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Communications to the Editor |

Bird-Years as Well as Pack-Years FREE TO VIEW

Marc A. Judson; Steven A. Sahn
Author and Funding Information

Medical University of South Carolina, Charleston, SC

Correspondence to: Marc A. Judson, MD, FCCP, Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Allergy and Clinical Immunology, 96 Jonathan Lucas St, Charleston, SC 29425; e-mail: judsonma@MUSC.edu



Chest. 2004;125(1):353-354. doi:10.1378/chest.125.1.353-a
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To the Editor:

Although pulmonary physicians can make a difference for their patients, it is not often that they can cure their diseases. Asthma, COPD, and most interstitial lung diseases are chronic conditions that patients often have to endure for a lifetime. Patients usually have to be satisfied that their pulmonary symptoms can be “controlled” but not totally alleviated with the help of their pulmonologist.

It should excite us as pulmonologists that we can actually “cure” a disease that is potentially lethal. There is one such curable interstitial lung disease whose diagnosis does not even depend on sophisticated testing but is simply “established” by taking an adequate medical history. Failure to ask certain easy-to-answer questions can have catastrophic consequences to the point that the patient may acquire end-stage pulmonary fibrosis and respiratory failure.

The disease is hypersensitivity pneumonitis, and the questions involve exposure to organic aerosols, especially exposure to birds.12 Because the risk of hypersensitivity pneumonitis depends on the patient’s immune response and both the degree and duration of exposure, we determine the patient’s “bird-years.” Simply put, bird-years are determined by the number of birds and the years of bird exposure, as is done for pack-years of cigarette smoking. For example, if a person has four birds for 5 years or one bird for 20 years, they would both have accumulated 20 bird-years. Obviously not all bird exposures are identical. Cleaning of bird cages and walking through enclosed cages as pigeon breeders do would imply extremely high exposure to bird bioaerosols. Questions about whether the patient “owns pets” are not specific enough, as many patients do not consider birds as pets. Questions also need to be posed concerning exposure to water sources including humidifiers,3 hot tubs,4 and moldy environments.

Hypersensitivity pneumonitis can present as acute illness with rapid onset of fever, chills, dyspnea, and alveolar infiltrates on the chest radiograph.5 The disease may also present subacutely and resemble chronic bronchitis.5 Finally there is a chronic form of the disease in which dyspnea, lung restriction, and pulmonary fibrosis develop insidiously.5

The combination of restriction on pulmonary function tests, interstitial lung disease observed on high-resolution CT scans, and positive precipitins to avian or mold antigens strongly suggests the presence of hypersensitivity pneumonitis. BAL shows an average of 60% lymphocytes, with up to 90% in acute cases.6 However, without eliciting the appropriate medical history and determining bird-years, such a diagnostic workup is rarely undertaken. Furthermore, the precipitating antibody that leads to hypersensitivity pneumonitis is often not detected.7 Failure to ask these questions may lead to unnecessary lung biopsies and immunosuppressive treatment (instead of avoidance of the organic antigen). The final tragic result of chronic untreated hypersensitivity pneumonitis may be end-stage lung fibrosis and respiratory failure.

It has been estimated that the prevalence of bird fanciers’ lung among bird owners in Britain is between 0.5% and 7.5%. With such a large population at risk, a large number of individuals could be affected.8 So ask about bird-years as well as pack-years. It might really make a difference.

References

Hargreave, DJ, Pepys, J, Longbotton, JL, et al (1966) Bird breeder’s (fancier’s) lung.Lancet1,445-449
 
Sahn, SA, Richerson, HB Extremes of clinical presentation of parakeet fancier’s lung.Arch Intern Med1972;130,913-917
 
Baur, X, Behr, J, Dewair, M, et al Humidifier lung and humidifier fever.Lung1988;166,113-124
 
Rickman, OB, Ryu, JH, Fidler, ME, et al Hypersensitivity pneumonitis associated withMycobacterium avium complexand hot tub use.Mayo Clin Proc2002;77,1233-1237
 
Fink, JN, Sosman, AJ, Barboriak, JJ, et al Pigeon breeders’ disease.Ann Intern Med1968;68,1205-1218
 
Viosen, C, Tonnel, AB, Lahoute, C, et al Bird fancier’s lung: studies of broncho-alveolar lavage and correlation with inhalation provocation tests.Lung1981;159,17-22
 
Rose, C, King, TE Controversies in hypersensitivity pneumonitis.Am Rev Respir Dis1992;145,1-2
 
Hendrick, DJ, Faux, JA, Marshall, R Budgerigar-fancier’s lung: the commonest variety of allergic alveolitis in Britain.BMJ1978;2,81-84
 

Figures

Tables

References

Hargreave, DJ, Pepys, J, Longbotton, JL, et al (1966) Bird breeder’s (fancier’s) lung.Lancet1,445-449
 
Sahn, SA, Richerson, HB Extremes of clinical presentation of parakeet fancier’s lung.Arch Intern Med1972;130,913-917
 
Baur, X, Behr, J, Dewair, M, et al Humidifier lung and humidifier fever.Lung1988;166,113-124
 
Rickman, OB, Ryu, JH, Fidler, ME, et al Hypersensitivity pneumonitis associated withMycobacterium avium complexand hot tub use.Mayo Clin Proc2002;77,1233-1237
 
Fink, JN, Sosman, AJ, Barboriak, JJ, et al Pigeon breeders’ disease.Ann Intern Med1968;68,1205-1218
 
Viosen, C, Tonnel, AB, Lahoute, C, et al Bird fancier’s lung: studies of broncho-alveolar lavage and correlation with inhalation provocation tests.Lung1981;159,17-22
 
Rose, C, King, TE Controversies in hypersensitivity pneumonitis.Am Rev Respir Dis1992;145,1-2
 
Hendrick, DJ, Faux, JA, Marshall, R Budgerigar-fancier’s lung: the commonest variety of allergic alveolitis in Britain.BMJ1978;2,81-84
 
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