Exogenous allergic alveolitis is the term used to describe inflammation of the alveoli. It results from inhalation of particulate matter.
What is exogenous allergic alveolitis?
Exogenous allergic alveolitis (EAA) or exogenous allergic alveolitis is inflammation of the aleveoli that is allergic in origin. The alveoli are air sacs in the lungs that are affected by the inhalation of fine dust. This can be chemical substances or organic dust. If the harmful substance is inhaled during an occupation, exogenous allergic alveolitis can be classified as an occupational disease. In Germany, approximately 5 to 15 percent of the population is affected by EAA. The inflammation of the alveoli is most frequently seen in pigeon breeders and farmers.
Causes
The cause of exogenous allergic alveolitis is repeated inhalation of organic dust. If this gets into the lungs, an allergic overreaction occurs in the body. Type III and IV immune reactions are of particular importance. The immune complexes cause the complement system to become active. In addition, messenger substances are formed with inflammatory cells. Cytotoxic T lymphocytes result in the expression of granulomas within the alveolar space. Depending on the extent of allergen exposure and how long it lasts, acute pneumonitis forms in the process. Smaller pneumonitic episodes also pose the risk of developing pulmonary fibrosis. In exogenous allergic alveolitis, the risk of disease varies. An increased risk exists especially in atopics. Responsible for exogenous allergic alveolitis are different antigens that trigger an overreaction of the body. The approximately 300 known antigens include chemicals, animal proteins, bacteria, and fungi and fungal spores. It is not uncommon for EAA to be related to the patient’s occupation. One form of exogenous allergic alveolitis is so-called avian lung. It is caused by bird feathers or bird droppings. Another variant is farmer’s lung, which is caused by mold spores in grain or hay.
Symptoms, complaints, and signs
Exogenous allergic alveolitis can be divided into acute and chronic forms. The acute form sets in about 4 to 12 hours after the patient inhales the trigger. Symptoms include an irritable cough, shortness of breath at rest, headache, chills, and high fever. In addition, sufferers experience a general feeling of illness. Chronic EAA is usually manifested by a gradual decrease in performance, loss of appetite, fatigue and weight loss. During exertion, patients increasingly suffer from breathing difficulties and coughing. The acute form of exogenous allergic alveolitis usually results from a massive intake of antigens. This includes, among other things, cleaning a pigeon loft or moving moldy hay. Symptoms bear resemblance to infectious disease, but are not caused by infection. Often, acute EAA heals on its own after only a few days. The chronic form of EAA is difficult to detect. Over time, it leads to destruction of the lung tissue, also called pulmonary fibrosis.
Diagnosis and progression
With only a single finding, exogenous allergic alveolitis cannot be diagnosed. For this reason, the diagnosis is composed of the exclusion of other diseases. Furthermore, different diagnostic procedures are applied. The symptoms of the disease also play an important role. During the physical examination, the physician often notices a crackling rattle when listening. Sometimes a milky, glassy opacity can also be detected by X-ray examination. However, it does not occur in about one third of all patients. If a chronic form is present, increasing scarring can be detected, but this can also be seen in other lung diseases. Exogenous allergic alveolitis can be reliably detected by high-resolution computed tomography (HR-CT). Even early forms that remain undetected on the X-ray can be diagnosed with its help. By means of a blood test, the detection of special antibodies against the causative agents is possible. It is not uncommon for EAA to be detected late.This can result in delayed treatment of the patient, which in turn creates the risk of pulmonary fibrosis. As a result, fibrosis regresses only slowly or even not at all. However, if timely treatment is given, the course of the disease is usually positive.
Complications
Exogenous allergic alveolitis belongs to a group of immunologically caused lung diseases. Inhalation of various types of organic dust can cause an inflammatory reaction of the lungs, bronchi, and airways. Especially in the field of animal husbandry and in air-conditioned rooms, the symptom tends to be occupational. Sometimes the disease is misinterpreted, because the signs as well as the course of the disease often appear as a flu-like effect. However, a blood count clearly shows leukocytosis, which requires a thorough medical history. After considering the patient’s professional and private background, an exogenous allergic alveolitis can be suspected. If the typical crackling sound cannot be heard when listening to the lungs, imaging procedures and a holistic diagnosis can confirm the findings. If the symptom is prolonged, complications will inevitably arise, which will have an occupational and life-limiting effect on the person affected. In addition to recurrent fevers, a persistent cough, a permanent feeling of flu and exhaustion, exogenous allergic alveolitis can take on chronic proportions. The consequences are shortness of breath, unexplained weight loss, clock glass nails, drumstick fingers, and chronic progressive lung fibrosis. Once fibrosis with scarring of the pulmonary cavities has occurred, it is almost impossible to cure. If the symptom is recognized in time, glucocorticoids are used to allow allergen clearance.
When should you go to the doctor?
This condition should be evaluated by a physician. While it need not lead to immediate complications or to serious symptoms, it can damage the internal organs in the long term. The affected person should see a doctor if he or she suffers from severe shortness of breath or an irritating cough. This can also occur with bloody sputum. If the patient loses consciousness due to the condition, an emergency physician should be called immediately and mouth-to-mouth resuscitation performed. A stable side position can also save the patient. Furthermore, treatment should also be initiated if the affected person suffers from high fever or headache and chills. Furthermore, permanent fatigue or loss of appetite may also be symptoms of the disease. The breathing difficulties and cough usually increase and worsen over time. The initial diagnosis and treatment can be made by a general practitioner or an ENT specialist. The earlier the diagnosis takes place, the higher the probability of a positive course of the disease. However, further treatment will depend on the severity of the symptoms and possibly damage to the internal organs.
Treatment and therapy
To successfully treat exogenous allergic alveolitis, it is essential that the affected person avoid the triggering allergen. Thus, no effective treatment can be given without consistent allergen abstinence. For the therapy, the physician determines whether an occupational disease is possibly present. If the patient avoids the triggering allergen, the symptoms usually disappear after a few days. To successfully combat the inflammatory reaction in acute EAA, the patient receives high doses of glucocorticoids. Some sufferers also have a superinfection, which also requires medical therapy. If the patient suffers from chronic exogenous allergic alveolitis, he or she receives high-potency immunosuppressants. These agents can reduce pulmonary fibrosis. However, if the fibrosis is more advanced, there is a risk of serious complications such as right heart failure or pulmonary hypertension. If the patient’s condition continues to deteriorate, treatment options such as long-term oxygen therapy or lung transplantation may be considered.
Outlook and prognosis
The prognosis of exogenous allergic alveolitis is favorable if certain guidelines are followed. If inhalation of particulate matter is avoided, freedom from symptoms occurs.Although the disease is not curable, the affected person can still achieve relief from the symptoms by regulating his or her behavior. The environment must be cleaned of dust at regular, close-meshed intervals. If the cleaning succeeds in a sufficient measure, no further inconveniences occur. For this purpose, the professional as well as the private premises are to be optimized. In severe cases, exogenous allergic alveolitis takes an unfavorable course. A disturbance of the cardiovascular system may occur. Cardiac activity is so weakened in some patients that serious and life-threatening complications occur. Long-term therapy is necessary to prevent the patient’s premature death. In addition, if exposure to the fine dust continues during inhalation, organ damage can develop. Damage to the lungs can result in permanent respiratory failure and shortness of breath. Artificial respiration secures the life of the affected person. Organ transplantation is indicated in these cases to allow improvement of health. The surgical procedure is associated with numerous risks and side effects. If the donor organ is not accepted by the organism, the patient is at risk of death.
Prevention
The best preventive measure against EAA is considered to be consistent avoidance of the triggering allergen. For example, patients suffering from avian lung should not have contact with ornamental birds and other avian species.
Follow-up
There are usually no special measures or options for aftercare available to the affected person with this disease. In this case, the patient is primarily dependent on a quick and, above all, an early diagnosis. This is the only way to prevent further complications and discomfort. Without treatment of this disease, there is usually a further worsening of the symptoms, so that treatment by a doctor is essential. With this disease, the affected person is primarily dependent on taking medication. It is important to ensure that the correct dosage is taken regularly in order to provide lasting relief from the symptoms. If there are any questions or uncertainties, the affected person should always contact a doctor first. Furthermore, the affected person should not put unnecessary strain on his body and avoid heavy exertion in order not to strain the heart. Help and care from one’s own family or friends are also very important. Psychological care is also very important in order to prevent psychological upsets or depression. Due to this disease, it can also lead to a reduced life expectancy of the affected person.
This is what you can do yourself
Acute exogenous allergic alveolitis usually manifests a few hours after inhalation of the allergen. If the patient avoids the allergenic substances, the symptoms usually disappear on their own after a few days. The best self-help measure is therefore to identify the allergens and avoid contact. This is not always easy. Provided there is no suspicion of the trigger, the affected person should keep an allergy diary. In it, detailed records are kept of what the patient does and which symptoms are observed and when. Such a diary can support the attending physician in performing targeted allergy tests. If the patient has an allergic reaction to a substance that he or she regularly deals with at work, he or she usually has to give up his or her job and look for another occupation. Often, retraining is necessary. Since exogenous allergic alveolitis is often classified as an occupational disease in these cases, patients are relatively well covered. However, those affected should in any case seek advice in good time either from their trade union, from their works council or from a specialist lawyer for social law in order to keep the financial consequences of the disease as low as possible.
