Hypersensitivity pneumonitis

• Farmer’s lung. This is caused by breathing in mould that grows on hay, straw and grain. 
• Bird fancier’s lung. This is caused by breathing in particles from feathers or bird droppings. 
• The disease can also develop from inhaling fungus in humidifiers, heating systems, and air-conditioners found in homes and offices, especially if they are not well maintained. 
• Sometimes no obvious cause can be found.

Symptoms of cough, shortness of breath and sometimes fever or flu-like symptoms can occur suddenly after you’ve been exposed. This is the acute form of the condition and can go away without causing permanent damage to the lungs, if the substance that caused the attack can be permanently avoided.

In other cases, symptoms of cough and breathlessness can come on more gradually, perhaps over months or years; following repeated exposure to a particular substance. This can cause permanent scarring or fibrosis of the lungs. This is called fibrotic hypersensitivity pneumonitis and often a specific cause cannot be found.

Your specialists will take a detailed medical history and perform a thorough physical examination. You may be asked to have the following investigations:

• Lung function tests: These are breathing tests which see how well your lungs are working. These can be used to monitor your lung disease and also to see whether it is responding to treatment.
• CT scan of your chest: This shows a detailed picture of your lungs. There are characteristic patterns on these pictures that can help your specialist work out whether the disease is active or quiet. to identify either scarring or inflammation of lung tissue. 
• Blood tests are performed to detect certain proteins in blood for example bird proteins in bird fancier’s lung or moulds in farmer’s lungs.
• Some people may also have a bronchoscopy, where a small flexible tube is passed down into your lungs, allowing collection of cells which may help with diagnosis.
• Finally, if the diagnosis is not clear after these tests, your doctor might talk to you about a lung biopsy, a surgical test, to confirm the diagnosis. 
   

If we can find and remove the cause, people with early hypersensitivity pneumonitis should make a full recovery. However, there symptoms will often return if exposed in the future. 

For people with more chronic (long-term) disease, removal of the trigger hopefully stops the disease getting worse, although unfortunately this is not always the case. Your doctor may advise some treatments to try to slow or stop the disease getting worse (see below).

If we can identify a specific cause, the most important part of treatment is to try to avoid it. This may mean rehoming household pets, changing your job, or using a special mask when exposed. If you can’t stop exposure this increases the chance that the condition will progress to irreversible lung scarring (or fibrosis).

Your doctor may advise a trial of specific medications like the ones below. 

Medications 

Steroids are produced naturally in the body by the adrenal gland. And additional steroid called prednisolone can be given to try to reduce inflammation in some patients. They are usually given in tablet form but may be given by injection into a vein. If you are prescribed steroid tablets on a long-term basis, you should not stop them suddenly. You will be given a ‘steroid emergency card’ which you should always carry with you. Your specialist may also check if you need treatment against some side effects of steroids such as bone protection medication and anti-reflux treatment. 

Immunosuppressive medication is commonly used to dampen down the immune response in the lungs. Some examples of these medications are cyclophosphamide, mycophenolate mofetil and azathioprine. One of these medications will usually be prescribed alongside a steroid (such as prednisolone). It can allow the dose of the steroid to be reduced and in some cases, may allow the steroids to be stopped altogether. As a result, they are sometimes also called ‘steroid sparing agents’. Whilst you are taking immunosuppressant medication you will require regular blood tests to monitor your response to the treatment.

If your condition gets worse despite taking a steroid and/or immunosuppressive medication, your specialist may suggest an antifibrotic medication that aims to slow further progression. Other medications and therapies can help symptoms such as cough and breathlessness. Your specialist will discuss options with you.

Other treatments

Pulmonary rehabilitation is an exercise and education programme that can help you to learn to manage your breathlessness and remain active. The programmes are multidisciplinary, meaning that the team includes respiratory physiotherapists, nurses, dieticians, doctors and others, and can help improve energy, strength, and your quality of life.

Supplemental oxygen: As lung scarring can reduce the amount of oxygen getting from your lungs into the bloodstream, some individuals may require oxygen therapy. If your oxygen levels are low, oxygen therapy may help with breathlessness and help you to be more active. Correct levels of oxygen in the blood are necessary for normal body functions and reducing additional health problems.

Clinical trials: You can ask about clinical trials which test new treatments. Joining is voluntary. 

Lung transplantation: A small minority of patients may require assessment for and be suitable for lung transplantation.

• Have your seasonal vaccinations (COVID-19 and flu) and the pneumonia vaccination (only once). 
• You may be eligible for benefits like PIP (Personal Independence Payment) if you need help with personal care or getting about. 
• Our specialist nurses runs a regular Pulmonary Fibrosis Support Group which is a space for discussion with other patients with similar lung conditions. Here we also aim to have presentations from a variety of guest speakers and charities.
• Keep active and do what you enjoy!

Action for Pulmonary Fibrosis

Asthma and Lung UK