minimizing the exposure
motorized respiratory ventilator, training!
after reorganization of the job description
follow-up

13. EAA, prognosis
Continuing exposure, relapsing disease leads to pulmonary fibrosis, permanent loss of pulmonary function and cor pulmonale.
When Finnish cases with farmer's lung were followed for 10 years, 23% had findings of pulmonary emphysema or pulmonary fibrosis.

14. EAA, prevention reduction of dust exposure work hygienic improvements
adequate respirators always during exposure - before any symptoms!
occupational health care
information
follow-up
finding symptomatic workers in time, to prevent permanent loss of pulmonary function

15. Organic Dust Toxic Syndrome (ODTS)
opening of silos pulmonary mycotoxicosis
exposure to grain grain fever
1986 diPico ODTS
Etiology: heavy exposure to biological organic dusts mycotoxins and endotoxins
No sensitization
No latency time
prevalence numbers farmers 14% mushroom cultivation 37%

16. ODTS Symptoms: Symptoms mild to severe, ceasing when no exposure
fever, main symptom
cough
irratative symptoms of mucous membranes
fatigue
myalgia
Symptoms mild to severe, ceasing when no exposure
Symptoms milder than in allergic alveolitis
No chronic form?

17. ODTS, diagnostics Criteria not yet clear
Investigated as allergic alveolitis
Exposure and timing of symptoms important, often a few hours after exposure.
No findings in chest X-ray
lung function: normal or as in EAA but mild
BAL: neutrophilia?
Work place provocation test following symptoms, temperature, diffusion capacity and FEV1/PEF

18. Differential Diagnostics: Extrinsic allergic alveolitis (EAA)/Asthma(OA)/ODTS
Feature EAA OA ODTS
Symptoms Cough, dyspnea Cough, dyspnea Flu-like symptoms fever fever
Onset after exposure Gradual after 4-8h Immediate or Gradual after 3-8h late
Physical findings Bibasil. crackles Expirat. wheezes None
Chest X-ray Infiltrates/norm. Normal Normal
Lung function Restrictive Obstructive Normal?
Peripheral eosinophilia No Yes? No

19. Conclusion
Farmer´s lung is the most usual extrinsic allergic alveolitis. Chronic form leads to severe disability.
Reduction of the exposure to biological dust by work hygienic improvements and using adequate respirators is important. The humidifiers and other sources of exposure should be cleaned.
Early recognition of the symptoms is essential.
ODTS is a milder syndrome, symptoms can be prevented using respirator when exposed.

20. Literature
Pickering CAC, Newman Taylor AJ. Extrinsic allergic bronchioloalveolitis (hypersensitivity pneumonia). In RW Parkes, Occupational Lung Disorders, Third edition1994, Butterworth Heineman Ltd, UK,
Terho EO. Orgaanisten pölyjen aihettamat keuhkokudoksen yliherkkyysreaktiot. Kirjassa Allergologia, toim. Haahtela T, Hannuksela M, Terho E.O. Kustannusosakeyhtiö Duodecim, 1999:
Terho EO. Allerginen alveoliitti ja sitä muistuttavat sairaudet. Kirjassa Keuhkosairaudet, toim. Kinnula V. Laitinen L.A.L, Tukiainen P. Kustannusosakeyhtiö Duodecim, 2000: