Why India needs to rethink its love for pigeons

When Dr Bobby Bhalotra meets a patient with a persistent dry cough and breathlessness and no other symptoms, he first asks them about their occupational history. Are they farmers or involved in the poultry business? Do they work with soldering or in the cotton or fabric industry? If the patient answers in the negative, the Delhi-based pulmonologist asks: do they have pigeons in their balconies, on their air conditioning units or in shafts in their buildings? Do they, perhaps, frequently feed pigeons?

Often, Bhalotra finds that the patient has a history of exposure to the birds. His medical team then conducts a test to check for possible damage to lung function. They also do X-ray or CT scans that can reveal any patches on the lungs, and a blood test that confirms if the patient has been exposed to various agents, including fungus, moulds, dampness of walls and pigeon droppings.

When the medical investigation reveals permanent damage to the patient’s lungs, the disease is more often than not hypersensitivity pneumonitis, also known by the name bird fancier’s lung, which uses a term for bird enthusiasts. The disease causes lung scarring, tightness in the chest, shortness of breath and prolonged cough.

Hypersensitivity pneumonitis “is not an infection...