About extrinsic allergic pneumonia

What is extrinsic allergic pneumonia?

Extrinsic Allergic Pneumonia, also known as Allergic Interstitial Pneumonitis, Hypersensitivity Pneumonitis, is a kind of inflammatory syndrome, more specifically, a lung disorder. Breakdown of the nameExtrinsic: origin is an outside matter – antigen.

Allergic: An allergic reaction from the antigen is the cause.

Pneumonia: inflammation within the lungs.

There are variations in the syndrome depending upon the antigen and the amount of exposure. The exposure of antigen can be domestic or industrial depending on the environment. The cause of Extrinsic allergic pneumonia is the continuous inhalation of antigens like dust, bacteria, chemicals, bird feathers or droppings, bioaerosol, etc. These antigens induce an allergic reaction and thus result in inflammation within the lungs (pneumonitis) in alveoli and small airways (bronchioles). Types of Extrinsic allergic pneumonia:

Extrinsic allergic pneumonia differentiates based on the kinds of antigens provoking the syndrome. There are around 200 antigens observed till date, some of them are discussed below. The most common types of Extrinsic allergic pneumonia are Bird Fancier’s Lung and Farmer’s lung.

1. Bird fancier's lung, bird breeder's lung, pigeon breeder's lung, and poultry worker's lung have Avian proteins as antigen. It results from exposure to feathers and bird droppings.

2. Chemical worker's lung–Isocyanate HP has Toluene Diisocyanate (TDI), Hexamethylene Diisocyanate (HDI), or Methylene bisphenyl isocyanate (MDI) as Antigens. This results from exposure to paints, resins, and polyurethane foams.

3. Coffee worker's lung has coffee bean protein as antigen. A person suffers from it upon prolonged exposure to coffee bean dust.

4. Compost Lung has Aspergillus as an allergen and is caused due to exposure to compost.

5. Detergent worker's disease, as the name suggests, emerges due to detergent exposure. Bacillus subtilis enzymes are the antigen.

6. Farmer's lung has two antigens moulds - Aspergillus species and bacteria - Thermophilic actinomycetes, Thermoactinomyces vulgaris, Saccharopolyspora Rectivirgula, Absidia Corymbifera, Eurotium Amstelodami. Farmers are at high risk when exposed to moldy hay.

7. Japanese summer house HP or Japanese summer-type HP results from continuous exposure to damp wood and Japanese mats called Tamai. The antigen's name is Trichosporon Cutaneum.

8. Laboratory workers' lung develops due to laboratory rats where male rat urine protein acts as an antigen for the body.

9. In Miller's lung, Sitophilus Granarius (wheat weevil) is the antigen, which enters the body when the person is under the exposure of dust-contaminated grain.

10. For Tap water HP, the antigen is yet unknown but results from exposure to contaminated tap water

What are the symptoms for extrinsic allergic pneumonia?

Extrinsic Allergic Pneumonia is the lung inflammation due to an allergic reaction caused by antigens present n the environment. Generally, a person with Extrinsic Allergic Pneumonia suffers difficulty in breathing, dry coughs, sweating, chills, ache, fatigue, and wheezing. The important thing to know is that not all patients show signs and symptoms of Extrinsic Allergic Pneumonia. There must be prolonged and continuous exposure to antigens or allergens. Variations in the syndrome symptoms depend upon the kind of antigen and amount of exposure - Acute, Subacute, Chronic.

Acute - The symptoms of Acute Extrinsic Allergic Pneumonia are headache, dyspnea, cough, rashes, swelling, tightness in the chest, fever, malaise, and chills. These may occur after 4-6 hours of exposure to the antigen or allergen. Sensitised people having a high level of antigen exposure are at high risk.

Subacute - The symptoms of Subacute Extrinsic Allergic Pneumonia are fatigue, cough, anorexia, dyspnea, pleurisy, and weight loss. However, these symptoms are less severe than Acute Extrinsic Allergic Pneumonia but last longer. These symptoms develop after days to weeks of antigen exposure.

Chronic - The symptoms of Chronic Extrinsic Allergic Pneumonia are cough, Rales (crackling sound while breathing), fever, Cyanosis (blue coloured skin appearance), progressive dyspnea, tachypnea, and maybe, expectoration of Blood 3. These occur after months to years of antigen exposure; farmers or animal caretakers are at high risk. In serious cases, patients may develop pulmonary fibrosis, which can cause respiratory failure, right heart failure, or even both. 

What are the causes for extrinsic allergic pneumonia?

Extrinsic allergic pneumonia, also known as Hypersensitivity pneumonia, is a type of lung inflammation that occurs when an individual is exposed to antigens, resulting in a hypersensitivity reaction leading to inflammation of lung tissue. These substances trigger an allergic immune reaction that blocks the alveoli and bronchiole.Its symptoms include fatigue, shortness of breath, cough, difficulty in breathing, weight loss, fever, chest tightness, chills, etc. There are many causes of extrinsic allergic pneumonia, and all of them are listed below:Airborne pollutants like airborne moles can cause this disorder, A variety of molds and bacteria also cause extrinsic allergic pneumonia. The occupational setting is a major factor that is related to this disorder. People who are exposed to animal dust, associated with birds, and involved in the manufacturing of cheese, sugar, etc. are exposed to certain irritations that can cause this disorder. Studies have shown that exposure to birds and their excreta is also one of the causes of this lung inflammation. Radiation therapy for the lungs, chest or full body can also result in developing hypersensitivity pneumonia. Farmers and workers involved in the agriculture field often inhale a mold growing on hay and grass, which leads to the development of pneumonitis. This condition is specially called a farmer's lung. Contaminated humidifiers at home, heating systems, and indoor hot tubs lead to breathing bacteria that often cause this lung issue. Exposure to bioaerosols and other chemicals for a prolonged period in the plastic and paint industry also leads to the development of this lung disorder.

What are the treatments for extrinsic allergic pneumonia?

Extrinsic allergic pneumonitis or extrinsic allergic alveolitis is a lung disorder that can affect an individual upon excessive inhalation of irritants like organic dust in a specific setting. Respiratory symptoms like fever, sneezing, wheezing, and irritation in the throat and nostrils are common in the acute stage. The chronic form of the disease is attributed to gradual degenerative issues and changes in the lung tissue combined with other respiratory problems like asthma. The treatments available for the disease are as follows:

1. The primary stage of treatment is the identification of the allergen responsible. This is necessary for the patient to initiate preventive measures to avoid redundant problems that might cause further deterioration in health.

2. Corticosteroid drugs may be administered in case of persisting symptoms despite avoidance. In acute cases, the use of steroids with preventive measures and adequate awareness can help keep the severity of the symptoms in check.

3. Consulting a pulmonologist for the corresponding treatment can become necessary in case of chronic respiratory ailments like asthma and bronchitis when combined with extrinsic allergic pneumonitis.

4. Doing regular checks and breathing exercises can help. Getting a pulmonary capacity test and chest scans can be necessary to detect the level and stage of damage caused to the lungs. Most of the time, an early diagnosis can help an individual keep the severity of symptoms under control without any invasive medical intervention. However, in the case of chronic stages of infection and degeneration in the lung tissues, it might become difficult for the patient to recover as easily even through treatment, thus making it important for one to know allergens that might pose a threat to their bodies and systems. Consulting an immunologist in case of redundant and frequent cases of allergic rhinitis can help prevent severe problems. 

What are the risk factors for extrinsic allergic pneumonia?

Extrinsic allergic pneumonia is a disorder that mainly affects the lungs and lung tissue. Produced as the result of an allergic immune reaction, this is caused by a variety of substances, especially mold and bacteria in the agriculture, bird, plastic, paint, and mushroom farming industry. Other causes include prolonged exposure to allergens that trigger an allergic response. Following are the risk factors for extrinsic allergic pneumonia: Certain occupations increase the risk of developing extrinsic allergic pneumonia. These include poultry workers, farmers, animal breeders, chemical industry workers, carpenters, and workers in the electronic industry. It must be noted that this is a rare disorder and rarely affects the workers. Around five percent of workers have the risk of developing it.In the agriculture industry, farmers are prone to inhale mold and hay as they work in the field for planting and harvesting. Most of the time, the workers are exposed to pesticides, which is the most common cause of pneumonitis. Bird handlers are at the risk of developing this lung infection, as they are surrounded by bird feathers and droppings. Humidifiers at home have a certain kind of mold upon inhaling for a prolonged period of time that can increase the risk of developing extrinsic allergic pneumonia. Hot tubs at home can also increase the risk. Genetics might be a factor that increases the risk of developing this disorder for certain individuals. Exposure to antigens for a long period of time due to a hobby or work is also another risk factor.

Is there a cure/medications for extrinsic allergic pneumonia?

Extrinsic allergic pneumonia or alveolitis is a disorder of the lung due to repeated inhalation of organic dust—animal or vegetable, especially from an occupational setting. These particles are said to be smaller than 5 microns in size and can reach the tiny sacs of our lungs where the oxygen gets exchanged with the blood. Respiratory symptoms and acute fever can set in several hours after exposure to the dust, while the chronic form of alveolitis includes lung tissue degeneration after several years of exposure. The treatment for extrinsic allergic pneumonia relies heavily on the identification of the underlying cause. Exposure to the concerned allergen should be limited and that might help alleviate the mild conditions. If that does not help much, the usage of masks is recommended. However, people with chronic conditions might be advised to switch jobs. Medications in terms of corticosteroid drugs are usually prescribed if the symptoms persist, and in the case of acute scenarios, intravenous steroids might need to be administered. But these medications might not suffice if drastic lung damage has already taken place, and such patients do not respond well to medications. Hence, the earlier the diagnosis is done, the better the chances are of treating extrinsic allergic pneumonia. Although, more and more investigations and clinical trials are underway with the U.S. government funding the studies and some supported by a few private industries too. That gives a ray of hope to those suffering from long-term lung damage as the research has so far exhibited promising results.

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