Reed et al. were the first to diagnose pigeon breeder’s lung [12].
A noninvasive testing like antigen exposure, recurrent symptoms after exposure, inspiratory crepitations, and weight loss could have a high probability of 98% of diagnosing HP, so BAL or lung biopsy would be unnecessary for the confirmation especially with consistent HRCT findings [13].
In the present study, all the diagnosed subjects gave a significant history of exposure to pigeons. The mean age was 38.12 ± 13.07 which is younger than most previous studies. In a large Spanish study of 86 BFL [5], the mean age was 47 years.
Moreover, Selman et al. [14] reported similar results where the mean age of BFL patients was 49 years.
The close contact to birds of which sweeping is the most prominent feature in Egypt could be considered one prominent factor of rapid and early onset of the disease, so the presentation occurs at younger age.
High proportion of disease among females is anticipated as they spent more time at home. In confirmation of that, the current study found that 56 (83.6%) of patients were females. Several studies found the same finding [5, 10, 14]. Also, in our community, women are usually more concerned with caring and sweeping for birds as a part of their daily activities.
As regards smoking history, 58 (86.6%) of our patients were nonsmokers. This could be attributed to the predominance of females in the current study where smoking habit is rare in Egyptian community. Similarly, Selman et al. reported that 83% of BFL were never-smokers [13]. Also, in a large Spanish study, 78% of BFL patients were non-smokers [5]. The incidence of HP in non-smokers is higher than smokers, as smokers had a lower level of expression of immunostimulatory molecules such as peripheral membrane protein B7 on their alveolar macrophages [15].
As shown in the results, most patients were not exposed to biomass fuel and this can be explained in two ways, first is the decreased use of biomass fuel in general in our community and the other may be the same biologic effect of smoking on macrophages. Hirschmann et al. [16] reported that heredity may play an important role in HP, with families positive for HLA-DR7, HLA-B8, and HLA-DQw3 showing a stronger predisposition.
We also found that 7.7% of patients had a positive family history of HP. As regards the clinical manifestation of HP in our study, 63 patients (94%) presented with dyspnea, and 65 (97%) patients presented with cough. Physical examination revealed crackles in 58.2% of patients. Finger clubbing was observed in 6% of patients. In the same line, Morell et al. [5] found that 98% of patients presented with dyspnea, 82% presented with cough, and only 7% had finger clubbing. Contrary, Sansores et al. [17] found a larger percentage (51%) of clubbing in BFL.
A restrictive pulmonary function is almost the case in BFL, but sometimes, patients had normal pulmonary functions after resolution of acute stage [18].
In the present study, 9 (14.3%) had normal pulmonary functions.
Tsutsui et al. [19] found a more rapid deterioration in clinical and functional state in BFL cases exposed to a higher concentration of avian antigens collected from their household environments. This gives a clear explanation for two significant findings in the present study which are as follows: first, the more rapid onset of symptoms after the onset of exposure in patients who were exposed to pigeons in closed areas than those breeding in open areas (p value 0.01), and second, the significant reduction in FVC%, O2 saturation, increase in dyspnea grade, and more rapid onset of symptoms after exposure in patients who had a history of sweeping for birds (p value 0.02, 0.01, 0.04, and 0.008 respectively) which is also a common habit in our community.
