Eosinophilic pneumonia (EP) is a rare disease characterized by a rapid increase in eosinophils – a type of white blood cell usually produced in response to allergens, inflammation or parasitic infections – in the lungs and bloodstream.
Many conditions, including certain disorders, medications, chemicals, fungi, and parasites, can cause eosinophils to build up in the lungs.
PE can cause a range of symptoms, from fever and shortness of breath to muscle aches and weight loss.
This article discusses the symptoms, causes, diagnosis, and treatment of eosinophilic pneumonia.
Symptoms of eosinophilic pneumonia vary widely, from mild to life-threatening, depending on the type of PE you have and whether it is acute or chronic.
Acute eosinophilic pneumonia usually progresses rapidly, causing:
- Shortness of breath
- Chest pain aggravated by deep breathing
- Tiredness or malaise
- Muscle aches
If left untreated, your oxygen levels can drop and progress to acute respiratory failure within hours or days.
Chronic eosinophilic pneumonia, on the other hand, progresses much more slowly, over days or weeks. If left untreated, it can also have serious consequences, although it is more likely to go away on its own.
What is the difference between acute and chronic?
Acute and chronic forms of the disease differ:
- Acute diseases usually develop suddenly and last for a short time.
- Chronic the conditions develop slowly and may worsen over a long period of time.
Eosinophilic pneumonia can be idiopathic, that is, it can occur for unknown reasons.
That said, it can be triggered by other causes such as:
- Smoking and other inhalation exposures
- Certain medications
Certain occupational factors, such as exposure to inhaled dust, have been shown to trigger eosinophilic pneumonia. Certain medications like minocycline, daptomycin, and the antidepressant venlafaxine have also been linked to eosinophilic pneumonia.
Infectious causes of eosinophilic pneumonia are usually caused by allergens and parasites, including:
- Hookworm. PE can occur after infection with Duodenal ancylostoma or American Necator when the larvae migrate through the lungs.
- Strongyloides stercoralis infection with filariform larvae
- Paragonimus. Also known as lung fluke, Paragonimus infections are usually acquired after ingesting raw or undercooked seafood, especially crabs and crayfish.
- Wuchereria bancrofti, Brugia Malayi, and brugia timori nematode infection. Tropical filarial pulmonary eosinophilia (TFPE) occurs in individuals in tropical regions who acquire nematode infections after being infected by mosquitoes during a blood meal.
- dog roundworm, Toxocara canisor the roundworm cat, Toxocara cati can cause visceral larva migrans, a type of eosinophilic pneumonia
Non-infectious causes of eosinophilic pneumonia include:
- Allergic reactions, such as allergic bronchopulmonary aspergillosis and sensitization to other non-Aspergillus fungi
- Drug exposures (eg, nitrofurantoin, nonsteroidal anti-inflammatory drugs)
- Exposure to toxins (eg, metal particles, inhalant drugs)
- Churg-Strauss syndrome
- Hypereosinophilic syndrome
The first step in diagnosing any lung infection is to take a thorough patient history, ask them to describe their symptoms in detail, and perform a focused physical examination.
If PE is suspected, which is more likely the case if there is a history of parasitic infection or exposure to certain medications, more specialized tests may be ordered by your healthcare provider.
Bronchoalveolar lavage (BAL) is the key test used to diagnose PE. This test takes fluids from the lower part of the respiratory tract to quantify the degree of eosinophilia, check for infection, hemorrhage or malignancy, with the aim of determining the cause or ruling out the presence of disease.
During the BAL procedure, a narrow, flexible tube (called a bronchoscope) is slipped down the trachea into the lungs and a sterile solution is injected into the area in question, removing cells in the process. Aspiration – or the collection of fluid by this method – allows scientists to study cells in detail.
Eosinophils typically make up 0-6% of white blood cells, so higher levels may raise suspicion for PE. In fact, eosinophil levels during acute infection can skyrocket, and the presence of 25% or more eosinophils is an indication of PE.
In addition to the BAL, chest X-rays and CT scans can also be ordered. They may show consolidations that may indicate PE, although these findings are not specific and are often only one piece of the puzzle.
Treating the underlying cause of PE is integral to reducing the progression of your symptoms and preventing serious medical complications.
If you have acute PE, high-dose steroids are usually started immediately, due to the possibility of rapid progression to acute respiratory distress syndrome (ARDS).
In cases of chronic PE, oral prednisone, a steroid, may be prescribed by your healthcare provider.
Significant improvement is often seen within one to two weeks, but can occur as quickly as 48 hours. In rare cases, people may need to take long-term steroids.
Hardly, the symptoms can go away on their own in mild cases of acute or chronic cases, but you need to seek immediate medical attention to avoid serious medical complications.
When PE is recognized and treated early, the prognosis is usually excellent. Complete resolution of your symptoms, including imaging infiltrates, usually occurs within one month of starting treatment.
PE is a rare lung infection, characterized by a massive influx of eosinophils, which can be caused by smoking, environmental exposures, certain medications, and infections.
A word from Verywell
Eosinophilic pneumonia is very rare and resembles other types of pneumonia and the flu. Stopping the offending agent, taking antibacterials or antifungals if needed, and prompt treatment with high-dose corticosteroids usually results in an almost complete resolution of your symptoms and halts the progression of your PE to ARDS.