Topic Resources Hypersensitivity pneumonitis is a type of inflammation in and around the tiny air sacs (alveoli) and smallest airways (bronchioles) of the lung caused by a hypersensitivity reaction to inhaled organic dusts or, less commonly, chemicals. Dusts that contain microorganisms or proteins may cause a hypersensitivity reaction in the lungs. People may develop fever, cough, chills, and shortness of breath within 4 to 8 hours of re-exposure to substances to which they are sensitized. Doctors use chest computed tomography (CT) and tests of lung function to determine whether there is a problem with the lungs. The substance that is causing the reaction can sometimes be identified by using a blood test and, when the person is affected at work, an industrial hygiene specialist may analyze the workplace to identify triggering substances. People who work with substances that are likely to cause hypersensitivity reactions should use protective equipment, such as face masks, during work. People who can
avoid re-exposure usually recover, but they sometimes need to take corticosteroids to reduce lung inflammation. Many substances can cause hypersensitivity reactions in the lungs. Organic dusts that contain microorganisms or proteins, and chemicals, such as isocyanates, may cause hypersensitivity pneumonitis. Farmer's lung, which results from repeated inhalation of heat-loving (thermophilic) bacteria in moldy hay, is a well-known example of hypersensitivity pneumonitis. Bird fancier's lung is another example. It occurs when dust from the feathers of birds (either on living birds or in pillows and comforters) is inhaled.  Depending on how quickly symptoms develop, hypersensitivity pneumonitis may be
In acute hypersensitivity pneumonitis, people develop fever, cough, chills, and shortness of breath typically 4 to 8 hours after re-exposure to significant amounts of the causative organic dust. Wheezing is unusual. If people have no further contact with the antigen, symptoms usually diminish over a day or two, but complete recovery may take weeks. Subacute hypersensitivity pneumonitis develops more slowly. Cough and shortness of breath may develop and worsen over days or weeks. Sometimes symptoms may be so severe that people need to be hospitalized.
The diagnosis of hypersensitivity pneumonitis is based partly on symptoms, the clinical features, identification (if possible) of the dust or other substance causing the problem, as determined by what the person says, an analysis of the workplace by industrial hygiene specialists, the presence of antibodies on a blood test, or a combination. Occasionally, blood tests are needed to look for clues to the substance causing the hypersensitivity or to eliminate other possible causes. The best prevention is to avoid exposure to the antigen, but avoiding exposure may be impractical (for example, if the person cannot change jobs). Eliminating or reducing dust, wearing protective masks, and using good ventilation systems may help prevent both sensitization and recurrence. However, even the best prevention methods may not be effective.
People who have an acute episode of hypersensitivity pneumonitis usually recover if further contact with the substance is avoided. If the episode is severe, corticosteroids, such as prednisone, reduce symptoms and may help reduce severe inflammation. Prolonged or recurring episodes may lead to irreversible disease and progressive disability and requires long-term immunosuppression. CLICK HERE FOR THE PROFESSIONAL VERSION Copyright © 2022 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved. These substances are called allergens, and the most common are proteins in pollen from trees and grasses, food, fur, dust mites or mould, in addition to metals and substances used in cosmetics and pharmaceuticals. An allergic reaction is an overreaction of the immune system to an allergen. Allergy development takes place in two stages, with an initial sensitisation or induction phase followed by an effector phase (see figure below). Clinical symptoms of allergy only appear in the effector phase. Some people do not progress from the induction phase and will therefore not present clinical symptoms of allergy. The figure shows the phases of allergy development Food allergyFood allergy is a significant public health problem and is reported to affect 3-4% of adults and 6-8% of children in Europe, with an increasing incidence among children. Changes in eating habits, with new imported products, more processed foods and increased travel can also have contributed to food reactions becoming more common. Food allergy occurs most often in those who have atopic diseases, such as atopic dermatitis, asthma and hay fever. Allergy is defined as an immunological response and is limited to food reactions that can be confirmed by immunological methods such as the detection of IgE antibodies in serum. Food allergies are triggered by food proteins and usually cause quick reactions. These reactions occur because the natural tolerance is broken. Symptoms are commonly seen in other organs than the stomach and intestines, such as the skin, the respiratory system and the cardiovascular system. Hypersensitivity reactions generally cause intestinal symptoms. Common food allergens include legumes such as peanuts and nuts, flour, fish and shellfish. Cow's milk, wheat and eggs often trigger allergies among children, but they usually grow out of these allergies by school age. The incidence of severe reactions to food in Norway is unknown. In 2000, the National Register of Severe Allergic Reactions to Food was established to increase knowledge, and doctors have been encouraged to report severe patient reactions. As from January 1st 2018 the Register is no longer in operation. Respiratory allergyRespiratory allergies are caused by proteins in the air that are inhaled and trigger airway inflammation. They may be due to specific allergic reactions, or more general reactions to irritants such as smoke and fumes in the indoor and outdoor environment that can aggravate allergy symptoms. There are many sources of respiratory allergies; house dust contains various components such as dust mites, pet allergens, pollen and particulates that can trigger asthma and allergies. If humidity is too high, mould growth can occur, and the amount of mould spores containing allergens will increase. House dust mites thrive wherever it is hot and humid, especially in mattresses and bedding. Mite faeces are the main cause of allergies. Pet allergens usually come from proteins from animal skin, fur, urine and saliva. The allergens often sit on small particles that can stay aloft for a long time and thus spread over large areas. The increase in allergic diseases may be related to climate change. A warmer climate leads to a longer pollen season and therefore an increased incidence of respiratory allergies. Pollen can cause cross-allergies because there are similar proteins in pollen and plant foods such as fruits, vegetables and nuts, which will also increase allergic reactions to food. Cross allergies, however, cause milder symptoms than primary allergies. Skin allergyThere are several different types of skin allergies such as allergic contact dermatitis, urticaria (hives) and photoallergy. Clinical symptoms for allergic contact dermatitis often occur 1-2 days after exposure to an allergen. Photoallergy symptoms may occur somewhat earlier than allergic contact dermatitis. Urticaria often occurs within minutes after exposure. The most common causes of skin allergies are exposure to metals and chemicals that can penetrate the skin, but proteins may also cause skin allergy. These substances are present in consumer products such as cosmetics and body care products, hair dyes, detergents, textiles and jewellery. The most common contact allergens are nickel, fragrances and thimerosal (preservative). Approximately 20% of the population has a contact allergy. Certain occupational groups are particularly vulnerable to developing skin allergies. These are professions with frequent hand washing and work with irritant and sensitising agents (e.g. rubber chemicals, fragrances, preservatives, dyes, metals). Atopic dermatitis (sometimes called infantile eczema) is a chronic disease with an itchy rash that often appears in early childhood. About 70% of children with atopic eczema grow out of it before adolescence. The trigger factors are unclear, but children with allergic and asthmatic parents have an increased risk of developing atopic dermatitis. A combination of genes and environment seems to be important. Cosmetic allergyUndesirable effects from the use of cosmetic products often occur. These include soap, shampoo, moisturisers, deodorants, shaving products and make-up. Undesirable effects include allergies, rashes, blisters, burning or other symptoms. The products that cause most problems are fragrances, preservatives and hair dyes. Preservatives and fragrances can cause adverse effects, particularly in the form of rashes and other skin reactions.
What respiratory disorder is caused by a sensitivity to an allergen?Learn About Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis happens when you breathe in specific substances (allergens) that cause your body to have an allergic reaction. This is commonly an occupational disease that can be treated by avoiding exposure to the allergen.
What do you call a chronic inflammatory disease of the airways?A chronic inflammatory disorder of the airways. Airway inflammation is associated with airway hyper-responsiveness, airflow limitation, and respiratory symptoms.
What causes inflammation of the airway?Airway inflammation is another important factor in the production of increased airway responsiveness. Inflammation may occur as a result of either immunologic or nonimmunologic airway insults, which produce airway edema and cause the immigration of inflammatory cells into the lumen through the epithelium.
Which disorder is an inflammation of the bronchial airways?Bronchitis is inflammation of the breathing tubes (bronchi). There are several types of bronchitis, but the most common are acute and chronic. Chronic bronchitis is often part of chronic obstructive pulmonary disease (COPD). This is a group of lung diseases that cause airflow blockage and breathing problems.
|
Which condition is a chronic inflammatory disorder of the airway usually caused by sensitivity to an allergen?
Urheberrechte © © 2024 IlerngutCOM Inc.
