Question: What is (are) Hypersensitivity Pneumonitis ?
Answer: Hypersensitivity pneumonitis (noo-mo-NI-tis), or HP, is a disease in which the lungs become inflamed from breathing in foreign substances, such as molds, dusts, and chemicals. These substances also are known as antigens (AN-tih-jens). People are exposed to antigens at home, while at work, and in other settings. However, most people who breathe in these substances don't develop HP. Overview To understand HP, it helps to understand how the lungs work. When you breathe, air passes through your nose and mouth into your windpipe. The air then travels to your lungs' air sacs. These sacs are called alveoli (al-VEE-uhl-eye). Small blood vessels called capillaries run through the walls of the air sacs. When air reaches the air sacs, the oxygen in the air passes through the air sac walls into the blood in the capillaries. The capillaries connect to a network of arteries and veins that move blood through your body. In HP, the air sacs become inflamed and may fill with fluid. This makes it harder for oxygen to pass through the air sacs and into the bloodstream. The two main types of HP are acute (short-term) and chronic (ongoing). Both types can develop as a result of repeatedly breathing in an antigen. Over time, your lungs can become sensitive to that antigen. If this happens, they'll become inflamed, which can lead to symptoms and may even cause long-term lung damage. With acute HP, symptoms usually occur within 29 hours of exposure to an antigen you're sensitive to. Acute HP can cause chills, body aches, coughing, and chest tightness. After hours or days of no contact with the antigen, symptoms usually go away. If acute HP isn't found and treated early, chronic HP may develop. Symptoms of chronic HP occur slowly, over months. Chronic HP can cause a worsening cough, shortness of breath with physical activity, fatigue (tiredness), and weight loss. Severe HP may cause clubbing (a widening and rounding of the tips of the fingers or toes). With chronic HP, symptoms may continue and/or worsen, even after avoiding the antigen. Sometimes, chronic HP can cause long-term lung damage, such as pulmonary fibrosis (PULL-mun-ary fi-BRO-sis). This is a condition in which tissue deep in your lungs becomes scarred over time. Outlook Avoiding or reducing your contact with antigens can help prevent and treat HP. For example, cleaning heating and ventilation filters can help reduce your contact with mold. Wetting compost prior to handling it can reduce contact with harmful dust. If HP is caught early, avoiding the antigen that caused it may be the only treatment you need. If you have chronic HP, your doctor may prescribe medicines to reduce lung inflammation. Researchers continue to study why some people develop HP after being exposed to antigens, while others don't. They're also looking for better ways to quickly pinpoint which antigens are causing HP in people who are believed to have the disease.
Source: NHLBI

Question: What causes Hypersensitivity Pneumonitis ?
Answer: Repeatedly breathing in foreign substances can cause hypersensitivity pneumonitis (HP). Examples of these substances include molds, dusts, and chemicals. (Mold often is the cause of HP.) These substances also are known as antigens. Over time, your lungs can become sensitive to antigens. If this happens, your lungs will become inflamed, which can lead to symptoms and may even cause long-term lung damage. Antigens may be found in the home, workplace, or in other settings. Antigens can come from many sources, such as: Bird droppings Humidifiers, heating systems, and hot tubs Liquid chemicals used in the landscaping and florist industries Moldy hay, straw, and grain Chemicals released during the production of plastics and electronics, and chemicals released during painting Mold released during lumber milling, construction, and wood stripping
Source: NHLBI

Question: Who is at risk for Hypersensitivity Pneumonitis? ?
Answer: People who repeatedly breathe in foreign substances are at risk for hypersensitivity pneumonitis (HP). These substances, which also are known as antigens, include molds, dusts, and chemicals. However, most people who breathe in these substances don't develop HP. People at increased risk include: Farm and dairy cattle workers People who use hot tubs often People who are exposed to molds or dusts from humidifiers, heating systems, or wet carpeting Bird fanciers (people who keep pet birds) and poultry handlers Florists and landscapers, especially those who use liquid chemicals on lawns and gardens People who work in grain and flour processing and loading Lumber milling, construction, wood stripping, and paper and wallboard workers People who make plastics or electronics, and those who paint or work with other chemicals
Source: NHLBI

Question: What are the symptoms of Hypersensitivity Pneumonitis ?
Answer: Signs and symptoms of hypersensitivity pneumonitis (HP) depend on whether the disease is acute (short-term) or chronic (ongoing). Acute Hypersensitivity Pneumonitis With acute HP, symptoms usually occur within 29 hours of exposure to an antigen you're sensitive to. (An antigen is a substance that your body reacts against, such as molds, dusts, and chemicals.) Acute HP can cause chills, body aches, coughing, and chest tightness. After hours or days of no contact with the antigen, symptoms usually go away. Chronic Hypersensitivity Pneumonitis If acute HP isn't found and treated early, chronic HP may develop. With chronic HP, symptoms occur slowly, over months. Chronic HP can cause a worsening cough, shortness of breath with physical activity, fatigue (tiredness), and weight loss. Some symptoms may continue and/or worsen, even after avoiding the antigen. Chronic HP can cause long-term lung damage, such as pulmonary fibrosis. This is a condition in which tissue deep in your lungs becomes scarred over time. Clubbing also may occur if HP is severe. Clubbing is the widening and rounding of the tips of the fingers or toes. A low level of oxygen in the blood causes this condition.
Source: NHLBI

Question: How to diagnose Hypersensitivity Pneumonitis ?
Answer: To diagnose hypersensitivity pneumonitis (HP), your doctor must pinpoint the antigen that's causing the disease and its source. (An antigen is a substance that your body reacts against, such as molds, dusts, and chemicals.) Your doctor will ask you detailed questions about: Your current and past jobs Your hobbies and leisure activities The types of places where you spend time Your exposure to damp and moldy places Your doctor also will do a physical exam and look at test results to diagnose HP. Physical Exam During the physical exam, your doctor will ask about your signs and symptoms, such as coughing and weight loss. Your doctor also will look for signs of HP. For example, he or she will listen to your lungs with a stethoscope for abnormal breathing sounds. HP can cause a crackling sound when you breathe. Your doctor also may look for signs of pulmonary fibrosis, a possible complication of chronic (ongoing) HP. Pulmonary fibrosis is a condition in which tissue deep in your lungs becomes scarred over time. Your doctor also may check for clubbing. Clubbing is the widening and rounding of the tips of the fingers or toes. A low level of oxygen in the blood causes this condition. Diagnostic Tests and Procedures To help diagnose HP, your doctor may recommend or more of the following tests or procedures. Chest X Ray or Chest Computed Tomography (CT) Scan A chest x ray and chest CT scan create pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. These pictures can show signs of HP. Lung Function Tests Lung function tests measure how much air you can breathe in and out, how fast you can breathe air out, and how well your lungs can deliver oxygen to your blood. One of these tests is spirometry (spi-ROM-eh-tre). During this test, a technician will ask you to take a deep breath. Then, you'll blow as hard as you can into a tube connected to a small machine. The machine is called a spirometer. The machine measures how much air you breathe out. It also measures how fast you can blow air out. Pulse Oximetry This test measures the amount of oxygen in your blood. A small sensor is attached to your finger or ear. The sensor uses light to estimate how much oxygen is in your blood. Precipitin Test This blood test looks for antibodies (proteins) that your body creates in response to antigens. The presence of these proteins may suggest HP. Challenge Test During this test, you're re-exposed to the suspected antigen. Then, you'll be watched for signs and symptoms of HP. Bronchoscopy For bronchoscopy (bron-KOS-ko-pee), your doctor passes a thin, flexible tube through your nose (or sometimes your mouth), down your throat, and into your airways. At the tip of the tube are a light and mini-camera. This allows your doctor to see your windpipe and airways. Your doctor may insert forceps (a device used to grab or hold things) through the tube to collect a tissue sample. You'll be given medicine to make you relaxed and sleepy during the procedure. Bronchoalveolar Lavage During bronchoscopy, your doctor may inject a small amount of salt water (saline) through the tube into your lungs. This method is called bronchoalveolar lavage (BRONG-ko-al-VE-o-lar lah-VAHZH). This fluid washes the lungs and helps bring up cells from the airways and the area around the air sacs. Your doctor will look at these cells under a microscope. Surgical Lung Biopsy To confirm a diagnosis of HP, your doctor may do a surgical lung biopsy. Your doctor can use a biopsy to rule out other causes of symptoms and check the condition of your lungs. For a surgical lung biopsy, your doctor takes samples of lung tissue from several places in your lungs. He or she then looks at them under a microscope. Your doctor may use one of the following methods to get lung tissue samples. Video-assisted thoracoscopy (thor-ah-KOS-ko-pee). For this procedure, your doctor inserts a small, lighted tube with a camera (endoscope) into your chest through small cuts between your ribs. The endoscope provides a video image of your lungs and allows your doctor to collect tissue samples. This procedure is done in a hospital. You'll be given medicine to help you sleep through the procedure. Thoracotomy (thor-ah-KOT-o-me). For this procedure, your doctor removes a few small pieces of lung tissue through a cut in the chest wall between your ribs. Thoracotomy is done in a hospital. You'll be given medicine to help you sleep through the procedure.
Source: NHLBI

Question: What are the treatments for Hypersensitivity Pneumonitis ?
Answer: The best way to treat hypersensitivity pneumonitis (HP) is to avoid the antigen that caused it. (An antigen is a substance that your body reacts against, such as molds, dusts, and chemicals.) In acute (short-term) HP, symptoms usually go away once you're no longer in contact with the antigen. In chronic (ongoing) HP, you may need medicines to relieve your symptoms. People who have chronic HP may develop pulmonary fibrosis. This is a condition in which tissue deep in your lungs becomes scarred over time. People who have this condition may need further treatment, such as oxygen therapy and pulmonary rehabilitation (rehab). Avoiding Antigens Once the antigen that caused the HP and its source are found, you can take steps to avoid it. If HP is caught early, avoiding the antigen may be the only treatment you need. Avoiding an antigen may be easier at home than at work. For example, if your pet bird, moldy carpet, or hot tub is the source of the antigen, you can remove it from your home. If your heating system is the source of the antigen, you can have your system properly serviced. However, if the antigen is at work, you may need to talk with your supervisor about your condition and ways to protect yourself. For example, masks or personal respirators may help protect you from antigens in the air. (A personal respirator is a device that helps filter the air you breathe in.) Some people who have HP may need to move to a different home or change jobs to avoid antigens. After hurricanes, for example, some people have to move from their homes to avoid molds that could harm their lungs. However, moving and changing jobs sometimes isn't possible. Medicines and Other Treatments If you have chronic HP, your doctor may prescribe medicines called corticosteroids. These medicines reduce lung inflammation. Prednisone is an example of a corticosteroid. Long-term use of prednisone, especially at high doses, can cause serious side effects. Thus, if your doctor prescribes this medicine, he or she may reduce the dose over time. Examples of side effects from corticosteroids are increased risk of infections, high blood pressure, high blood sugar, and osteoporosis (thinning of the skin and bones). People who develop pulmonary fibrosis may need medicines, oxygen therapy, and/or pulmonary rehab. Pulmonary fibrosis is a condition in which tissue deep in your lungs becomes scarred over time. If you smoke, try to quit. Smoking can make HP symptoms worse and lead to other lung diseases. Talk with your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke.
Source: NHLBI