When we breathe in, we deliver air to our lungs, but we also take in small amounts of other molecules. Some of these can cause allergic reactions in people’s lungs. The molecules that cause this are very varied and include fungal spores and bird dander. The reactions are not normally dangerous but repeated exposure can cause scarring to the lungs, known as fibrosis, which causes breathing difficulties that we cannot treat effectively. Recently these reactions have been linked to the death of a man after he reacted to the mould in his bagpipes and to the use of e-cigarettes. Unfortunately, different people react to different allergens and have different symptoms, and it is difficult to tell that this reaction is the cause of their symptoms unless we already know the molecule at fault.

In this study, we looked into whether we could use a blood test to identify which members of an at-risk group of bird keepers were experiencing symptoms of these reactions. None of the participants had an existing diagnosis of either the allergy or fibrosis. We found that our test more accurately predicted the presence of symptoms than the previous test that could only show exposure to the allergen, not the presence of a reaction. This could provide the basis for a simple blood test that could be used to diagnose these allergic reactions and allow somebody to limit their exposure to the allergen before it irreversibly damages their lungs.