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Abstract:
The skin test with hay extract or with Micropolyspora faeni (MF), is not commonly used in the diagnosis of Farmer's lung (FL), as it is not considered specific. In our study, we have applied the intracutaneous test with these antigens in 26 patients affected with FL; 18 of them were still in contact with the antigen and the remaining eight had not been in contact with the hay during the previous year. Twenty-five asymptomatic farmers (AF) served as a control group. In the first group and with hay extract, the immediate reading (I) was positive in 15 of 18 (83.3 percent), the late reaction (L) in 18 of 18 (100 percent), and the delayed one (D) in eight of 18 (44.4 percent). In the 25 AF, the results were as follows: I, seven of 85 (28 percent); L, 17 of 25 (68 percent); and D, one of 25 (4 percent). Consequently, the differences between both groups were significant: I, p less than 0.01; L, p less than 0.05; and D, p less than 0.01. Using MF as an antigen, the test is somewhat less effective: p less than 0.02, p less than 0.02, and p less than 0.2, respectively. These results suggest that the intradermal injection with hay extract is an easy, effective test in the diagnosis of FL, and at the same time, a better means of distinguishing FL patients from AF than the precipitation test.
Insights
Intradermal skin testing with hay extract is an effective diagnostic tool for Farmer's lung (FL). This method better distinguishes FL patients from asymptomatic farmers compared to precipitation tests.
Area of Science:
- Pulmonary Medicine
- Immunology
- Occupational Health
Background:
- Farmer's lung (FL) diagnosis traditionally lacks specific skin testing methods.
- Current diagnostic approaches for FL may not always provide clear differentiation.
- Micropolyspora faeni (MF) and hay extract are known antigens associated with FL.
Purpose of the Study:
- To evaluate the diagnostic efficacy of intracutaneous testing with hay extract and MF in Farmer's lung patients.
- To compare the specificity and sensitivity of intradermal testing against precipitation tests for FL diagnosis.
- To assess the utility of immediate, late, and delayed skin reactions in differentiating FL patients from asymptomatic farmers.
Main Methods:
- Intracutaneous skin tests were performed on 26 FL patients (18 with ongoing antigen exposure, 8 without) and 25 asymptomatic farmers (AF) as controls.
- Antigens used included hay extract and Micropolyspora faeni (MF).
- Immediate (I), late (L), and delayed (D) skin reactions were recorded and analyzed for significance.
Main Results:
- Hay extract elicited significant differences between FL patients and AF: immediate (83.3% vs 28%, p<0.01), late (100% vs 68%, p<0.05), and delayed (44.4% vs 4%, p<0.01) reactions.
- MF antigen showed less effectiveness but still significant differences for immediate (p<0.02) and late (p<0.02) reactions.
- Intradermal testing with hay extract demonstrated superior diagnostic capability compared to precipitation tests.
Conclusions:
- Intradermal injection with hay extract is a simple and effective diagnostic test for Farmer's lung.
- This skin test provides a more reliable method for distinguishing FL patients from asymptomatic farmers.
- Hay extract intradermal testing offers a valuable alternative or adjunct diagnostic tool in suspected FL cases.